48 Pages of Tips on How to Insulate Doors and How to Repair Doors and Doorways to Seal Air Leaks. You Can Do It Yourself If You Can Be Handy!
Ways to Check for Air Leaks Around Your Doors
How to Seal the Gaps Around Doors and Attic Hatchways
Five Types of Weatherstrip for Doors and How to Mount Them
Door Sweeps and Weatherizing Door Bottoms
How to Insulate Doors By Repairing The Doorways
You can make any door air-tight by trying different types of weather stripping if necessary, and by buying one or two inexpensive hand tools if necessary. Hiring a person to do this work may cost more than you would save in energy bills, and if you do the work yourself, you can re-do it when the materials wear out. Insulating a door may require repairing a door jamb or door stop, because if you add extra insulation to fill large gaps in place of making repairs, the insulation may not last long. Doors that have storm doors should also be insulated because wind will draw heated or cooled air out of the house through small gaps around the storm doors and the primary doors.
This web page shows you how to insulate many types of doors. It also shows how to repair them if they leak because the door frame or the door is rotted or in other ways damaged. I found this information from my experience in weatherizing and repairing doors, and from seeing weatherization that had been done on doors I was repairing, and from reading do-it-yourself websites.
Ways to Check for Air Leaks Around Your Doors
If you are insulating a door you should first check carefully for leaks on a cold winter day or on a very hot summer day. It is easier to find leaks on a windy day.
- To detect very small leaks into or out of the house, move an incense stick along the door’s side, top and bottom edges. If the smoke does not rise straight up, there is a leak. A candle does not produce enough smoke for this test.
- Tape a thin plastic sheet over the door. It will billow inward if air is leaking into the house, or cling to the door if air is leaking out.
- Use a non-contact thermometer. This allows you to measure the temperature around each door to check for cold spots in the heating season and hot spots in the cooling season. It can also be used to check windows and basement walls. They are sold at home centers.
The Chimney Effect
Due to the “chimney effect”, the air pressure is different on each floor in the heating season. The air pressure is lowest in the basement, so air is drawn in more forcefully at gaps around the door. You can normally feel it with your hand on a very cold day. On the first floor it leaks in less forcefully, and if you have a balcony doors on the second floor, you may not feel any air even if there are gaps around the door. You can check for gaps at a second floor doorway using a method to find small leaks, which all work in the heating and cooling seasons. Each can be done from inside the house because they detect airflow in either direction.
When air is heated it becomes lighter and rises like hot air in a chimney. When the air in your house is being heated in winter, it rises to the attic and escapes through the attic vents. This causes the air pressure in the basement to be lower than on the other floors. The air pressure in the attic is greater than the outdoor air pressure, so there, the air flows out of the house. The air pressure at the first floor house, and on the second floor the air pressure will be close to the outside air pressure, so almost no air will flow through in winter, except when the wind blows. Then, air will be drawn out.
How to Seal the Gaps Around Doors and Attic Hatchways
If you find an air leak at the sides or top of a door, pull the door in tightly and test it again. If this stops the leak, you may be able to remount the latch strike plate slightly to make the door close more tightly to seal the gap. It may be hard to find a location where the leak is stopped and you don’t have to slam the door shut. If it is hard to find the correct adjustment you could buy an adjustable strike plate. These are available at locksmith shops, home centers and hardware stores.
To remount a latch strike plate, remove it and fill the holes tightly with pieces of wood shaved from scrap wood. Drill pilot holes and remount the strike plate. If you have a deadbolt lock, check if it still closes easily. If not, file the hole in the deadbolt’s strike plate to make it larger. If you have a lock with vertical slidebolt, you may be able to adjust it by remounting the part that is mounted to the door frame very slightly.
- If the latch strike plate is loose, try using larger screws. If the doorjamb is cracked where the screws enter, put in 2“ screws that will enter the frame behind the doorjamb.
- Insulate doors that have no weatherstrip by mounting a durable type of weatherstrip to the doorjamb. See Five Types of weatherstrip for Doors and How to Mount Them.
- Check that your doorways that have weatherstrip seal the air along the sides and the top. Check for visible gaps between the door and the weatherstrip. A door latch will normally allow the door to move about 1/8” while latched, so check for gaps with the door pushed toward the inside of the house. If the lighting is not good, check if you can slide a credit card between the weatherstrip and the door.
- If the weatherstrip is vinyl or rubber and it has been painted, it has probably lost its flexibility and should be replaced. If the weatherstrip is spring metal (spring bronze) or interlocking metal channels, check if there are drops of paint on it and scrape them off. Where you find gaps, adjust the weatherstrip or replace it with similar, thicker weatherstrip.
If spring metal weatherstrip has a gap because it has small wrinkles or it wasn’t mounted perfectly straight, replace it. Stretch it tightly as you mount it. Make the surface it contacts smooth by sanding or scraping it with a sharp wood chisel. You could leave on the weatherstrip and mount a different type of weatherstrip to the surface the door strikes. Spring metal is more durable but less air-tight than other types of weatherstrip, so you could use them both on different surfaces.
- If felt or self-adhesive foam weatherstrip has a gap, replace it with a more durable type of weatherstrip. See Five Types of weatherstrip for Doors and How to Mount Them.
- If you have aluminum strip with vinyl bulb weatherstrip with a gap and you must adjust it, drill holes through the aluminum strip to remount it. If you don’t, you will put the screws in too close to the old holes and they will fall back into the old holes.
- If you have weatherstrip that fits in a slot in the doorjamb (kerf-fitted) and it is badly worn, replace it. Pull it out and push in a new one. It is made from a strip of soft, flexible foam with a tear-resistant cover. It is available at home centers and can be ordered from the manufacturer of the doorway.
If kerf-fitted weatherstrip has lost its stiffness but is not torn, it can be made stiffer by coating its inside surface with a heavy layer of construction adhesive. If it has contracted in length, leaving a gap at the bottom, you could seal the gap by cutting a small piece of foam pipe insulation and gluing it in.If the door is metal, it may have a kerf-fitted door seal with a magnetic strip in a flexible vinyl case. On some, the door seal is permanently attached to a doorstop, so you must replace the doorstop.
- If there is a gap between a door and the weatherstrip at the bottom corner of the door because the door is warped, there are ways to seal it, which are explained below. Rubber foam weatherstrip tape was not included because it is not durable.
- Mount a weatherstrip doorstop to the doorjamb. This can be nailed on in a slightly curved pattern to fit a warped door. If the doorway has a doorstop, remove it and replace it with the weatherstrip doorstop. If the doorway does not have a doorstop, mounting a weatherstrip doorstop to the doorjamb is too unattractive for a front doorway.
- Check if it is an interior door installed in an exterior doorway. These doors are hollow or have thin floating panels. If so, it should be replaced because it will continue to warp and it is also a security risk.
- Mount bronze spring metal to the bottom of the doorjamb. This is the only durable type of weatherstrip designed to contact the surface edge of a door. If the door becomes more warped the spring metal will still seal the gap.
- Remove the weatherstrip, glue a thin piece of wood to the surface the weatherstrip was attached to, and replace the weatherstrip. To cut the piece of wood, buy a package of 1”x 12” shims. Cut a shim to ½ “ wide using a utility knife. Scrape off the paint and glue on the piece of wood. Nail it with 1” wire brads or 1” wire nails. Replace the weatherstrip.
- If there is a gap under a door that has an insulating door bottoms or an insulating threshold, adjust or replace the weatherstrip or replace its replaceable part. To do this, see Door Sweeps and Weatherizing Door Bottoms. If there is a gap because a wooden threshold is worn down, replace the threshold. See Door Thresholds. If there is a gap because a threshold was mounted too far forward for the door sweep to contact it, replace the door sweep with a multi-fin bottom sweep. Some of the fins will probably contact the threshold. If there is a threshold with a vinyl weather seal and a gap above it, mount a door sweep or an adjustable insulating door bottom to the bottom of the door. If there is a gap because the bottom surface of the door was cut poorly and is not straight. Remove the door and shave the bottom surface.
- If a door has interlocking metal channels with one is mounted to the threshold and the other is mounted to the bottom surface of the door, check them for bent areas and straighten these areas. Bent areas can prevent the door from closing at the bottom.
- If an exterior door has a door sweep and no threshold, mount a threshold. A threshold will prevent the door sweep from dragging on the floor and wearing out soon, and will keep out the rain. If you will not mount a threshold, you could replace the door sweep with a long–lasting aluminum and reinforced rubber door sweep. See Door Thresholds and also, Door Sweeps and Weatherizing Door Bottoms.
- If a door cannot close tightly against the door frame because the door frame is loose at the bottom because it has rotted at the bottom, see Repair Rotted and Damaged Doors and Door Frames.
- If a door is badly warped, it was almost certainly designed to be used as an interior door. You could probably insulate it to seal the gaps, but it will warp further. Also, if you use very thick weatherizing material, the material probably won’t last long. It would be best to replace the door. If the door won’t be replaced, you could remove it, lay it down and flatten it by standing on it and screwing on a 2”x6” board to keep it flat.
- Buy a non-contact infrared thermometer to measure the temperature around each door, checking for cold spots in winter and hot spots in summer. These also allow you to check the walls of the house, for missing insulation. If your utility costs are mainly air conditioning, check for leaks of air conditioned air around the doors by checking from the outside. They are sold at home centers for as low as about $50.
- If your kitchen door has been removed and you use central air conditioning, re-hang the door or replace it with a new door. Closing it will keep some of the kitchen’s heat from entering the other rooms while you cook. It is also a safety feature; a toddler could enter the kitchen when food is cooking on the stovetop and pull off a pot. The door can often be found in the basement, garage or attic.
If it is missing, you could replace it inexpensively with a hollow core door. Hollow core doors cost $20-$30 without hinges or other hardware. A do-it-yourselfer can hang a door using a home improvement manual, video, or website. Spring-loaded hinges could be installed to keep the door closed. After installing the door, weatherstrip it and mount an inexpensive interior threshold. Mount a multi-fin door bottom. These are more attractive than door sweeps. See Door Thresholds and Weatherizing Door Bottoms.
- Insulate the door between your house and the garage. Do this even if your garage is heated because the garage door may occasionally be left open. Mount weatherstrip to the sides and top, and mount a door bottom weatherseal.
- Seal the gaps around the doors to your attic and basement. In the heating season, the air that leaks through these doorways flows up to the attic, where it leaves the house through attic vents. This insulation should be attractive, so use white EDPM cellular rubber weatherstrip tape. See EDPM cellular rubber weatherstrip tape. Mount a multi-fin door bottom at each door if the gap is not too wide or too narrow, because these are more attractive than door sweeps. Mount a ½” thick oak interior threshold at the attic doorway, but if the door opens over a thick carpet, mount a threshold that is thicker than ½”. Do not mount a threshold at the doorway to the basement because a person could trip on it and fall down the stairs.
If you won’t mount a threshold to the door to the attic, you could block the air with a “Double Draft Stop”. You slide this under the door. These are made of cloth, with two solid foam tubes, one for the inside and one for outside of the door. It is sold at hardware stores and home centers. You could post small signs at both doors, “PLEASE CLOSE THIS DOOR IN WINTER”.
- If your furnace or boiler is in a room with an exterior door and a louvered air vent on the wall that has been sealed, the furnace is being supplied by fresh air by that leaks in under the door. Do not weatherstrip the exterior door unless you also open the air vent on the wall.
- If you have an exterior door that you must slam to close, repair it because some members of your household may not always close it, allowing air to enter.
- First, check if the hinge screws are loose. If they loose, try to tighten them. If you cannot make them tight because they spin instead of grabbing the wood, replace them with 2½” screws. These will fasten the hinge to the wall stud behind the jamb. You may have to drive some of them in at slight angles to enter the stud.
- If there is brick or block behind the doorjamb and some of the holes are stripped, move those screws to different locations on the hinges by drilling holes into the hinges.
- Check if the door doesn’t close easily because there is too much paint on the hinge edge of the door or on the doorjamb it contacts and scrape it off.
- If the door doesn’t close well because an edge on the lock side rubs against the doorjamb, use a plane, a rasp (wood file), belt sander, or wood shaver to remove wood from the door.
- As a last resort, you could remount the strike plate, but then the door would probably not contact the weatherstrip along all its sides. To remount the strike plate, remove it and fill the screw holes with wood by cutting slivers of wood and hammering them into the holes. Drill pilot holes to remount the strike plate.
- Insulate the doorway to any room that is often warmer or cooler than the rest of the house, such as a room with a space heater or window air conditioner. This may be a room that you don’t often use, so you have closed the register or turned off the radiator. It may be a “sun room”, a room with a wall of windows, which is colder in the winter and hotter in the summer. This insulation should be attractive, so use white EDPM cellular rubber weatherstrip tape. Mount a ½” oak interior threshold and a multi-fin door bottom. The threshold will have to be thicker than ½ if the door opens over a thick carpet. If you won’t mount a threshold and door bottom, you could block the air with a “Double Draft Stop”, which you slide under the door (see picture above).
- Install a storm door at your front doorway, but only if it would beautify your home in addition to saving energy. If your primary door is old and unattractive and you install an attractive storm door, it will beautify your home and increase its property value, but the energy savings alone would not justify its cost. Most modern storm doors cost from $150 to $350, plus installation. You can install one yourself if you are an experienced do-it-yourselfer. You first mount a metal frame to your doorway.
The energy savings you would receive from a storm door depends on how well your primary door insulates. If, for example your front door is steel and not filled with insulation, it insulates poorly. You can tell if a steel door is filled with insulation by touching it on a cold day.
Some storm doors have a full view glass panel that you replace with a screen panel during warm weather. These storm doors can be locked, allowing you to leave open the primary door with the glass panel installed, to let in sunlight and lower your lighting costs. A “ventilating storm door” has two glass panels and one screen panel, which you slide up and down, similar to triple track storm windows. “Self-storing storm doors” or “retractable screen storm doors” have an upper glass panel can be dropped down and a retractable screen is pulled out from where it is hidden in the frame, rolled up like a window shade.
Steel storm doors are more durable than aluminum storm doors, and may be available in the same price range. Storm doors made of materials other than steel or aluminum are the least durable. Glass panes are better than vinyl panes because vinyl panes may warp, allowing air gaps, and vinyl panes become less clear over time.
- If a door closer on a storm door is not working, replace it. If you buy a similar model you can connect it to the old the brackets instead of replacing them.
- If you have a storm door with a door closer, check that it latches when the door closer pulls it shut. Test it with the primary door closed because the air pressure will be higher, which could cause it to not close. If a storm door does not latch, adjust the door closer to make it close slightly more forcefully by turning its adjustment screw. This is at the end of the cylinder, on the end opposite from the door hinges.
If it still does not latch, check if its four hinges, or one hinge that is the length of the door (“piano hinge”) is loose. If it has four hinges and the hinge screws are loose, replace them with larger screws because if you only tighten them, they will come loose again. They probably screw into aluminum, which is easily damaged. Either use screws that are slightly larger in diameter or use 2” screws that will go through the metal frame into the wood behind it. To put in screws that are slightly larger than the screws you removed, use wood screws and a cordless drill. Aluminum is softer than steel, and the drill will cut new threads as the screws go in.
If the storm door has a piano hinge in place of four hinges, check if the screws that attach the piano hinge to the storm door’s frame are loose. It will have many screws, so it may be enough to tighten them instead of replacing them with larger screws. Otherwise, you could replace a few of them with 2” screws and screw the piano hinge directly into the wood behind the frame. If there is a large gap between the door and the frame on the hinge side, the hinge or hinges are bent. Drill holes in the hinges close to the hinge pins and screw on the hinges through these holes.
- If you have a storm door, check that it contacts the weatherstrip when it is closed. If there are gaps, the storm door’s frame was not mounted to the doorjamb correctly. Insert shims between the storm door’s frame and the doorjamb where necessary to close the gaps. If this creates gaps between the frame and the doorjamb, caulk the gaps.
- If a storm door contacts the weatherstrip at the top but not the bottom, install a second door closer at the bottom. Many storm doors have two door closers to prevent infiltration.
- If you have a storm door that closes hard but does not latch, adjust the strike plate, they are adjustable. If it still won’t latch, file out the hole in the strike plate to make it larger.
- If you have a storm door, check if its door sweep or insulated door bottom contacts the surface below it and lower it if it doesn’t. These are both adjustable. If there is no step and the door sweep or insulated door bottom drags along the ground, raise it to 1/16” above the ground to prevent it from tearing.
- Maintain your storm door to prevent problems: adjust the strike plate to have a margin of safety and lubricate the hinges.
- Check if any of the fins on the bottom of the storm door are torn. Replacement fins are available in the weatherization department of some home centers and hardware stores. If a vinyl fin is not available, mount a single-fin or dual-fin storm door bottom. These are narrower than other weather seal door bottoms. If one is not available, mount a conventional door sweep. This may be acceptable for a rear door but too unattractive for your front door. A replacement fin for your brand of storm door can be ordered at a retail store that carries that brand.
Modern storm doors have thin brush-like strips called “pile weatherstrip” along the sides and top. If your storm door has this, check if any is missing or worn. A typical home center will carry one size of “storm door pile weatherstrip”, but other sizes can be ordered. A store that carries your brand of storm door can order it or may have it in stock.
- If you have a storm door with a removable glass or vinyl panel, check if air leaks in around the edges of the panel. If so, tighten the panel’s mounting clips.
- If you have an inner and an outer front door and members of your household leave the inner door open, mount a door closer on it to keep it closed.
- If you have a mail slot in the front door and its cover doesn’t always close, lubricate it, repair it, or replace it. If it is many years old, the opening in the door will be smaller than those of current doors, so you won’t be able to buy a mail slot cover in a store. You will have to order one, or cut the hole in your door to the size of a larger mail slot cover. This would be a better choice because envelopes are larger than in years past. You would probably need to use a reciprocating saw to make the cut.
- If your climate is cold and you have a mail slot in your front door, replace its cover with an air-tight cover. These are called “magnetic mail slot covers” or “energy-efficient mail slot covers”. They are more available in stores in colder climates.
- If the entrance to your attic is a hatch, insulate it. A hatch entrance normally has a thin board as a door, without hinges. In the heating season, warm air rises forcefully into the attic through gaps around the hatch door and leaves the house through the attic vents. This is due to the “chimney effect”, in which heated air rises like the smoke in a chimney. In the cooling season, since the attic is often over 100°, the hot air in the attic escapes through the attic vents, forcefully drawing air conditioned air into the attic through gaps in the attic floor and at the hatch. If the door is not warped, mount EPDM weatherstrip to the wood the door rests on. See EDPM Cellular Rubber Weatherstrip Tape
If the door is warped, flatten it by screwing boards onto the top of it.
- Cut pieces from a 1”x10” board to cover the hatch door.
- Mount them to the top of the door using 1¼” drywall screws, putting the screws through the door into the boards. Use many screws to prevent the door from warping perpendicular to the boards.
- Cover the screws with joint compound, using a 4” or 6” taping knife. Sand it when dry, and paint the door.
- If the hatch door is warped and you will not straighten it, weatherstrip it with rubber foam weatherstrip tape. This compresses more than other weatherstrip materials. It is available in thicknesses of up to 7/16”. Only “low density” rubber foam weatherstrip tape is very compressible. It may have to be replaced in a few years. Prepare the surfaces it will stick to by sanding or scraping them. After sticking it on, staple its ends or nail them with 3/4 “wire nails.
- If you have a hatch and your attic floor is insulated, mount a piece of insulation to the top of the hatch door. If you have a scrap piece of fiberglass batt insulation, cut a piece from this to use. If you don’t, buy a 16” wide roll of multi-purpose fiberglass insulation, for about $7. It is only R-3, so nail on two or three layers to match the insulation on your attic floor.
- If you have a crawl space below the first floor and its entrance is a hatch in the floor above, seal the gaps around the hatch with EPDM weatherstrip. This is much more durable than self-adhesive rubber foam weather seal. Mount the weatherstrip to the surfaces the hatch door will rest on, after scraping or sanding them.
- If the entrance to your attic is a hatch with pull-down stairs and the door doesn’t close tightly, try to repair the stairs or closing mechanism before sealing the gaps with weatherstrip. You can often repair it by tightening the bolts. If it was poorly installed you may need to remount the closing mechanism or hinges. Repairing it is better than sealing large gaps with thick weatherstrip because this is not durable.
- If the entrance to your attic is a hatch with pull-down stairs and the door closes tightly, mount weatherstrip if there is none. Use EDPM cellular rubber weatherstrip tape. Carefully prepare the surfaces that you will stick it to by scraping or sanding them. After mounting the weatherstrip, staple down its ends with 5/16” or ¼” staples.
If there are gaps which are too wide for the weatherstrip, glue 1/2“ wide strips of wood to the surfaces of the door that the weatherstrip will contact. The strips could be cut from paint stirring sticks, using a utility knife. After gluing them into place, nail in 1” brads or 1” wire nails to hold them until the glue dries. Instead of using strips of wood, you could use rubber foam weatherstrip tape. This compresses more than other weatherstrip materials. It is available in thicknesses of up to 7/16”. Only “low density” rubber foam weatherstrip tape is very compressible. It may have to be replaced in a few years.
- If the entrance to your attic is a hatch with pull-down stairs and the door closes tightly and there is weatherstrip, check if it is sealing tightly. You can’t see the weatherstrip when the hatch is closed, so it is hard to check for a gap. One way is to paint the frame where the weatherstrip will contact it, and then close and open the door. Where ever the weatherstrip does not get paint on it, there is a gap. You can wash off the paint before it dries. Another way is to close the door with a sheet of paper between the frame and the weatherstrip in many locations around the frame. Where ever you can slide out the paper without effort there is a gap.
Replace the weatherstrip if there are gaps. Use EDPM cellular rubber weatherstrip tape. Carefully prepare the surfaces it will stick to by scraping or sanding them. After mounting the weatherstrip, staple down its ends with 5/16” or ¼” staples. If gaps are too wide for this weatherstrip, glue 1/2 “wide strips of wood to the surfaces of the door that the weatherstrip will contact. The strips could be cut from paint stirring sticks, using a utility knife. After gluing them into place, nail in 1” brads or 1” wire nails to hold them until the glue dries.
- If you have French doors or another style of double doors, check if air leaks through between the doors. One door is held in place by slide bolts at the top and bottom. This door will normally have a strip of molding attached, which is a doorstop for the other door. Weatherstrip will be mounted to this molding. The doors must be aligned at the top and bottom for the gap to be closed. If there is a gap, check if one of the slide bolts is not closed. If one is not closed, check if it is hard to slide into its hole. If so, this may be why it wasn’t closed. Make it easier to put in by making the hole very slightly larger.
A gap between the doors could be caused by the latch not pulling the doors tightly together. You can correct this by slightly relocating the strike plate in this way: Remove the strike plate; then fill the two holes it leaves with slivers of wood; then drill pilot holes for the screws and remount the strike plate.
If the gap between the doors is only at the top or bottom because one of the doors is warped, you could replace the weatherstrip with pieces that allow for a larger gap at the top or at the bottom. First, remove the weatherstrip and scrape the surface to prepare it for self adhesive weatherstrip; then, mount rubber foam weatherstrip tape of two different thicknesses, the thickest where the door is warped. The thickest available will probably be 7/16”, and it will compress to about 1/8”. The thinnest available will probably be ¼”, and will compress to about 1/16”. Buy only low-density tape because high density tape is not very compressible.
- If a door is warped too badly to mount rubber foam weatherstrip tape, glue ½” wide strips of wood to the surface the weatherstrip tape will contact and mount the tape to it:
- Using a knife, cut the strips from wooden shims, which taper down from about ¼” to about 1/16”, or cut strips from paint stirring sticks.
- Prepare the surface that the strips will stick to by scraping off the paint with a wood chisel.
- After gluing the strips into place, put in 3/4” brads or wire nails to hold them until the glue dries. If available, use large tongue-and-groove pliers to squeeze the brads or nails into place in place of nailing them in.
- Stain or paint the strips of wood to match the door before attaching the weatherstrip.
- If a wooden door has a badly damaged edge that allows air to enter, repair it. Marine epoxy should be used for this because it is the most durable wood filler. Drill many short holes into the door where the epoxy will be applied to create a strong bond. Apply the epoxy, carefully following the directions provided.
- If you have a pet door that was not designed to be airtight, replace it with an airtight model. These are available at pet stores and some home centers.
- If your climate is very cold and you have a pet door, fill the hole in the door with a piece of fiberglass insulation on cold nights. This is available in small rolls, 16” wide, as “pipe wrap insulation” for about $6.
- If you have sliding patio doors, inspect their weatherstrip. Modern patio doors have either pile or thin vinyl strip weatherstrip along all four edges of each door, either on the door or on the frame. Check if it is badly worn. Pile is available at home centers, but often in only one size. It is available in many sizes in window repair stores and can be ordered online from a pile weatherstrip manufacturer or from the patio door manufacturer. Vinyl weatherstrip can be ordered from the manufacturer.
- If you have sliding patio doors, check that their side edges contact the doorjambs from top to bottom. If not, adjust the two wheels at the top of each door. If they were not designed to have weatherstrip, mount weatherstrip around them. Mount thin weatherstrip to the doorjambs to compress very flat when the doors are closed so the latch closes easily.
EPDM ribbed-profile weatherstrip would be best because it is durable, but some doors will not close with it. It is 1/8” thick and compresses to about 1/16” thick. If this is too thick or not available, use ¼” thick rubber foam weatherstrip tape. Those brands labeled as “low-density” can be compressed to be paper-thin. See Rubber Foam Weatherstrip Tape. For either type, prepare the aluminum surface it will stick to by sanding it.
If your climate is very cold, you could mount aluminum strip with vinyl bulb weatherstrip to the frame members above and below the patio doors, but it is unattractive. This would be screwed onto the frame, so it should last for many years. Mount it with self-tapping sheet metal screws. See Five Types of Weatherstrip for Doors and How to Mount Them.
- If you have sliding patio doors, seal the gap under the doors. The doors hang from a track and the gap beneath them should not be filled with weatherstrip. One way to prevent air from flowing under the doors is to lay a small carpet next to the doors in winter, with its edge rolled up against the doors. Another way is to make a “door draft snake”, and lay it on the floor at the bottom of the doors. Cut out a long rectangle of cloth, roll it into a cylinder and sew the edges together. Stuff in rags or polyester fiberfill. Another way is to cut a strip from an old, heavy rug to lie over the gap.
- If you have a sliding patio door that you sometimes leave unlatched because it is hard to latch, repair it if latching it closes a gap between the doors. If it has a “keeper”, which the latch hooks into, adjust this. If instead it has a strike plate, you may need to file the hole in this to make it larger.
- If your climate is very cold and you have sliding patio doors that you don’t use often, cover them in winter with 12” wide strips of “foil and fiberglass duct insulation”. Hang curtains to cover the panels if you don’t have them. Thermal curtains or drapes would further improve the insulation. Foil and fiberglass duct insulation is available in plumbing stores and in the HVAC department of home centers. Most types of rigid insulation cannot be used because they emit toxic gas in a fire if not covered by drywall. Foil and fiberglass duct insulation is thin, but the foil increases its R-value by reflecting thermal radiation. See the topic of home energy conservation, Curtains, Drapery, Blinds, Shutters and Awnings.
- If you have sliding patio doors that will not be used all winter, “Shrink film” may also be used to insulate them. This is very transparent plastic film which you tape to the wooden frame around the doorway. It is effective because it is airtight and it creates a dead air space that insulates well, but you cannot open the patio doors. You tape it on with double-sided tape then heat it with a hair dryer to make it tight and transparent. It may be called, “Patio Door Insulation Kit”. It can only be used several times, so it may not lower your heating costs by as much as it costs, but it will make the room warmer while letting in light.
- If you have a door with window panels and no storm door, in a location where its appearance is not important, cover the window area with rigid plastic. This insulates well because the space between the plastic sheet and the glass is “dead air insulation”. Also, if you use an unbreakable plastic material and you mount it very strongly, it could make the door more secure against break-ins. The unbreakable plastics available in home centers and hardware stores are polycarbonates, such as LexanTRADEMARK.
Cut the sheet to size using a circular saw. The cut will be neater if you use a panel blade. Apply a bead of clear caulk to the door. Mount the sheet by putting in screws around the edges, with large washers that overlap and clamp on the sheet. Do not drill holes in the plastic unless it will extend 5” beyond the glass and you drill the holes close to the glass, because holes close to an edge may cause the plastic to crack.
- If your air conditioning costs are high, you could cover your patio door glass with insulating window film. It is most effective if the patio doors allow direct sunlight into your home. Buy a window film that is described as “insulating”. The most effective type for lowering air conditioning use is “mirror reflective film”, also called, “mirror silver privacy film”. This appears as a mirror from outside of the home and prevents persons from looking in.
Insulating window film has several names, such as “heat-control window film” and “heat-blocking window film”. Avoid buying window film that is designed to prevent persons from looking in, not to block out heat, such as stained glass pattern window film, “frosted white privacy window film” and other decorative window films. A product may appear to be insulating window film if it is described by phrases such as, “blocks up to 99% of UV rays to help reduce fading”, but these are not designed to block the heat because heat energy is transmitted more through infrared radiation than through UV radiation. These are designed mainly to prevent your furniture from fading. Buy a brand of film that has an installation video on the company’s website.
- If an exterior doorway has an interior door in it, replace the door with an exterior door or cover it with insulation. Any wooden door that is hollow or has thin panels is an interior door. The heat loss through an interior door due to conduction is higher; the door is not secure against break-ins; and it will warp, allowing air to enter.
If you will replace it, a flat, solid core door is not expensive. To hang it you must make notches for the hinges and drill holes for the lockset. An experienced do-it-yourselfer can do this with the help of a do-it-yourself video.
If you choose to cover it with insulation instead of replacing it, you could staple on 12” wide strips of “foil and fiberglass duct insulation” or 16” wide fiberglass “pipe wrap insulation”. These are both available in plumbing stores and in the HVAC department of home centers. The foil side of foil and fiberglass duct insulation should face the inside of your house to reflect heat radiation. Foil and fiberglass duct insulation is thin, but the foil increases its R-value. Most types of rigid insulation cannot be used because they emit toxic gas in a fire if not covered by drywall.
- If you have jalousie doors or jalousie storm doors, seal the gaps between the glass slats. Jalousie doors and storm doors have glass slats that open with a crank. In regions of the country where these doors are common, some stores sell “jalousie jackets”. These are clear, vinyl sleeves that fit over the edges of the louvers to make them airtight when closed. You could, instead, apply “removable insulation”. This peels off in one piece without leaving stains. It is sold in the paint departments of home centers and hardware stores.
- If you have a pocket door (an interior door that slides into the wall) that does not close and you could close it to lower your energy costs, repair it. Remove the piece of casing at the top of the doorway and check what needs to be repaired. One of the wheels may have fallen off of the track.
- If the edge of a door in the area of the door latch is badly damaged, allowing a sizable gap, install a “backset lock and door reinforcer”. This is made of brass sheet metal. It wraps around the door, enclosing the area near the latch and doorknob. It is designed to strengthen the door against break-ins. They are available in brass- and silver-colored finishes at home centers and locksmith shops. To buy a door reinforcer, measure the door’s thickness and the “backset” of the doorknob (2 3/8″ or 2 3/4″).
- If you have an insulating threshold with a vinyl insert and you must push the door forcefully against it to close, the vinyl insert will need to be replaced too often. Take down the door and bevel the bottom of the door with a belt sander or plane.
- If a door or doorjamb is rotted, damaged or badly warped, allowing gaps at a corner or edge, repair it. Very thick foam rubber tape would seal the gap in many cases but would not be durable. To repair a door or doorjamb, see How to Insulate Doors by Repairing the Doorways
- If you have a solid wood exterior door with “floating panels” that has cracks in the panels that let air through, repair the panels. The door will look much better with the panels repaired than caulked. The panels were designed to expand and contract within the grooves in the door with changing temperature and humidity. They crack because they contracted when the weather was cold or dry, and their edges were sealed in place by paint.
Fill the crack with construction adhesive, and slide one side toward the other to close the gap. If necessary, drill a tiny hole in the panel you will slide, stick in a finishing nail, and pull the nail with pliers to slide the panel.
- If a door is too short and at a location where its appearance is unimportant, seal the gap at the bottom with “vinyl garage door top and side seal”. This is a 1¾” wide vinyl strip, sold in home centers with weatherization products.
- If you have bulkhead doors at the entryway to your basement, seal the gaps around the basement door at the bottom of the stairs beneath the bulkhead doors. Bulkhead doors are steel doors designed to keep rain from entering the stairwell and to secure the house. They are mounted at the top of stairs that lead to a basement door. They are drafty and cannot be insulated.
- If you have an exterior door with a cracked pane of glass and air is leaking through the crack, replace the glass. On most doors with glass panes, the panes are held in by strips of wood rather than glazing putty. If it is held in by strips if wood:
- Lay a drop cloth at both sides of the door to catch small pieces of glass.
- Use a utility knife to cut the paint around the strips of wood.
- Using a hammer and a stiff 1” putty knife, pry off the strips of wood. This should be done before you buy the glass so you can measure the dimensions accurately. Save the wire brads to re-use.
- Buy the pane of glass. You will need a nail set or a square head nail (masonry nail) to nail in the wire brad. If you don’t have either, buy a nail set.
- Put in the pane. Carefully nail in the strips of wood. To avoid breaking the glass, try to push in some of the brads by squeezing them into the wood with large slip-joint pliers.
- Caulk around the strips of wood, and when the caulking is dry, paint the caulk.
Five Types of Weatherstrip for Doors and How to Insulate Doors With Each of Them
To choose a type and thickness of weatherstrip usually requires trial-and-error. In fact, the weatherstrip that works best for the top of the door is often too thin for the bottom of the door because the gap is slightly wider there. The key to weatherstrip a door is to buy a variety of weatherstrip and try several if necessary.
After mounting the weatherstrip, check that the deadbolt lock closes easily if the door has one. If the key is hard to turn, it may break.
Type 1 – EPDM Cellular Rubber Weatherstrip Tape
EPDM cellular rubber weatherstrip tape is self-adhesive weatherstrip tape made from EPDM cellular rubber. EPDM is a type of rubber designed to keep its shape for many years, even in sub-freezing conditions. It is cellular because it has air cells for compressibility. It is normally the best type to use where the weatherstrip must be attractive.
If it is the same color as the doorway, it is almost unnoticeable when the door is open. It is available in white and brown, and in various shapes (profiles), each designed for a different gap thickness. Most of the profiles are hollow, designed to collapse to fill a greater range of gap thicknesses. It will stay in place for many years if it is mounted to a clean and dry surface, and longer if it is stapled or nailed at each end.
Medium size EPDM weatherstrip has a “D-profile” and fills gaps from 1/8” to ¼”; the thin size has a “ribbed-profile” and fills gaps from 1/16” to 1/8”; and the large size has a D-profile and fills gaps up to 5/16” thick. Brown EPDM is available in some stores, but normally only in one thickness. On most doors, the gap varies too greatly to seal it with only one thickness of EPDM, so it is better to use white EPDM.
How to Mount EPDM Cellular Rubber Weatherstrip Tape to a Doorjamb
Tools and Materials:
- 3/8” wide EPDM weatherstrip of the sizes that will fit the gaps (trial-and-error is usually
- necessary so buy at least two sizes)
- sharp wood chisel or sandpaper
- 3/4” wire nails or staple gun and 5/16” staples
- hair dryer (only if air temperature is below 50° or if there is morning dew)
- shims and construction adhesive (only if the weatherstrip will be mounted to shims where the gap is wide)
- utility knife
- staple gun and 5/16” staples, or ¾” wire nails
Mount the weatherstrip:
- Do not mount the weatherstrip if the outdoor temperature is below 40º or it has rained recently, as the instructions indicate.
- On the latch side of the doorway, mount the weatherstrip to the surface that the door strikes.
- Sand the surfaces the weatherstrip will stick to, and wipe off the dust. This will clean it without getting it wet, and will rough it up for better adhesion. If the surfaces have bumps from dried paint, scrape them off with a wood chisel.
- If the outdoor air temperature is below 50° , dry the frame with a hair dryer. The door frame will be very slightly damp from warm, inside air leaking out around the door and condensing on a cooler door frame.
- If the gap is greater than ¼” at the bottom of the door (normally because the door is warped), build up the area with a shim before putting on the weatherstrip. Use a shim from a package of shims and cut a strip 3/8 “ wide with a utility knife. Scrape the paint off of the frame and glue on the shim with construction adhesive. Nail in two ¾” wire nails. To build up an area where the gap is long, cut a 3/8” strip from a paint stirring stick and carve it to make it tapered, similar to a shim.
- If the gap is too narrow somewhere for D-profile weatherstrip, and if ribbed profile weatherstrip, which is thinner, is not available, cut D-profile weatherstrip to make it thinner. Using scissors, cut off the curved part to make it about 1/6” thick.
- If your door swings inward, stand outside and close the door. Push it inward and measure the gap at its widest and narrowest points.
- Check that the latch closes easily. If you must slam it to close it, replace the weatherstrip with thinner weatherstrip in the area where the gap was thinnest.
- Mount weatherstrip along the top of the doorway and check that the latch still closes easily.
- On the hinge side of the doorway, mount the weatherstrip differently. Mount it to the doorjamb, so that the edge surface of the door compresses it.
- Staple the ends of each piece of weatherstrip with 5/16” staples, or nail in ¾” wire nails.
- If the door has a deadbolt or lock with a vertical slide bolt, check that it still locks and unlocks easily. If you have a deadbolt that has become hard to close, file off about 1/16” from the hole in the strike plate. If you have a lock with a vertical slide bolt and it has become hard to close, it may be better to change the weatherstrip rather than to adjust the lock. The piece mounted to the door frame would need to be moved very slightly and this is usually difficult. Only the weatherstrip on the lock side of the doorway (not on the top or hinge sides) would need to be replaced with thinner weatherstrip, and probably only in one spot where it is tightly compressed.
Type 2 – Weatherstrip Doorstops
Weatherstrip doorstops have a strip of weatherstrip inserted in them. They are relatively durable and are attractive if used to replace an existing doorstop. They are not attractive when mounted on a doorjamb that has no separate strip of wood as a doorstop. Most exterior doorways do not have a separate doorstop, as all interior doorways do. If a door is warped, you can seal the gap by mounting a weatherstrip doorstop to fit the curvature of the door. They are available in the door section or the weatherization section of home centers and hardware stores.
How to Mount a Weatherstrip Doorstop
- If there is a doorstop, remove it. First, cut the paint along both sides with a utility knife and pry the doorstop off with a stiff putty knife.
- Measure the door frame and cut the pieces of weatherstrip. The left and right sides of the frame may be different. A hacksaw or small wood saw will cut the wood neatly and a knife is best to cut the weather seal.
- Paint the pieces with exterior paint. Paint the end surfaces thoroughly for protection from rot.
Nail the doorstop to the latch side of the doorway using 2″ galvanized finish nails. Push the door inward as far as it will go before nailing; most doors move about 1/8″ when latched. Hammer each nail only half-way in so it can be removed if you move the doorstop. Nail in a few nails and check if the door still latches easily. This won’t be necessary when nailing doorstops to the top and hinge sides of the doorway. If the door has a lock with a vertical slide bolt, also check that this operates well after nailing in each few nails. This type of lock is hard to remount if it doesn’t operate well after the doorstop is nailed on. If there is a deadbolt lock, you can make it work well by filing the hole in the striker plate to make it larger.
- Hammer the nails in below the surface using a nail set or square cut nail and cover the holes with exterior caulk.
- Caulk where the doorstop meets the doorjamb.
- If the door has a deadbolt, check that it still locks easily. If not, file out about 1/16” from the hole in the strike plate.
- Nail strips of doorstop to the hinge side and the top of the doorway. It may not be necessary to hammer the nails only half-way in and close the door to check it after every few nails because the door compresses the weatherstrip more forcefully on these surfaces.
Type 3 – Aluminum Strip with Vinyl Bulb Weatherstrip
This type of weatherstrip has no standard name, its manufacturers have different names for it, such as “doorjamb weatherstrip”. It is made of a rigid strip of aluminum and a vinyl bulb. The rigid strip is screwed to the doorstop or to the doorjamb if there is no doorstop, at a position where the vinyl bulb is compressed by the door when it closes. It is unattractive, but probably suitable for rear entrances and basement doors. It is popular because it is more durable than any type of self-adhesive weatherstrip.
How to Mount Aluminum Strip with Vinyl Bulb Weatherstrip
Tools and Materials:
- Tape measure
- Cordless drill
- 3/32” and 1/8” drill bits
- Package of aluminum strip with vinyl bulb weatherstrip, with mounting screws. If the package has nails, buy screws to use instead. A package has three pieces to do one doorway.
Mount the Weatherstrip
- Measure the sides and top of the doorway and cut pieces of weatherstrip. The left and right sides may be different.
- Use a hacksaw to cut the aluminum, and a knife or scissors to cut the vinyl.If your door swings inward, stand outside and close the door. Push the door away from you to make the gap as large as it could be.
Mount a piece of weatherstrip to the latch side of the doorway. A door may move about 1/8” while latched, so the weatherstrip should be mounted to barely contact the door when the door is farthest from the weatherstrip, so that the bulb is compresses about 1/8” when the door is closest to the weatherstrip. Do not put the screws in tightly because the final turn can move the weatherstrip slightly. After each screw is put in, check that the door latches and there is no gap. If you have a lock with a vertical slide bolt, check if this still locks easily after putting in each screw. These are hard to adjust if they don’t lock easily. If the door will not latch and a screw must be moved, drill a new hole for it in the aluminum strip, using the 1/8” bit. It is easy to drill through the strip if the bit is sharp. If you don’t do this you will drive the screw into the wood too close to the previous hole and it may move into it.
- After mounting the first piece of weatherstrip, check that a credit card cannot slide behind it when the door is pushed inward.
- Mount weatherstrip to the top and hinge sides of the doorway. In these locations the door is more “forgiving”, you probably don’t need to check if the door closes after putting in each screw. Check that the door latches and test the lock with vertical slide bolt if you have one.
- If the door has a deadbolt,check that it locks and unlocks easily. If not, file about 1/16” from the hole in the strike plate.
Type 4 – Spring Bronze Weatherstrip
Spring bronze weatherstrip, or spring metal weatherstrip, can last very long if it is mounted well because it is nailed on and because it is made from bronze. Its disadvantages are that it is not perfectly air-tight and it cannot be effectively mounted at the lock area unless you mount a “spring bronze lock strip”, which most stores don’t carry. It should be used together with a self-adhesive weatherstrip mounted to the doorstop. Spring bronze weatherstrip is mounted to the jamb, where it contacts the edge surface of the door, and the self-adhesive weatherstrip mounted to doorstop is compressed tightly when the door is close. With self-adhesive weatherstrip mounted to doorstop, it is not important that you mount spring bronze weatherstrip at the lock area.
Spring bronze weatherstrip may be used only at the bottom of the door jamb if the door is warped and doesn’t contact the self-adhesive weatherstrip there. A “spring bronze lock strip” is a thin piece of spring bronze designed to fit behind the lock. Spring bronze is mainly available in large rolls. Some builders’ supplies offer a kit designed to weatherstrip one door with spring bronze weatherstrip, which includes a spring bronze lock strip.
Spring bronze can seal fairly well if perfectly installed if the gap is close to 1/8”, but not if the gap is close to ¼”. If the gap is less than about 1/8”, you must plane the door to make space for it. It seals just as well on warped doors as on flat doors, but self-adhesive weatherstrip mounted to the doorstop does not. The nails can be easily driven in with a brad driver. You insert a nail in its barrel and punch in the nail. Brad drivers are available in some hardware stores and builders supplies.
Tools and Materials:
- Roll or package of spring bronze weatherstrip. Both have brass nails included
- Brad driver
- Nail set or square cut nail (if no brad driver is used)
- Metal shears
- Sharp wood chisel to scrape the surface
- Belt sander or plane to remove wood from the door if the gap is less than 1/8”
Mount the Weatherstrip:
- Check that the gap is about the same from top to bottom. If not, hinge screws may be loose. Tighten any loose screws. If any are loose and cannot be tightened because the wood is damaged, replace them with 2½” screws, which will mount the hinge to the stud. You may have to drive in the drywall screws at a slight angle to enter a stud. Use 2½” drywall screws or similar long screws with a small head.
- Check that the gap between the door edge and the doorjamb is between about 1/8” and ¼” all along the latch side and the top side. It may only need to be 1/16” wide on the hinge side because the door forcefully compresses the weatherstrip there. Where the gap is less than about 1/8”, sand or plane the door to create an 1/8” gap. If the temperature is very cold when you measure the gap, and it is only about 1/8”, it will be less than 1/8” when it becomes warm and humid and the door expands. Then, the door will be hard or impossible to close, so make the gap larger. To sand or plane it, remove the hinge pins, take off the door and set it up on its edge. If you sand or plane it while it is hanging, the new edge will not be straight.
- Scrape off any paint drops on the door’s edge so that the weatherstrip makes a tighter seal.
- Using metal shears or large scissors, cut pieces of spring metal for the top and the sides. On the piece for the hinge side, you may need to cut a notch for each hinge. Check if this is necessary by closing the door with a piece of the weatherstrip in each hinge.
- Using the nails given in the package, nail on the left and right side pieces, but not the top piece. For each piece, nail on the top end, stretch the weatherstrip down tightly and nail on the bottom end. Nail on the center of the piece, and then put in the rest of the nails. Drive the nails in just far enough to be flush, not enough to bend the spring metal. If the wood is slightly rotten at the bottom so the nail goes in easily, use longer nails there.
- Before mounting the top piece, cut its ends at an angle that will fit against the side pieces when they are bent outward. Nail on the top piece.
- Drive in twice as many nails as the instructions indicate. The doorjamb may have soft spots where nails have less strength.
- Carefully bend the weatherstrip out from the doorjamb enough to seal the gaps. Do not wrinkle it as you bend it.
Type 5 – Self-Adhesive Rubber Foam Weatherstrip Tape
Self-adhesive rubber foam weatherstrip tape has a solid, rectangular contour and is available in many widths and thicknesses. It has many names, it may be called, ”vinyl foam weather-seal self-stick tape”, “high-density rubber foam weatherstrip tape”, or “foam weatherstrip tape. “Low-density” tape has air pockets and is very compressible; “high-density” tape is much more durable. The name may not tell if it is high density or low density, so you may have to squeeze it to check if it is compressible. If the width you need are not available, you can buy a wider size and cut it with scissors.
Mount the Weatherstrip:
Rubber foam weatherstrip tape will fall off soon if stuck to a surface that isn’t clean, so prepare the surface by sanding it or scraping off the paint with a wood chisel. You shouldn’t wash the surface because you probably couldn’t dry it well enough for the tape to stick well. Even if the surface is well-prepared it will not stick long, maybe one or two years, but it will stay on longer if you staple or nail it on at its ends. If you don’t have a staple gun, nail it on with ¾” wire nails.
Door Sweeps and Weatherizing Door Bottoms
Door sweeps and weatherizing door bottoms attach to the door to seal the gap beneath it. Some are designed to prevent rain from entering.
Types of Door Sweeps
Conventional door sweeps have a rigid aluminum strip which holds a vinyl fin. The aluminum strip is screwed to the door, whether the door is wooden or metal. They are inexpensive, but they are not durable because the fin separates from the aluminum strip.
Two types of single-fin door sweeps are designed to be more durable. One has a thick vinyl fin that is clamped between an aluminum strip and the door by the mounting screws. These are available with an oak finish. Another type is similar to conventional door sweeps, but has a durable reinforced rubber fin. It is well-mounted to the fin.
Self-stick door sweeps have a vinyl fin that is held by a thin plastic strip, which is stuck to the bottom of the door. No screws are used, so these fall off before too long. Don’t mount one only because you have a metal door, any type of door sweep can be mounted to a metal door; drill pilot holes slightly larger than those recommended for wood. Metal doors are steel, so use a very sharp drill bit.
Brush door sweeps will seal the gap when the threshold or other surface below the door is irregular. In place of a vinyl fin they have plastic bristles. They may be the best choice when there is no threshold. They are not durable because their bristles fall off.
Flex-o-matic door sweeps are designed to clear thick carpets. They have two aluminum strips connect at a pivot joint and a vinyl fin below them.
Choose and Mount a Door Sweep:
- Check if the gap between the door and the carpet or floor becomes smaller as you open the door. On some old homes, this gap becomes much smaller as you open the door because the floor isn’t level. If your floor is un-level here, a door sweep with the widest available fin, or a flex-o-matic door sweep may be necessary.
- Buy a door sweep. If your door is wider than 36”, very few stores offer door sweeps that will fit it. You will probably need to buy two door sweeps.
- If the threshold is not directly under the door, so a door sweep would not contact it, buy a multi-fin bottom sweep. Some of the fins should contact the threshold. These are described below in.
- Carefully measure the width of your doorway, not the width of the door. Cut the door sweep to the width of the doorway. Your measurement may be slightly inaccurate, so it is safer to cut the bottom sweep slightly longer than your measurement, and check if this fits. Use a hacksaw to cut an aluminum or oak frame and scissors or a knife to cut a vinyl or rubber fin. If your doorway is wider than 36” and you will mount two door sweeps, cut each to half of the width of the doorway and mount each with three screws. This will be stronger than mounting a 36” door sweep and a short piece of a second door sweep.
- If there is no threshold and one will not be installed, mount a durable type of door sweep. Two are described above.
- To mount a door sweep onto a metal door, you can use the screws in the package. Drill holes in the door slightly smaller than the outer diameter of the screws, and screw them in using a cordless drill. The door is steel so the drill bits must be very sharp. Self-tapping screws are stronger but unattractive. They have hex heads, so to use them you must use a “nut driver bit” in a cordless drill.
- If the door is wooden and the bottom is slightly weak from rot, use 1¼” drywall screws to mount the door sweep, and drill extra holes in the door sweep for extra screws. These screws are designed to be used without drilling pilot holes. To prevent further rotting, take down the door by removing the hinge pins, sand the bottom surface with a belt sander, and paint this surface with exterior primer and exterior paint.
- After mounting and checking the door sweep, drill two holes in it and put in two more screws. The other screws are mounted through vertical slots that allow you to adjust the sweep, but the sweep could slide downward.
Types of Weatherizing Door Bottoms
Multi-fin bottom sweeps wrap under the door in either an L-shape or a U-shape. They have from 4 to 6 vinyl fins that sweep against the threshold. They are more attractive than conventional door sweeps because they are not as visible, and they seal the gap better than a single-fin door sweep, especially if the threshold is badly worn or not well-aligned with the door.
L-shaped multi-fin bottom sweeps have an aluminum frame and a vinyl bulb with very small fins on the bulb. Some L-shaped models cannot be seen from inside the house. Most, if not all have replaceable vinyl inserts which you can buy at a hardware store. L-shaped models are relatively thick, so you may need to saw off about ¼” from the bottom of your door. U-shaped models have a vinyl frame that wraps around the bottom of the door, with the fins attached directly to it. They are thin so you won’t need to cut the door. They are more visible than L-shape models but less visible than conventional door sweeps.
Pile weatherstrip can also be mounted to the bottom surface of a wood door to seal the gap. It is not visible and it is very durable if glued on correctly. Also, it can be used if the gap is very small. If the gap below the door is very small when the door is fully open, pile weatherstrip may be a good alternative. You can mount it using a router or circular saw to cut a notch in the bottom surface of the door. See “How to Choose and Mount Pile Weatherstrip”, below.
How to Choose and Mount a Multi-Fin Bottom Sweep
Measure the gap between the door and the threshold or floor. Measure it again with the door wide open. If the floor is not level, the gap below the door could be much smaller when the door is open, and the bottom sweep could prevent the door from opening. If the gap is very small when the door is open, you may need to use pile weatherstrip or a wide door sweep or a “Flex-O-Matic” door sweep. These are described above.
- Carefully measure the opening in the doorway, not the width of the door. Cut the bottom sweep to this length. Your measurement may be slightly inaccurate, so it is safer to cut the bottom sweep slightly longer than your measurement, and check if this fits. bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
- Mount the bottom sweep. If the door is metal, use either the screws provided or use self-tapping screws, which are stronger. To use the screws provided, drill pilot holes (using a sharp bit) almost as large to the outer diameter of the screws. If the door is wooden and the screws go in too easily, the wood is slightly rotted and the screws would fall out before too long. Use 1 ½ “ drywall screws and put in about three extra screws. To prevent further rotting, you could take down the door by removing the hinge pins, sand the bottom surface with a belt sander, and paint this surface with exterior primer and exterior paint. bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
- If your doorway is wider than 36” and you will mount two door bottoms, cut each to half of the width of the doorway and mount each with three screws. This will be stronger than mounting a 36” door bottom and a short piece of a second door bottom. bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
- After mounting and checking the bottom sweep, drill two holes in it and put in two more screws. The other screws are mounted through vertical slots that allow you to adjust the sweep, but these may allow the sweep to slide downward.
How to Choose and Mount Pile Weatherstrip
Pile weatherstrip is available in several sizes at window repair shops, up to ½” in fiber length, and only ½” is suitable for doors. The other sizes are for use on windows and storm doors. It can also be ordered on-line. Home centers and hardware stores only sell pile weatherstrip of much smaller fiber length called, “Storm Door and Window Pile Weatherstrip”. If you buy it at a window repair shop, ask them which epoxy to use. The groove in the door will be cut about as deep as the thickness of the base of the pile weatherstrip. Buy at least 4 ft. because you may use several 1” to test different types of epoxy.
Buy several brands of epoxy that bond vinyl or plastic, to test because the base of the weatherstrip may be polypropylene, and this is not listed on epoxy packages as a material that they will bond. It is necessary to test each brand by using it to glue a 1” piece of the weatherstrip to wood, and check if you can tear it off the next day.
Tools and Materials
- 1/2” pile weatherstrip
- circular saw or router
- ¼” wood chisel
- T-square or yard stick
- several brands of epoxy
Mount the Pile Weatherstrip
- Do not do the work on a very cold day because the door must be removed for hours while the epoxy dries.
- Remove the door by pulling the hinge pins. Set the door on sawhorses or a table.
- Use a router or a circular saw to cut a 1/16” deep groove in the surface of the door. A router will cut a groove of any width. If a circular saw is used, make two cuts and chisel out the wood between them. The surface at the bottom of the groove must be flat for the epoxy to adhere well.
- Glue in the pile and allow it to dry for the period of time given on the package. Do not use nails because temperature changes will cause them to slide out
A doorway must have a threshold to stop air from flowing under the door. Any type of weatherizing door bottom that is used without a threshold will wear out too soon.
Types of Non-Insulating Thresholds
Oak Saddle Thresholds – These are the conventional simple, wooden thresholds. They are called “saddle thresholds” because their bottom surfaces are shaped to contact the floor at either edge but not in the center to prevent rocking. They are all similar in height, about 1 1/16”. This can be a problem; a thinner or thicker threshold may be needed. They are more easily discolored by dirt than aluminum thresholds, and they eventually wear down in small areas, allowing small gaps.
Aluminum Thresholds – These are more durable than oak saddle thresholds and available in a wider range of heights, from about ½” to about 1¼”.
Oak and Aluminum Adjustable Thresholds – These have screws which you turn to control the thresholds’ height. Most available models can be adjusted from 1 1/8” to 1 3/8”. If the distance between the floor and your door is between about 1½ ” and 1 3/4 “, you could use an adjustable threshold to create a gap of the right size for the type of insulated door bottom on your door. If the gap is greater on one side of the door, the threshold can be adjusted for this. If the gap under your door is too large for an oak threshold, an adjustable threshold is a more attractive alternative than an aluminum saddle threshold. Adjustable thresholds are less durable than the other types.
Interior Wood Thresholds – These are oak and approximately ½” thick. There are at least two widths available, 2 1/2 “ and 5”. They can be used in an exterior doorway if necessary.
Types of Insulating Thresholds
Insulating thresholds are designed to contact the door to seal the gap. Most have a compressible weather seal, called a “vinyl insert”. The vinyl inserts are not durable, but they are easy to replace and are sold at hardware stores and home centers. The types shown below are available in the weatherization section of home centers and in many hardware stores and builders supply stores.
Oak Insulating Thresholds- These are more attractive than aluminum insulating thresholds, but not as durable because they have grooves for the vinyl insert. They are only available in heights of approximately 1”. With the vinyl insert, a 1” high threshold is about 1¼”. Their inserts are less available than the vinyl inserts in aluminum thresholds.
Aluminum Insulating thresholds- These have a removable vinyl insert. They are available in a wide range of heights, from about 3/4“ high to about 1 1/8” high, plus the height of the vinyl insert.
Adjustable Height Aluminum Insulating Thresholds – These have a separate piece of aluminum that holds the vinyl insert, which can be moved to different heights. One popular model can be adjusted from 1 3/8″ to 1 5/8″, plus the thickness of the insert. They are not durable as designed because the piece that holds the insert is supported by small, aluminum serrations which are not strong (see picture). You can make an adjustable threshold stronger by sliding in small blocks of wood before you mount it.
“Bumper Style” Insulating Thresholds – These have a vinyl weather seal that contacts the face of the door when it closes. They are unattractive, but may be suitable for basement and garage doorways where the appearance of a threshold is less important. They can be used when other types of insulating thresholds cannot be used because the gap is too small. If you have a metal basement or garage door with a small gap, you cannot cut the door to make the gap larger, so a bumper style threshold may be your only choice.
How to Mount a Threshold onto a Wooden Floor
Tools and Materials
- Handsaw for wood if oak threshold, hacksaw if aluminum
- Bevel and tape measure if you have no threshold to use as a pattern
- Cordless drill
- Crowbar and hammer to remove threshold
Mount the Threshold
- Remove the old threshold and carefully measure the space below the door at both sides. If the threshold is nailed down, use a prybar or crowbar. If the doorway did not have a threshold, measure the gap under the door at both sides of the doorway.
- Buy a threshold. Oak thresholds for exterior doorways are about 1 1/16” thick. Aluminum thresholds range from ½” to about 1 ¼” high. Ideally, the gap above the threshold should be 3/8”. If the gap will be much greater than this, a wide door sweep could be mounted.
- If you buy a threshold with a vinyl seal and you will not cut the door, check if the bottom surface is smooth. If it is not, remove the door and sand the surface with a belt sander. Paint it with primer and exterior paint to protect it from rot.
- If there is not enough space for a threshold, remove the door and saw it to allow a larger gap above the new threshold. Allow for a 3/8′ gap, unless you will mount a threshold with a vinyl seal. With these, the instructions tell what size gap the door should have. Paint the bottom surface with primer and exterior paint to protect it from rot.
- Using the old threshold as a template, mark the threshold to cut it. If the doorway did not have a threshold, check if the doorjambs are perpendicular to the threshold. If they are not, measure their angles with a bevel and trace them onto the threshold.
- Cut the threshold. Use a handsaw if it is wood, or a hacksaw if it is aluminum.
- If the threshold is oak, mount it with 3” finish nails. Drill pilot holes in the threshold to prevent it from cracking. Oak cracks more easily than pine. Do not drill the pilot holes close to the centerline of the threshold because the threshold could crack when you hammer in the nails.
- If the threshold is aluminum, drill pilot holes into the floor for the screws and screw down the threshold.
- If you are mounting an adjustable height aluminum threshold, set it in place with the door closed and adjust its height to the correct level, and then remove it. Cut several small blocks of wood to fit tightly into it, to prevent it from gradually falling.
- Apply clear exterior caulk around all sides of the threshold. This will prevent water from entering, freezing, and pushing up the threshold, and may prevent insects from entering.
How to Mount a Threshold onto Concrete
A threshold can be mounted to concrete in either of these three ways:
- Using a “powder actuated tool” with nails
- Using concrete screws
- Using screws and plastic anchors and using a hammer drill or compact hammer drill to make holes in the concrete for the anchors
Tools and Materials-(these depend on the method of mounting the threshold and the type of threshold)
- Wood or aluminum threshold
- Handsaw for wood if oak threshold, hacksaw if aluminum threshold
- Tape measure
- Cordless drill
- Small crowbar
- Polyurethane construction adhesive
- Clear exterior caulk
- Wire brush
- Small sledge hammer or framing hammer
- Drill bits for wood
- Package of 1/8” masonry bits
- 1/4” concrete screws and 3/16” bits for concrete screws
For All Methods of Mounting a Threshold
- Remove the old threshold with a crowbar or prybar.
- Use the old threshold to draw a pattern on the new threshold to cut it accurately. The old threshold may not have square corners because the door jambs may be at slight angles.
- If there is no threshold, measure the doorway to mark the threshold to cut. Check if the doorjambs are perpendicular to the threshold and if not, measure their angles with a bevel to trace onto the threshold.
- If necessary, cut the door to make space for the threshold:
a) Mark the door on its left and right sides where you will cut it. Mark both sides because the floor may not be level. Make the marks to allow a 3/8” gap above the new threshold, unless you are mounting a threshold with a vinyl seal. With these, the instructions tell what size gap the door should have.
b) Remove the door by pulling the hinge pins. Set it on a table or saw horses.
c) If you are mounting an insulating threshold, this surface will contact the vinyl insert, so it must be very straight and smooth.
d) Paint the bottom surface to protect it from rot.
- If you are mounting an insulating threshold and you do not cut the door, check if the bottom surface is perfectly straight and smooth. If a cut was made there when the door was hung, the bottom surface may not be straight enough If it is not, remove the door and sand the surface with a belt sander or a palm sander with coarse sand paper. Paint it to protect it from rot.
- Cut the threshold. Use a handsaw if it is wooden or a hacksaw if it is aluminum.
How to Mount a Threshold Using Concrete Screws
Concrete screws are driven directly into concrete with no anchor. A pilot hole must be drilled, but the pebbles in the concrete prevent you from drilling in about half of the places where you start holes and the pebbles quickly damage the bits damage the bits. Thus, only mount a threshold with concrete screws if you don’t have a hammer drill. With a hammer drill you can easily drill large holes for lead or plastic anchors and screw into the anchors.
To mount a threshold with concrete screws, buy three, flat head, ¼” concrete screws long enough to penetrate the threshold and enter the concrete by about 1”. Buy a package of four 3/16” masonry drill bits that are sold with the concrete screws.
- If the threshold is wood, drill three 3/16” holes through it (if it is aluminum it has holes). Do not drill the holes along the centerline of the threshold, drill them about ¾” from the centerline. The threshold is unsupported in the center and the force of the screws could crack it.
- Whether the threshold is wood or aluminum, hold the threshold firmly in position and using the holes as guides, drill a 3/16” hole into the concrete at each hole. Where the bit hits a pebble, drill at another spot. The pebbles are no more than 1” in diameter. A hammer drill cannot be used to make holes for concrete screws because it would make the holes slightly too large.
- If the threshold is wood, scrape the concrete surface with a wire brush and cover it with polyurethane construction adhesive. Lay the threshold and screw in the concrete screws.
- Caulk around all four sides of the threshold. This prevents water from entering, freezing, and pushing up the threshold, and may prevent insects from entering.
- If you mounted an insulating threshold that is slightly too high and the vinyl insert is forcefully compressed when you close the door, the vinyl insert will need to be replaced too often. Remove the door and remove 1/8” of wood from the bottom with a belt sander or plane.
How to Mount a Threshold Using a Powder Actuated Tool
Powder actuated tools use gun powder charges to shoot heavy nails.
- Shoot a nail into the concrete through each of the holes in the threshold. Use medium power level charges and nails just long enough to penetrate the concrete by ½” to ¾”. If a nail doesn’t enter far enough, hammer it with a small sledge hammer or large hammer such as a framing hammer.
- Caulk around all four sides of the threshold with clear, exterior caulk. This will prevent water from entering, freezing, and pushing up the threshold.
- Use a wire brush to clean the area where the threshold will be mounted. Apply polyurethane construction adhesive to the concrete. If the concrete is wet from rain or early morning dew, dry it thoroughly with a hair dryer before applying the adhesive.
- Drill two pilot holes for the nails at 1” from the center line. Drilling the holes here will prevent the nails from breaking the threshold. Using only two nails, supplemented by construction adhesive will reduce the risk of breaking the threshold.
- Shoot the nails into the concrete through the pilot holes. Use medium power level charges and nails just long enough to penetrate the concrete by ½” to ¾”. High power level charges could split a wooden threshold. If a nail doesn’t enter far enough, hammer it with a small sledge hammer or large hammer.
- Caulk around all four sides of the threshold with clear, exterior caulk. This will prevent water from entering, freezing, and pushing up the threshold.
How to Mount a Threshold Using Hammer Drill and Plastic Anchors
- Buy two 5/16” plastic anchors. Buy two screws of the diameter used with those anchors, long enough to go through the threshold and to the bottom of the anchors. Two are enough because the adhesive will provide extra strength.
- If the threshold is wooden, drill two 1/8” holes through it for two screws.
- Using an 1/8” masonry bit, hold the threshold firmly in place and drill through the holes into the concrete. These will be pilot holes to guide the 5/16” masonry bit.
- Remove the threshold and drill into the 1/8” holes with a 5/16” masonry bit. A hammer drill will break through most small pebbles in the concrete. Hammer in the plastic anchors.
- If the threshold is wooden, drill out the top of each hole for the screws’ heads to fit into.
- If the threshold is wooden, use a wire brush to clean the concrete, and apply polyurethane construction adhesive. If the concrete is wet from rain or early morning dew, dry it thoroughly with a hair dryer.
- Drive in the screws.
- Caulk along the four sides of the threshold with clear, exterior caulk.
How to Insulate Doors By Repairing the Doorways
To seal the leaks at an old doorway that has a rotted, warped or damaged door or door frame, you may need to repair the door or the door frame before mounting weatherstrip. Described below are different types of damage that cause leaks and how to repair them.
If the corner of a door has rotted away:
- Take down the door by removing the hinge pins. If the rotted area is less than about ½”, remove it completely using a belt sander or a wood shaver. Wood shavers cut wood cross grain better than conventional planes. Glue on cedar shims to replace the rotted wood. bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
- If the missing and damaged area is greater than about ½”, this will be on the bottom surface. Saw off a triangular piece of the door at the bottom to remove the rotted area. Make the cut perfectly straight to prevent water from entering because the water could freeze and break off the patch or it could allow rot to grow. If the wood is still slightly soft from rot after you have cut off the rotted area, coat the bare surface with wood hardener to create a stronger surface to glue to. Wood hardener is sold in paint departments. bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
- If you scraped off the rotted area, cut one or two pieces of shim and glue them to the bottom of the door to fill the gap. If you have a bundle of cedar shims, use shims from this because cedar resists rot relatively well. Cedar shims may only be available in large bundles for about $10. They are used mainly as shingles, and they may be called shingles. Glue on the piece or pieces of shim with polyurethane construction adhesive. This is very strong and it fills small gaps in the wood, which carpenter’s glue does not do. Drill two pilot holes in the shims for nails and nail in two ¾” or 1” wire nails to hold the shims in place until the adhesive dries. bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
- If you sawed off the rotted part of the door, replace it with a triangular piece you cut from a scrap door if one is available. Wood of the thickness of a door (1 3/8”) is not sold. You could instead cut a 2”x4” board to 1 3/8” thick, and cut the triangular patch from this. A table saw would do this much better than a circular saw. It is best to paint the surface of the door where you made the cut and paint the surfaces of the patch, and allow the paint to dry fully before attaching the patch. The paint will prevent water from entering the pores and causing rot. The best way to attach the patch piece is with ½” wooden dowel rods, because screws expand and contract, causing a crack where the new piece meets the door. If dowel rods will not be used, use wood screws. If you use wood screws, drill holes for them in the patch piece which are as large in diameter as the screws. The screws will then clamp the patch piece strongly to the door. bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
- If the door frame moves at the bottom when you close the door, the wall’s framing is probably nailed to a concrete floor and the nails have rusted away. To repair it, remove a section of the interior wall to expose the board that rests on the concrete floor. Nail it to the floor using a sledge hammer and masonry nails, or a powder actuated tool. bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
- If the threshold or the bottoms of the doorjambs or the bottom of the door are badly damaged by rot, check if the area is under water in a hard rain. If it is, the wood will continue to rot or warp after you repair it, so try to correct the problem. First, check if any nearby drains are clogged, and have them unclogged. Next, check if the rain gutters and downspouts are working correctly. The gutters may be clean, but overflow with water because they sag in the middle. You can check the rain gutters and downspouts either by watching them when it rains or by running a garden hose to the roof and filling the gutters with water. In some homes, water runs through the yard toward the house in a hard rain. You can correct this by adding soil near the house. bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
- If a door is badly warped, it is probably a door designed for interior use. You should replace it. This is probably not a project for a do-it-yourselfer who has never done it. Wood must be cut away for the hinges, the door must be cut to fit perfectly, and the lockset must be installed- skills that take practice. If the door will not be replaced and its bottom corner can be bent back to fit into the door frame, you could seal the gap by mounting a heavy slide bolt onto the bottom corner of the door and closing it with the door bent into place. Mounting thick weatherstrip to seal a large gap would not seal it for very long because the door will continue to warp. bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
- If a corner of a basement door was chewed off by rats, repair it with sheet metal. The appearance of this could be acceptable on a basement door. Aluminum sheet metal, called “flashing”, is sold in rolls at home centers and hardware stores. Fold a piece of this around the corner like wrapping a package, and attach it with 1” self-tapping screws or 1 ¼” drywall screws. Shorter screws may not hold because the wood may be weak from rot. bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb
- If the bottom inch of a door is badly rotted, wrap sheet metal around it and mount it with 1” self-tapping screws or mount on a large L-shape door bottom. Mount the U-shaped door bottom with 1” or 1 ¼” screws; the wood is too weak for shorter screws. Drill several holes in the U-shaped door bottom to put in more screws than it was designed for.
If the bottom of a doorjamb is badly rotted, there are several ways to repair it or only seal the leak.
- To only seal the leak, shoot “minimum expanding” expanding foam sealant into the empty space. After it dries, cut it to be flush with the doorjamb. The rot may not spread. It was caused by rain water at the bottom of the doorjamb “wicking up” into that section of the wood. The wood will dry out after the water has been blocked, and the fungus causing the rot will die.
- Repair the rotted area with wood filler. Wood filler will eventually fall out because it doesn’t expand and contract exactly the same as wood with the changes in temperature, but if you paint it well it will last longer. Use wood filler only if the wood behind the rotted doorjamb is solid. It must also be dry, and it could remain wet for days after a rain.
Thoroughly remove the rot-softened wood with a scraping tool and wire brush, or by sawing off the bottom inch of the doorjamb. Apply wood hardener to the area that was scraped or sawed. This makes the surface hard for a better bond. It is sold in paint departments. Wood filler can be applied with a 4” plastic putty knife. When the putty has dried, paint it well to prevent water from entering between the putty and the wood. If the old paint on the frame is oil base, you must use oil base paint, and if it was painted with water base paint you must use water base paint.
- If the rotted section is no greater than a few inches high, saw off that part of the doorjamb and replace it with a piece of wood that is cut to fit. If the house is very old and it is a basement doorway, the doorjamb is probably nailed directly to masonry with three or four very large nails. Do not make the cut above the lowest of these nails because the doorjamb would loose strength. If the doorjamb is nailed to wooden framing and you must remove the wood above the lowest nail, first screw in two or three 3½” framing nails to strengthen the doorjamb. Cut a piece of wood into the shape and size of the rotted piece, to replace the wood that was removed. It is best to use cedar because this is much more rot-resistant than pine. If you use pressure treated wood, it cannot be painted for months, and you must use solid color stain, and buy a gallon.
You must paint the ends of the patch piece before gluing it in-this is where water would enter the wood. Dip the patch piece of wood into a can of exterior paint to fill its pores with paint, and allow it to dry thoroughly before gluing it in. Also, thoroughly paint the surface of the old doorjamb where you have cut. Glue in the patch piece with polyurethane construction adhesive. This will fill the gaps like caulk. Caulk the edge thoroughly where the piece of wood rests on the ground.
- If a large section of the doorjamb must be replaced, check if it is nailed directly to a masonry wall. This is common for basement doors of very old houses. If so, you should replace the entire doorjamb because all of the hinges should be mounted to the same board. If the doorjamb is nailed to wooden framing, you can replace just the rotted section. To replace either the whole doorjamb or a shorter piece, you must use a 2”x8” or 2”x10” board and cut it to the shape of the piece you have removed. You cannot buy doorjamb stock to match very old doorjambs.
Basement doorway doorjambs nailed to masonry walls were normally a 2”x8” or 2”x10” board with a 1/2 “ notch for the door’s edge. You must use a table saw to cut the notch. Before mounting the board, thoroughly paint the bottom end to prevent water from “wicking in”. Mount it using long, ½” lead lag shields with ¼” lag screws. Mount the lag shields between the bricks. Buy a package of shims and use these to mount the doorjamb in the correct position. If the doorjamb is nailed to wooden framing and you are replacing just the rotted section, mount it with 3” framing screws. Put shims behind it to mount it correctly. Carefully caulk all around the new doorjamb, and mount weatherstrip to it.
So, try to be handy and use How Insulate Doors and Repair Doorways to make your doorways air-tight and your heating bills lower!