Draftproofing a door

A few simple steps will make your front door more energy efficient

Draftproofing a door can have almost as much of an impact as installing a new energy efficient front door. If you can feel a lot of cold coming through your front door in winter, a few simple steps can cut both your heating costs in winter and your cooling costs in summer. A new ENERGY STAR door could cost you $1500 or $3500 (along with $500-900 for the installation). If that’s outside your budget, or if there are other energy efficiency upgrades (like a high efficiency heat pump) that make more sense for the big bucks, draftproofing a door with some weatherstripping, a threshold, and a few simple changes can cut most of the heat loss out for far less.

A snug fit is key

The first step in draftproofing a door is to make sure the main door fits relatively snugly against the door frame. If there are gaps at the sides or top or bottom, you’ll likely get drafts there. I once discovered a half-inch gap between my front door and the doorframe. It turns out my contractor trimmed the door in the process of installing new tile flooring in the front hall. He didn’t need to trim a half-inch but I guess he got carried away. I cut a 3/8″ strip of hardwood flooring to the right thickness and screwed that into the bottom of the door, which substantially cut down on drafts. The bottom of the door looked a little odd, but people didn’t generally notice. (I’ve since upgraded to an ENERGY STAR door.)

Check the moulding around the interior when draftproofing a door. You may have a good seal in the doorway itself but air may be sneaking through the walls and out the edges of the molding. Use a product like DAP Alex Plus caulking to run a bead along the joint between the moulding and the wall. This should help reduce drafts from there. On a cold day, try turning on any indoor exhaust fans you have to draw warm air out of the house and cold air in, and use your fingers to feel for any strong drafts in the moulding; seal them as well. For under $10 worth of caulking and 10 minutes of your time, you can make a big difference here. If air leaks are really bad around the moulding you may not have enough (or any) insulation in the walls around the door, in which case consider injecting an inexpensive spray foam insulation into the wall cavity – just drill tiny holes big enough for the spray foam nozzle, and inject enough foam to fill. This should make a big difference not only to the drafts but to the lack of insulation in the wall. (If you have a bigger problem of no insulation anywhere in your walls, call in the pros!)

Keep the letter carriers out!

If you have a mail slot in your door, as many older homes do in my neighborhood, one of the best ways of draftproofing a door is to seal the mail slot opening off and put an outdoor mailbox on your outside wall instead. It’s amazing how much cold air can seep in through even a closed mail slot. The same applies to a rotary manual bell on the door (where an outside brass handle turns a ringer on the inside), or any other hole in the door itself that hasn’t been properly sealed, such as an old keyhole. Also if there are old cut-outs in the side of the door, or the doorframe, for a latch that’s no longer used, fill them in with a durable plastic wood product.

Windows inside doors

If you have a window in the door itself you’re likely losing quite a bit of heat through the frame for the window, or, if the glass is leaded, through the gaps in the lead came. Draftproofing a door with an old window in it really starts with the window. For leaded glass, the first thing you should do is look for places in the lead came where it’s not snug against the glass. You can often just push the came back in place by rubbing back and forth with the end of a wooden spoon. Even placing a little transparent caulking in gaps in the came can help. If there’s room in the window frame within the door, consider getting a piece of glass cut to the size of the opening, and use 3/8″ moulding to hold the glass in place over top of the leaded glass (and use clear caulk around the moulding).

The door latch

Make sure your door closes tightly. If you’ve recently changed your lock mechanism it’s possible that the latch is no longer properly aligned with the latch plate, which can cause the door to shut almost all the way but not quite. That will let drafts in. It’s also possible in an older door that the latch plate may have slipped (if the latch plate screws aren’t gripping right, or the wood the latch plate is screwed into has deteriorated) in which case you should remove the latch plate, put some durable plastic wood in the screw holes, and drill new holes that allow the latch plate to hold the door more tightly closed. Finally, look for obstructions that prevent the door from closing fully, such as raised nail heads, crumpled weatherstripping, a broken section of doorframe where the wood juts out, or a warp in the door or doorframe wood. (If the door itself is warped, you may not have much choice but to replace it.)

Weatherstripping and a threshold

Draftproofing a door can make a big difference to your front door energy efficiency if you include installing a door threshold (sometimes called a bumper threshold) at the base of the doorway, and a weatherproofing door kit for the sides and top. The threshold screws into the bottom of the doorframe, and provides a strip of rubber or other flexible weatherstripping across the base of the door. You install it so that when the door is closed the weatherstripping presses against the door and seals the bottom off. The weatherproofing door kit does the same thing for the top and sides. The bumper threshold is almost always sold separately from the weatherstripping. You can also get a door sweep instead of a bumper threshold – it attaches to the underside of the door instead of to the base of the door frame. The only problem with door sweeps is that because they are rubbing against the floor every time the door opens or closes, they are more quickly worn out (on the other hand, people don’t step on them every time they walk through the door!)

You’d be spending around $20-40 for threshold and trim kit combined – a very cheap way of draftproofing a door. These kits can have a payback, in terms of energy savings, of as little as two months.

If you’re draftproofing a door in a rental house, and don’t want to tamper with the construction of the doorway, or you just want to go the extra mile, you can also stop air leakage from the base of a door with a store-bought draft guard (sometimes, entertainingly, called a draft dodger) or a home-made bean bag – just shove it at the base of the door when you close up for the night. To make one yourself, cut a length of (attractive!) cloth 6 inches longer than your door is wide, and about 9.5 inches wide. Fold in half along its full length, decorative side in, and sew the seams shut at one end and along its length. Turn it decorative side out, fill with dry soy beans, white navy beans, cherry pits, whole barley or whole oats, or some other dry, hard seed (you’ll need about 8 cups worth), then sew the other end shut. Even just rolling up a towel and placing that along the base of the door will help, though it won’t work as well or look as good. But I do recommend staying away from the product known as the Twin Draft Guard, which slides under your door and provides draft guards on either side, as judging from the range of reviews (50% of customers very satisfied, 50% very unhappy) it has some quality issues.

The storm door or screen door

When draftproofing a door, don’t forget the screen or storm door. A screen door with just a bug screen on it should be replaced by a true storm door, while even a good storm door can be a source of air leakage. If it has movable window panes, check that they are fully closed. If you can feel air leaking around the edges of the window panes, you may be able to cut down on drafts by using clear removable caulking, which can be peeled away in the spring when you want to raise the glass to let air flow into your house. If you feel air leaking around the edges of the door itself, some of the same techniques mentioned above for the main door can help: adjust the latch plate so the door closes firmly; make sure the door isn’t warped; check that the hinges are well attached to both the frame and the door. For a screen door with a hydraulic closing mechanism check that the mechanism isn’t blocked from fully closing (for example by the lock bracket on the hydraulic piston axle that’s used to keep the door open).

Payback in as little as two months!

In general, draftproofing a door is a much cheaper approach than buying a new ENERGY STAR door, if you just want to cut down on heat loss and uncomfortable drafts and don’t have a big budget. If your door has major structural problems, or you want to replace it for aesthetic or security reasons, or you have $2500 to spare to get the ultimate in door energy efficiency, then a new ENERGY STAR door may well be the right choice. But draftproofing a door can take you much of the way to the benefits of a new dor. For $50 or less in materials and a half hour or so of your own time installing draftproofing materials, you can wipe out most of this air leakage, and it will make a big difference in your home comfort and home heating bills.

And you’ll have $2,450 left over to spend on something you really need.