Drafty Front Door? How to Find the Leak and Fix It

When cold air pours in around an exterior door, the door itself is rarely the first thing that needs replacing. Most drafts come from a worn seal, a sweep that no longer touches the threshold, or a door that has sagged out of line. Those are usually small, inexpensive fixes. This guide walks through how to find exactly where the air is getting in, what to fix first, and when a door really has reached the end of its life.

TL;DR

• Find the leak before you buy anything. Look for daylight, feel for moving air, and try the dollar-bill test.

• Fix the fit first. Loose hinges and a shifted strike plate can open gaps that no weatherstripping will close.

• Replace worn weatherstripping on the sides and top, and make sure the bottom has a working sweep.

• If your threshold has adjustment screws, raise it until the light disappears, but not so far that the door drags.

• Replacement makes sense when the slab is warped, the frame or sill is soft, or drafts come right back after new seals.

Why a small gap matters

A door is a big opening that moves every day, so its seals wear out faster than almost anything else on the outside of a house. This Old House notes that a 1/8-inch gap around a door's perimeter can let in as much air as a small window opened halfway. That is easy to miss until a windy January night.

Drafts are not only about comfort. The Department of Energy's Building America Solution Center explains that air leakage through narrow gaps around windows and doors can let in dust, pollen, insects and noise, and causes heating and cooling losses that show up on your utility bill.

Step 1: Find where the air is getting in

Do this on a cold, windy day if you can, because leaks are easiest to notice then. The Building America guide lists a few simple checks:

• Feel for it. Run your hand slowly along the top, both sides and the bottom of the closed door. A tissue held near the edge will flutter where air is moving.

• Make the house pull air. Close all windows and exterior doors, then turn on every exhaust fan, such as bath fans and the range hood. That pulls air in through any gaps, which makes small leaks easier to feel.

• Look for light. At night, turn on the porch light and turn off the lights inside. Any light around the door means outside air can come in the same way.

• Try the dollar bill. Close the door on a bill at several spots along the frame. If it slides out easily, the seal is not tight there.

This Old House uses a smoke stick to spot leaks at the bottom of a door. Hold it near the closed door and watch where the smoke gets pulled inward.

Write down where you found the gaps. Top corner on the latch side, bottom only, or all the way around each point to a different fix.

Step 2: Fix the fit before the seals

If the door does not sit evenly in its frame, new weatherstripping will only hide the problem for a while. The Department of Energy's weatherization job aid says to adjust loose hinges, knobs and strike plates before you install weatherstripping.

Signs the door has shifted:

• The gap between the door and the frame is wider at one corner than the other.

• The door rubs near the top on the latch side, or you have to push hard to latch it.

• The latch hits the strike plate instead of dropping into the hole.

Family Handyman's fix for a sagging door starts with tightening every hinge screw by hand, using a screwdriver rather than a drill so you don't strip the holes. If that isn't enough, replace one jamb-side screw on a hinge with a 3-inch screw that reaches the wall framing and draws the jamb in. To fix a door that won't latch, Family Handyman suggests doing this at the top hinge to raise the latch, or the bottom hinge to lower it. Watch the trim as you tighten and stop if the joints start to open.

Step 3: Replace worn weatherstripping on the sides and top

Weatherstripping is a wear part. This Old House lists the signs that it is done: cracks, tears or missing pieces, light around the edges, drafts on windy days, and material that has gone hard and brittle instead of staying soft and compressible.

Start by checking what kind you have. The Building America guide notes that newer doors have a groove (kerf) cut into the frame that holds a formed gasket, while older doors without a groove use foam tape or metal-and-vinyl strips screwed in place. Family Handyman points out that steel entry doors often use a compression strip on the hinge side and a magnetic strip on the latch side and top, so look closely before you buy a replacement.

A few tips that help it last:

• Pull out the old strip and clean the surface with dish soap and water. Let it dry completely.

• Measure each side and the top separately, and cut pieces to fit.

• After installing, open and close the door several times. It should close and latch without forcing it. A seal that is too thick makes the door hard to latch and wears out quickly.

Step 4: Seal the bottom of the door

The bottom is where most people feel the cold, and there are two parts working together: the threshold on the floor and the sweep or door bottom on the door.

Adjust the threshold

Many newer entry doors have an adjustable threshold with a row of large screw heads. Family Handyman explains that those screws raise or lower a strip in the threshold. Turn them counterclockwise to raise it where you see light, use a straightedge to keep the strip level, and check again. A small sliver of light at the very corners is normal. Don't raise it so high that the door presses hard against it, because a tight fit wears out the seal fast.

Replace or add a sweep

If the threshold is set right and air still gets in, the sweep is likely worn. Family Handyman shows how to install a screw-on door sweep: cut it to the width of the door, set the flexible part lightly against the threshold, drill pilot holes and fasten it.

This Old House recommends a brush-style sweep for a threshold that isn't level, because the bristles follow the uneven surface. An automatic door bottom, which drops a gasket when the door closes, only seals well against a flat surface.

If the threshold itself is cracked, loose or rotted, it needs to be replaced. That is a bigger job than a sweep, since the door may need to come off and the sill underneath should be checked for water damage.

Don't forget the door to the garage

The Building America guide calls out the door between the house and an attached garage. Weatherstripping that door matters for more than comfort: it helps keep garage fumes out of the house.

When the leak is around the frame, not the door

Sometimes you feel cold air at the trim rather than at the edge of the door. The Building America guide says that if a frame feels much colder than the wall around it, the gap between the frame and the wall framing may never have been insulated and air sealed. Caulk the seams in and around the trim, and if that doesn't help, the trim may need to come off so the gap behind it can be sealed. If you see water stains or soft wood near the opening, our guide to water leaking around a window covers the same kind of detective work for leaks that come from outside.

Repair or replace the door?

Most drafty doors only need the fixes above. Replacement is worth a look when:

• The slab is warped or bowed and won't sit flat against new weatherstripping.

• The frame, sill or bottom of the door is soft or rotted. Press gently with a screwdriver. Wood that gives way is holding water.

• The draft comes right back after new seals and adjustments, which means the door or frame no longer sits square.

• A steel skin has rusted through or a fiberglass or wood door has cracked deeply.

If you do replace a door, look for the ENERGY STAR label. ENERGY STAR says certified doors are independently tested, certified and verified by the National Fenestration Rating Council and meet efficiency guidelines set by the EPA. Ask to see the NFRC ratings for the exact door you're considering. Our guide to reading energy efficient window labels explains what those numbers mean.

If the new door is a different size or the opening has to change, check with the City of Omaha Permits & Inspections before work starts.

Our perspective

A drafty door is one of the most common winter complaints, and it's usually the easiest to solve. Find the leak first, fix the fit, then replace the seals. That order keeps you from spending money on a new door when a few screws and a strip of weatherstripping would have done the job, and it tells you clearly when the door really is finished.

Need help in Omaha?

Spagnotti Contracting repairs and replaces entry and patio doors across the Omaha metro, including weatherproofing, trim and casing. You can read about our window and door service, see all of our services, or contact us with questions. We don't publish a door price list, because the work depends on the size, style and condition of each opening.

If your windows are fogging up this winter too, our guide to window condensation inside explains what's normal and what isn't.

FAQ

Why is my front door drafty even though it's fairly new?

New doors still rely on seals and a properly adjusted threshold. A threshold set too low, a sweep that doesn't touch, or hinges that have loosened can all let air in. Check the fit and adjust the threshold before assuming the door is defective.

How do I know if my weatherstripping needs to be replaced?

Look for cracks, tears, flattened or missing sections, and material that has gone hard. Light around the edges or drafts on windy days are the other signs.

Can I fix the gap under my door myself?

Often, yes. If your threshold has adjustment screws, raising it can close the gap in a few minutes. Otherwise, a new screw-on or brush-style sweep is a manageable project for most homeowners.

Should I replace a drafty door?

Only if it's warped, rotted, rusted through, or the drafts return after new seals and adjustments. Otherwise, repair is usually the better value.