Most front door drafts are fixed with new weatherstripping, a new sweep and a threshold adjustment, in that order, for the price of a hardware-store kit. The rest are a door or frame that has moved, a gap behind the casing that was never foamed, or a door that leaks heat through the panel itself. This applies to any entry door in a Minnesota house, wood, steel or fiberglass.
Stand by the door on a windy January day and you can trace the leak with your hand: the latch side, under the sill, a top corner, the edge of the trim. Each one has a cause. Here is the same order a service visit checks, cheapest fix first.
Where is the draft coming from?
On a cold or windy day, run your hand slowly around the door and note where you feel air. A lit incense stick works too; the smoke bends at the leak. The usual spots, and what each one means:
| Where you feel it | Likely cause | Fix |
|---|---|---|
| Latch-side edge, full height | Worn or flattened weatherstripping | New kerf-in weatherstrip |
| Under the door | Worn sweep or a threshold that has dropped | New sweep, adjust or replace threshold |
| Top corner on the latch side | Door has sagged on its hinges | Long screw through the top hinge, shim hinges, move strike |
| Around the casing, at the trim edge | No insulation in the gap between frame and framing | Pull the casing, low-expansion foam, reinstall |
| Through the panel, cold everywhere | Uninsulated wood or hollow door, or steel with no thermal break | Replace the door |
| Bottom corners, plus soft wood | Rotted jamb bottom or sill | Cut out and patch the jamb, or replace the unit |
Why is weatherstripping the highest-value fix?
Most doors seal with compression weatherstripping pressed into a slot, the kerf, in the door stop. It compresses thousands of times, hardens with age and sun, and stops springing back. Replacement kerf-in weatherstrip is cheap, roughly $20–$40 for a door kit by published hardware-store prices, and takes minutes per side once you have the right profile. If the old strip is flat, cracked or painted stiff, this is the first move.
Take a piece of the old strip to the store. The common profiles are a foam-filled fabric bulb, a hollow vinyl bulb, and on steel doors a magnetic strip on the latch side that grabs the skin. Press the new strip in starting at the top and do not stretch it. Close the door on a strip of paper at several heights; if the paper slides out freely anywhere, the strip is not touching there and the door or frame has moved.
How do you fix a draft under the door?
Light under the door means the sweep is worn or the threshold has dropped. Screw-on and slide-in sweeps are simple swaps; match the style, since a fin sweep for an adjustable sill and a flat sweep for a fixed one are not interchangeable. Most thresholds adjust: four or five screws along the sill cap raise or lower it until it just touches the sweep. Gentle contact is the target. A threshold cranked too high wears out the sweep and makes the door drag.
Look at the corner seal pads too, the small foam blocks at the bottom of each jamb where the sweep meets the weatherstrip. They fall off and nobody notices, and the corner leaks. They cost almost nothing to replace. If the threshold itself is rotted, split or the sill under it has dropped, adjustment will not hold and the threshold gets replaced.
What if the draft is around the trim, not the door?
Cold air at the edge of the casing, or a cold stripe on the wall next to the door, is not the door at all. It is the gap between the door frame and the rough opening, which on an older install was stuffed with a little fiberglass or left empty. Wind gets into that gap from outside through the siding joint and comes out at the trim.
The fix is to pull the interior casing, fill the gap with low-expansion window-and-door foam in a thin bead, let it cure, trim it flush and put the casing back. Standard foam bows the frame and binds the latch, so use the low-expansion kind. On the outside, check that the brickmould is caulked to the siding and that there is a drip cap or flashing at the head. If that gap was never sealed, the door frame has also been sitting in a cold, damp cavity for years, so look hard at the jamb bottoms while the casing is off.
When is the door itself the problem?
If new weatherstripping still will not seal, the door or frame is warped, sagging or out of square. The tells: uneven reveal around the door, a deadbolt that fights you, daylight at one corner but not the other. Shimming a hinge, driving a long screw through the top hinge into the framing, and moving the strike recover small misalignments. A warped slab or racked frame defeats every gasket you put on it.
Old doors also leak through the panel itself. An uninsulated wood slab or a hollow-core door conducts cold straight through with no gap required, and so does an old steel door with no thermal break at the edges: the inside face frosts, sweats and drips, and the puddle rots the threshold. A modern door has a polyurethane foam core, a thermal break on steel skins, and insulated low-E glass in any lite. No amount of weatherstrip turns an old panel into that.
When should you stop patching?
If the door is warped, rotted, uninsulated or over 25 years old and it has already had new weatherstripping once, stop. A prehung insulated entry door brings a new frame, kerf-in compression weatherstripping, an adjustable threshold with a matched sweep, a foam-core slab and, when it is installed right, a sill pan, low-expansion foam in the gap and an interior air seal. It seals as one system and pays you back in comfort every day of a Minnesota winter.
Not sure which you have? Send three photos: the door from outside, the bottom of the jamb on both sides, and the latch edge with the door open. you hear back from us within one business day, and if a weatherstrip kit is all you need, that is what you will be told.
What JMB Builders does
JMB Builders is a licensed Minnesota residential building contractor (BC809005) based in Zimmerman, working across the Twin Cities metro. Small repairs and full replacements both, priced per door, on any brand of door. Paid by check or direct deposit. Call 763-204-2099 (text) or send photos through the site.
- Door sweep and weatherstripping replacement — jmbbuildersmn.com/services/doors/door-sweep-and-weatherstripping
- Exterior door threshold replacement — jmbbuildersmn.com/services/doors/exterior-threshold-replacement
- Rotted jamb bottoms on exterior doors — jmbbuildersmn.com/services/doors/exterior-door-jamb-bottom-rot
- Labor-only installation of a new entry door you bought — jmbbuildersmn.com/services/finish-carpentry/door-installation-labor-only
Frequently asked questions
How do I stop a draft under my front door?
Replace the sweep on the bottom of the door, then adjust the threshold up until the sill cap just touches the new sweep. Most thresholds have four or five adjustment screws along the top. Replace the corner seal pads at the bottom of each jamb while you are there. If the threshold is rotted or the sill has dropped, the threshold itself gets replaced.
How do I replace the weatherstripping on a front door?
Pull the old strip out of the kerf, the slot in the door stop, and press the new strip in starting at the top. Take a piece of the old strip to the store to match the profile. A kit runs roughly $20–$40 by published hardware-store prices and takes minutes per side once you have the right one. If the new strip still does not seal, the door has moved.
How do I adjust a door threshold?
Most thresholds have four or five screws along the top of the sill cap. Turn them to raise or lower the cap until it just touches the sweep with the door closed. Too high and the door drags and the sweep wears out fast. Too low and you see light.
Why does my front door leak air at the top corner?
The door has sagged on its hinges, so the latch-side top corner no longer meets the weatherstrip. Driving a long screw through the top hinge into the wall framing often pulls it back into line. If not, the hinge gets shimmed and the strike moved to match.
Why is it cold around the door frame but not at the door?
The gap between the door frame and the wall framing was never insulated, or was stuffed with a little fiberglass that wind blows through. Pull the interior casing, fill the gap with low-expansion door-and-window foam, and put the casing back. Check the exterior caulk at the brickmould and the head flashing while you are at it.
Is it worth replacing a drafty wood front door?
If the slab is uninsulated wood or hollow, it leaks heat straight through the panel with no gap at all, and no weatherstrip fixes that. If it is also warped or rotted at the bottom, new weatherstripping will not hold. A prehung foam-core door with compression weatherstripping and an adjustable sill is the fix at that point.
