Draft runs across the whole bottom
You feel air all the way across, or you can see a thin line of light from corner to corner.
Start here: Check the front door sweep for wear, flattening, or missing contact with the threshold.
Front door draft troubleshooting
Door Draft Under Front Door
Direct answer: A draft under a front door is usually caused by a worn door sweep, a threshold that sits too low, or a door that has dropped enough that the bottom seal no longer touches evenly.
Most likely: Start by checking whether the gap is even across the whole bottom edge or only wider on the latch side or hinge side. An even gap points to the front door sweep or threshold. A crooked gap points to alignment.
Stand inside on a cold or windy day and look at the bottom edge with the door closed. If light shows through all the way across, think seal or threshold first. If the gap changes from one side to the other, think sagging hinges or a door that is out of square. Reality check: a small draft can come from a surprisingly small gap. Common wrong move: replacing weatherstripping on the sides when the air is clearly coming from the bottom.
Don’t start with: Do not start by caulking the threshold or stuffing the gap with foam. That hides the symptom and usually makes the door drag or trap water.
Even gap across the bottomCheck the front door sweep and threshold height first.
Gap wider on one sideCheck hinge screws and door alignment before buying any seal parts.
Last reviewed: 2026-04-05
What the draft under the front door looks like
Draft is stronger on the latch side
The gap is larger near the handle side, and the door may look slightly dropped.
Start here: Check for loose top hinge screws and a door that has sagged in the opening.
Draft is stronger on the hinge side
One bottom corner seals but the other does not, often with a crooked reveal around the frame.
Start here: Check alignment and look for a twisted slab, loose hinges, or a shifted threshold.
Draft started after threshold or flooring work
The door used to seal, then started leaking air after a threshold change, new flooring, or seasonal movement.
Start here: Check whether the threshold sits too low or the door sweep no longer reaches it.
Most likely causes
1. Worn or compressed front door sweep
This is the most common cause when the gap is fairly even and the draft is strongest right at the bottom edge.
Quick check: Close the door on a flashlight or paper strip at the bottom. If it slides freely across most of the width, the sweep is not sealing.
2. Front door threshold set too low or out of position
If the sweep looks intact but never touches the threshold, the seal cannot do its job.
Quick check: Look from the side with the door nearly closed. You should see the bottom seal just meet the threshold, not float above it.
3. Sagging front door from loose hinges
A dropped door opens a wedge-shaped gap, usually larger at the latch side bottom corner.
Quick check: Compare the gap around the top of the door. If the top reveal is tighter on the latch side, the door has likely sagged.
4. Warped door slab or shifted opening
If the bottom seal touches in one area but not another even after hinge tightening, the slab or opening may be out of plane.
Quick check: Sight along the closed door edge and look for a bow, twist, or corners that do not sit in the same plane.
Step-by-step fix
Step 1: Confirm where the air is actually entering
Bottom drafts get blamed on the wrong part all the time. You want to separate a true under-door leak from air coming around the frame and washing down to the floor.
- Close and latch the front door fully.
- On a cold or windy day, move your hand slowly along the bottom edge, then up both side jambs.
- Look for visible light under the door from inside with interior lights off if needed.
- Use a thin paper strip at several points along the bottom to feel where resistance is missing.
- If the strongest air is really coming from the sides or top, treat this as a frame weatherstripping problem instead of a bottom-gap problem.
Next move: You have the leak location narrowed down to the bottom edge, one bottom corner, or the frame instead. If you cannot tell where the air starts, wait for a colder or windier time and check again with the room quiet and the door fully latched.
What to conclude: A true under-door draft usually points to the sweep, threshold, or alignment. Air around the frame is a different repair path.
Stop if:
- The door frame is visibly loose in the wall.
- You find water staining, rot, or soft wood at the threshold or jamb.
- The draft is tied to a larger framing gap you can see moving.
Step 2: Check whether the bottom gap is even or crooked
This is the fastest way to separate a seal problem from an alignment problem.
- With the door closed, look at the gap under the slab from inside and outside if possible.
- Compare the bottom gap at the hinge side, center, and latch side.
- Check the reveal at the top of the door too. A tight top corner on the latch side often goes with a sagging door.
- Open the door halfway and lift gently on the handle side. If you feel play, the hinges or screws may be loose.
- If the bottom gap is even, stay focused on the sweep and threshold. If it is uneven, move to hinge and alignment checks first.
Next move: You now know whether to chase sealing parts or door alignment. If the gap looks inconsistent but not clearly sagged, inspect the threshold and door slab for warping before buying anything.
What to conclude: Even gap means the door is mostly hanging correctly. A wedge-shaped gap means the slab has shifted or dropped.
Step 3: Inspect the front door sweep and threshold contact
A bottom seal can look fine from a few feet away and still be too flattened, torn, or short to block air.
- Open the door and inspect the front door sweep along the full width.
- Look for torn vinyl, missing fins, flattened rubber, hardened material, or sections that no longer spring back.
- Clean dirt off the threshold and the bottom seal with warm water and a little mild soap, then dry both surfaces.
- Close the door slowly and watch whether the sweep actually touches the threshold across the width.
- If the sweep is damaged or clearly not reaching the threshold even though the door is aligned, that is your main repair path.
Next move: You have confirmed a worn seal or poor threshold contact instead of guessing. If the sweep looks good and contact is still inconsistent, move on to hinge tightening and alignment correction.
Step 4: Tighten hinge screws and correct a slight sag
A small drop at the hinges can open a noticeable draft at one bottom corner, especially on the latch side.
- Start with the top hinge on the door frame side.
- Tighten all accessible hinge screws by hand so you can feel whether they are actually grabbing.
- Replace any stripped or loose top hinge screws with properly fitting longer front door hinge screws that bite solid framing, if that repair is supported by what you found.
- Recheck the top reveal and the bottom gap after tightening.
- If the gap evens out and the draft drops, the door was sagging. If not, the sweep or threshold is still the better target.
Next move: The door sits straighter, the latch lines up better, and the bottom seal contacts more evenly. If tightening does not change the gap and the sweep still misses in spots, the threshold height or the door slab itself is the more likely issue.
Step 5: Make the repair that matches what you found
Once you know whether the problem is seal wear, threshold height, or sag, you can fix the actual source instead of layering on temporary patches.
- Replace the front door sweep if it is torn, flattened, hardened, or too short to touch the threshold evenly.
- Adjust or repair the front door threshold only if the door is aligned and the sweep is in decent shape but still cannot make contact.
- Replace worn or bent front door hinges if tightening screws does not remove play and the door keeps dropping.
- If the slab looks warped or the threshold area is rotted or shifting, stop at stabilization and plan for a carpenter or door pro to correct the opening.
- After the repair, close and latch the door and recheck for light, paper-strip resistance, and cold air movement along the bottom edge.
A good result: The draft is gone or greatly reduced, and the door closes without dragging or needing a hard slam.
If not: If air still comes through after a good sweep and alignment check, the leak may actually be around the frame or from hidden movement in the threshold area.
What to conclude: A successful fix restores even contact at the bottom without creating rubbing, binding, or latch problems.
Replacement Parts
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FAQ
Why is cold air only coming in on the latch side under my front door?
That usually points to a sagging door. The slab drops slightly and opens the bottom gap wider on the latch side. Check the top hinge screws and compare the gap at the top of the door before replacing the sweep.
Can I just add thicker weatherstripping under the front door?
Only if the existing front door sweep is the real problem. If the threshold is too low or the door is hanging crooked, a thicker seal can make the door drag and still not fix the leak evenly.
Should a front door sweep press hard against the threshold?
No. It should make light, even contact. Too little contact leaks air. Too much contact makes the door hard to close and wears the sweep out faster.
Why did the draft start after new flooring or threshold work?
The bottom relationship changed. The threshold may now sit lower than the sweep can reach, or the door may have been rehung slightly differently. Check contact with the door nearly closed and look for an even miss across the width.
Is a draft under the front door ever a sign of a bigger problem?
Yes. If the threshold is loose, the wood is soft, or the frame is shifting, the draft may be a symptom of rot or movement in the opening. At that point, sealing parts alone will not hold up.