Direct answer: If rain is getting in at the threshold, the usual cause is a failed bottom seal, a threshold that is set too low, or a door slab that is slightly out of alignment so the bottom edge never compresses the seal. Start by finding whether water is coming under the door, around the corners, or down the face of the door and pooling at the sill.
Most likely: Most often, the fix is a new exterior door sweep or an adjustment to the threshold so the door seals evenly across the bottom.
A little water at the inside edge can come from two very different problems: the door is not sealing, or water is being dumped onto the threshold faster than it can shed. Separate those early and you save a lot of wasted work. Reality check: even a good exterior door can leak if wind-driven rain is hitting a worn bottom seal. Common wrong move: replacing weatherstripping on the jamb when the real gap is at the bottom edge of the door.
Don’t start with: Do not start by smearing caulk across the threshold or the inside edge of the sill. That often traps water, hides the real path, and still leaves the door leaking in the next storm.
The floor gets wet just inside the middle of the door, while the corners stay mostly dry.
Start here: Start with the door bottom seal and threshold height. That pattern usually means the sweep is worn, flattened, or not touching evenly.
You see a wet spot at the latch-side or hinge-side corner after rain, sometimes with a visible daylight gap.
Start here: Check door alignment, loose hinges, and whether the slab is racked so one corner lifts off the threshold.
Rain streaks down the inside face or collects at the sill after wind-driven storms.
Start here: Look for water getting past the bottom corners, side weatherstripping, or a door that is not pulling tight against the frame.
Normal rain is fine, but a hard storm or runoff across the landing pushes water inside.
Start here: Check exterior drainage and whether the threshold is being overwhelmed, then confirm the bottom seal is still doing its job.
This is the most common reason water gets under the door. The rubber or vinyl edge hardens, tears, shrinks, or stops touching the threshold evenly.
Quick check: Close the door on a dry day and look from outside at the bottom edge. If you can see a gap, daylight, or a flattened seal, the sweep is suspect.
If the threshold is adjustable or has a compressible cap, it can sit low enough that the door never seals across the bottom.
Quick check: Run a strip of paper across several spots at the bottom with the door closed. If it slides out easily in the middle or at one corner, the threshold contact is weak there.
A sagging or slightly twisted door often leaks at one bottom corner first. The latch may still work, but the bottom edge no longer lands square on the threshold.
Quick check: Check the reveal around the door. If the top gap is uneven or the latch side looks lower at the bottom, alignment is likely part of the problem.
If the stoop pitches toward the door, gutters dump nearby, or wind pushes water hard at the opening, even a decent seal can be overwhelmed.
Quick check: Watch the exterior during rain or hose testing. If water ponds at the sill or runs directly toward the threshold, the source path needs attention too.
You need to know whether the leak is under the door, around a bottom corner, or running down from above. Those look similar from inside but lead to different fixes.
Next move: You now know whether to focus on the bottom seal, alignment at one corner, or exterior water flow. If you cannot reproduce the leak, look for staining, dirt tracks, or water marks on the threshold and lower weatherstripping to show the usual path.
What to conclude: A center leak points to the sweep or threshold contact. A one-corner leak points to alignment or a corner seal gap. Water appearing higher up suggests the threshold is not the first failure point.
This is the safest and most common fix, and you can usually confirm it with a close visual check before buying anything.
Next move: If the seal is clearly damaged or no longer touches the threshold, replacing the exterior door sweep is the right next move. If the sweep looks intact and contact is still weak, move to threshold adjustment and door alignment.
What to conclude: A visibly worn or uneven bottom seal is a direct cause, not a guess. If the seal looks good but does not compress, the door or threshold position is usually the real issue.
A threshold that is too low leaves a leak path even with a decent sweep. This is especially common when the middle leaks more than the corners.
Next move: If the paper drag becomes even and the leak stops, the threshold was simply too low or unevenly set. If one side still has weak contact, the door slab is likely out of alignment rather than the threshold being the only problem.
When one corner leaks, the door usually is not landing square on the threshold. Small alignment issues show up at the bottom first.
Next move: If tightening hinges evens the reveal and improves bottom contact, test again in rain before replacing parts. If the door still leaks at one corner, the likely repair is a new exterior door sweep plus hinge correction, or a pro adjustment if the frame has moved.
Once the leak path is clear, the right fix is usually straightforward. The key is not mixing a sealing problem with a drainage problem.
A good result: The threshold stays dry inside during the next storm, and the door closes without dragging or needing a hard slam.
If not: If a new sweep and proper threshold contact still do not stop the leak, the problem is likely frame, sill pan, or exterior water management rather than a simple door-bottom part.
What to conclude: A confirmed failed seal supports a part replacement. A leak that survives those fixes points to the opening itself, not just the door bottom.
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That usually means the seal is marginal rather than completely gone. Wind pushes water harder at the bottom corners and can force it past a worn sweep or a small alignment gap that stays dry in lighter rain.
Usually no. Caulk can hide the path for a while, but it does not fix a bad bottom seal or a door that is not closing square. It can also trap water where it should drain away.
If the sweep is torn, stiff, or not touching the threshold, start there. If the sweep looks good but the threshold insert is crushed flat or the adjustable threshold sits too low, the threshold side is more likely.
Yes. A small sag at the top hinge can lift one bottom corner just enough to break the seal. You may not notice much else besides a corner leak or a latch that feels slightly off.
Then the problem is probably not just the sweep. Recheck threshold height, corner alignment, and whether water is pooling outside the door. If those look wrong, the opening or exterior drainage needs repair.