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How Do I Stop Water From Seeping Under My Exterior Door?

Last updated October 31, 2026

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The short answer

Check the Gap and Weatherstripping

Start by inspecting the bottom of your door. Close it and look for daylight or feel for drafts along the bottom edge. A gap of even a quarter inch lets water push through during rain. The rubber or vinyl strip attached to the door bottom is your first defense.

Many exterior doors have an adjustable threshold. Look for screws on the top of the threshold piece. Turning them clockwise raises the threshold, which closes the gap under the door. Turn them a little at a time and test the door swing. You want a snug seal without making the door hard to open.

Fix Outside Grading and Drainage

Water often seeps under a door because it pools right in front of it. Look at the ground outside your door. The soil or concrete should slope away from your home. If it slopes toward the door, rain runs straight at the gap. Add soil or a concrete patch to create a slope of about one inch per foot for the first few feet.

If your threshold is not adjustable, you can add a new sweep or a vinyl insert that sits on top of the threshold. Some thresholds have a replaceable rubber gasket that wears out over time. Remove the old gasket and slide in a new one. This is a simple fix that often solves the seepage problem.

When Water Keeps Coming In

If you have sealed the gap and fixed the grading but water still seeps under, the problem might be deeper. A high water table or a broken underground pipe can push water up through the slab. Water can also track along the door frame from a leak higher up on the wall. Look for stains on the wall or bubbling paint near the door.

In that case, you need a professional water damage inspection. The pros can use moisture meters to find the source. They can also check if water has already damaged your subfloor or door frame. Catching it early prevents rot and mold. If you see dark spots, peeling paint, or a musty smell, do not wait.

Protecting Your Floor After a Leak

Once water gets under the door, it can soak into hardwood, laminate, or carpet. Even a small amount can cause swelling or staining. Dry the area quickly with towels and a fan. If the water sat for more than a few hours, the subfloor may be wet. You might need to remove the flooring to dry it properly.

Water damage cleanup often involves pulling up wet carpet or cutting out damaged sections of hard flooring. The pros can extract the water and set up drying equipment. They can also treat the area to prevent mold. If the leak happened during a storm, check your insurance policy. Policies vary, and your insurer decides what is covered.

Preventing Future Seepage

Make a seasonal check of your exterior doors. Before the rainy season, test each door for gaps and replace any worn seals. Clean the gutters and confirm downspouts direct water away. Trim any plants that hold moisture against the door frame. A few minutes of maintenance can save you from a costly repair later.

If you live in Fresno, pay attention to the first big storm after a long dry spell. The soil may be compacted and hard, so water runs off quickly. Check the area around your door during that first rain. If you see puddles forming, fix the slope before the next storm. Keep a mop and towels handy just in case.

You can handle most door sealing work yourself. But if water has already damaged your floor, walls, or door frame, you need professional help. Water damage repair services can assess the extent of the damage and dry the structure properly. They can also identify hidden water that you cannot see. Do not ignore a recurring leak under your door. Water that seeps in repeatedly can weaken the structure and encourage mold growth. Call for a water damage inspection if you see any signs of moisture damage. The pros can tell you what work is needed and what your options are. Acting quickly gives you the right chance to limit the damage.

Water damage does not wait

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Frequently asked questions

Can I just use caulk to seal under the door?

Caulk is not the right fix for a door bottom. It will crack and peel as the door moves and flexes. Use a door sweep or weatherstripping instead. Those materials are designed to compress and seal while still allowing the door to open and close normally.

How much gap is too much under an exterior door?

A gap of more than a quarter inch is too much. That gap lets water, drafts, and pests get in. You can measure it with a ruler or a piece of paper. If the paper slides under the door easily, you need a better seal.

Will a new door stop the water problem?

A new door can help if the old door is warped or rotted. But the real issue is often the threshold or the ground outside. Fix the sealing and drainage first. If the door frame is damaged, replacing the door may be necessary, but inspect the cause first.

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