Certified Building Contractor CBC1265305 · Certified Roofing Contractor CCC1334811
Why does water come in under my sliding door during heavy rain?
A straight answer from a Florida state-certified contractor — then what you can check yourself and when to call. Free estimate: (954) 620-7812.
Water usually gets under a sliding door because the track can no longer drain, or because the seals and sealant around the sill have worn out. Sliding door tracks are built to catch some rain and shed it outside through small drain slots (weep holes). When those slots clog, or when wind-driven rain pushes past worn weatherstripping, the water spills over the inside lip of the sill.
The nuance is that the water you see at the floor is not always coming from the track. It can run down from a failed seal at the top or side of the frame, or from missing or damaged flashing under the sill. A simple cleaning fixes the first cause. The second needs the door opened up.
Why it happens
Florida's daily summer storms and hurricane-season rain can push water sideways against a door, not just down onto it. A track full of leaves, grit, pollen or dried debris can't drain that water fast enough, so it rises and crosses the sill. Salt air near the coast adds corrosion to rollers and tracks, and that can leave the panel sitting out of true with gaps along the bottom.
Seals age too. Weatherstripping and the bottom seal harden and flatten under UV and heat. Sealant at the sill ends and corners cracks as the frame moves. If the patio slab or threshold area slopes toward the door, water pools against it and gets pushed in more easily.
The more serious cause is hidden. If the sill pan or flashing under the door was never installed well or has failed, water can get into the wall or subfloor even when the track looks clean. Over time, that moisture can lead to soft flooring, rot in wood framing, and mildew.
What you can check yourself
Clean the track and weep holes
Vacuum out debris and wipe the track with a soft brush and rag. Gently clear the drain slots at the outer edge of the sill, taking care not to damage the seals.
Run a hose test
With a helper inside, wet the door in sections with a gentle spray, starting low and working up. Where water shows up first tells you whether it is the track, the sill ends or the frame above.
Inspect the seals
Look for weatherstripping that is flattened, cracked, brittle or pulling away. Check that the panel meets the frame evenly when closed.
Look at the outside
Check for cracked sealant at the sill ends and for water pooling on the slab or deck near the threshold.
Check the floor
Press on the flooring near the door and look for staining, swelling, a musty smell or a soft spot. Those point to water that has been getting in for a while.
When to call a pro
Call us if water still gets in after the track is clean, if the floor or trim beside the door is stained or soft, if the door is hard to roll or won't lock, or if you suspect the sill flashing has failed. We would also look at it if you're weighing repair against replacement. We're a Florida Certified Building Contractor (CBC1265305), and our certification is valid in every county in the state. We give a free estimate and a written scope before work starts.
Repairs like new rollers, weatherstripping or sealant are usually handled without a permit, but check with your local building department. Replacing the slider is different. That typically needs a permit, in-progress inspections where the code requires them, a final inspection, and then the permit closed out. We pull the permit under our own certification when the work needs one. In Miami-Dade and Broward counties (the High-Velocity Hurricane Zone), the new door needs a Miami-Dade Notice of Acceptance (NOA). Elsewhere in Florida it needs Florida Product Approval. Unpermitted or open permits can surface at sale, refinance or insurance renewal, and code enforcement may cite them. If you live in a condo or HOA community, ask about association approval before ordering.
What a pro will do
- Find the actual sourceWe test the door section by section to see whether the water comes from the track, the seals, the frame or the sill.
- Repair track and rollersCorroded or worn rollers and damaged tracks are replaced or adjusted so the panel sits level and closes tight.
- Replace weatherstripping and resealFailed seals and cracked sealant are renewed so wind-driven rain has no path in.
- Replace glass or the whole sliderIf the glass or frame is damaged, we can replace the glass. If the unit is past repair, we replace it with an impact-rated slider, with the permit and product approval that go with it.
- Open up damaged areasIf moisture has reached the sill area or subfloor, we find out what is affected and include it in the written scope before work begins.
Related questions
- Can I just caulk the bottom of the door to stop the leak?
- Caulk at the wrong place can trap water or block the weep holes, which makes things worse. Sealant belongs at the sill ends and frame joints, not across the drain path of the track.
- Do the drain holes on the outside of the sill need to stay open?
- Yes. They are how the track sheds the rain that gets in. Keep them clear of debris and don't seal them.
- Does replacing a sliding glass door need a permit?
- Replacing the door typically does, though details vary by city and county, so confirm with your local building department. The replacement also needs product approval: a Miami-Dade NOA in Miami-Dade and Broward, Florida Product Approval elsewhere.
- Can a leaking slider cause mold or rot?
- Repeated moisture at the sill can lead to damp flooring, mildew and rot in wood framing or trim near the door. Catching the source early helps keep the repair small.
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