A squall line crosses Delray Beach on a July afternoon, and for twenty minutes the rain blows in sideways off the ocean. The next morning there is a damp patch on the carpet in front of the sliding glass door. A week later, the paint under one corner of the bedroom window starts to bubble.
Window and sliding door leaks are a common way rain gets into South Florida walls, and much of that water never shows on the surface. It runs down inside the wall and soaks the bottom of the drywall, the baseboard, and the floor. This article explains how wind-driven rain gets past windows and sliders, the signs to watch for, how a contractor finds the entry point, and why the wall itself usually needs moisture mapping and drying.
Why wind-driven rain finds windows and sliders
Ordinary rain falls mostly downward and runs off the house. Rain in a summer thunderstorm or a tropical system is driven sideways, and the wind presses it against the face of the building. That pressure forces water into gaps that stay dry in a light shower: the joint between a window frame and the stucco, the corners of a door frame, a hairline crack in the wall. It can also push water up and over the inside edge of a sliding door track.
Windows and doors are holes cut through the wall, and every hole has seams. South Florida’s rainy season runs roughly from mid-May to mid-October, and hurricane season runs from June 1 to November 30, so those seams get tested again and again for half the year. A gap that lets in a little water per storm can, over a season, keep a wall cavity wet.
How window and sliding door leaks start
Failed perimeter caulk and sealant
The sealant joint between the window or door frame and the wall is the first line of defense. Sun, heat, and movement break it down over time. It shrinks, cracks, or pulls away from one side. A gap you can slide a fingernail into is enough for wind-driven rain.
Clogged weep holes and dirty sliding door tracks
Sliding door tracks and many window frames are designed to collect some water and drain it back outside through small openings called weep holes. Sand, leaves, dead insects, and dirt pack into the track and plug those holes. During a storm the track fills, and once the water rises above the inside edge, it spills onto the floor. A slider that leaks only in heavy rain often has nothing worse than a dirty track.
Missing or failed flashing
Flashing is the membrane or metal that directs water around a window opening and back out of the wall. If it was left out, lapped in the wrong order, or damaged when a window was replaced, water that gets behind the frame has nowhere to go but into the wall. Flashing problems are hard to see without taking something apart, which is why they often turn up during a water test.
Stucco cracks around openings
Many South Florida homes are concrete block with a stucco finish. Stucco tends to crack at the corners of windows and doors, where stress concentrates, and those cracks often run diagonally from the corner. Water enters the crack, gets behind the stucco, and follows the block down to the bottom of the opening. Block is porous, so a wall that stays wet can pass moisture inward over time.
Worn weatherstripping and seals
Worn weatherstripping on sliders and failed seals around the glass can let water in through the unit itself, especially on older doors and windows that have been through many storm seasons.
Signs water is getting in around a window or slider
- Stains below window corners, often a narrow brown or yellow mark running down from one lower corner
- Soft or swollen sills. Wood and MDF sills and trim swell and darken when water gets under them.
- Peeling or bubbling paint on the wall below a window, on the window return, or along the baseboard
- Rusty tack strip or stained carpet near a slider. Pull back a corner of the carpet. The tack strip underneath should be clean and dry, not rusted or dark.
- Lifting or cupped laminate or wood flooring in front of a sliding door
- Loose tile or darkened grout at the slider threshold
- A musty smell after rain, especially one that fades in dry weather and returns with the next storm
- Water still sitting in the track hours after the rain stops
Note when you see each sign and what the weather was. A leak that only shows up when the wind blows from the east, or only in heavy storms, gives a contractor a head start. For more of the quieter signs, see how to spot early signs of water leaks.
Finding the entry point: how a water test works
Water can enter at one spot and show up a few feet away, so window and door leaks are rarely traced by looking alone. The usual method is a controlled water test, done by a window and door contractor, a general contractor, or a building envelope consultant:
- The tester starts low on the opening, at the sill or the bottom of the door frame, and wets one small section at a time.
- Each section is sprayed for a set period while someone watches inside with a flashlight and a moisture meter.
- If nothing shows, the tester moves up: the lower corners, then the sides, the head of the window, and the stucco around it.
- When water appears inside, the last section sprayed is the likely entry point.
Working from the bottom up matters. Spray the top first and water runs down over everything below it, so you cannot tell which part leaked. The repair belongs to that contractor, and it might be new sealant, cleared weep holes, new flashing, a stucco repair, or a replacement unit. Edwards Property Remediation deals with what the water left behind in the wall.
Why the wall needs moisture mapping and drying
A window leak rarely stays where you can see it. In a concrete block home, the drywall on exterior walls is often attached to wood furring strips over the block, which leaves a narrow space where water can run down and sit. From there it wicks into the bottom of the drywall, soaks the back of the baseboard, and reaches the carpet pad or flooring underlayment.
From the room side, the wall may look fine or show only a small stain. Moisture mapping finds the real footprint. Meters read the drywall and trim across and below the opening, and thermal imaging shows cooler, damp areas that the meter then confirms. The result is a map of what is wet, how wet it is, and how far it extends. Our article on the science of moisture mapping explains the readings in more detail.
Mold risk inside the wall
The inside of an exterior wall is dark, has little air movement, and is lined with paper-faced drywall and wood. Once it is wet, mold can start growing within 24 to 48 hours. Because the growth is on the back of the drywall or on the furring strips, the first sign is often a musty smell rather than anything you can see. Small leaks storm after storm can be worse than one big one, because the wall never fully dries in between. That cycle is a common reason mold keeps coming back after water damage.
Fixing the window without drying the wall leaves the moisture in place. Drying the wall without fixing the window means it gets wet again in the next storm. Both have to happen.
How Edwards Property Remediation handles a window or slider leak
- Deal with standing water first. If water is on the floor now, our emergency water extraction crew removes it. We respond 24/7.
- Moisture mapping. We map the wall, sill, baseboard, and floor around and below the opening.
- Controlled removal. Where readings call for it, we remove baseboard, wet carpet pad, and a strip of lower drywall to open the cavity, keeping as much of the wall as the readings allow.
- Structural drying. Air movers and dehumidifiers dry the cavity, framing, and block to documented target readings, with moisture checks as the work progresses.
- Mold remediation if growth is found. Affected materials are removed under containment and the cavity is cleaned before anything is closed up.
- Documentation. Photos, readings, and drying records go into a file you can share with your insurer and your window contractor. Our insurance-ready documentation page explains what that file includes.
How to prevent window and sliding door leaks
- Clean sliding door tracks and weep holes several times a year, and always before the rainy season. Vacuum the track, then pour in a little water and make sure it drains to the outside. Clear weep holes gently with a pipe cleaner or thin wire. Never caulk them shut.
- Inspect caulk and sealant every year before the rainy season starts in May. Look for cracks, gaps, and sealant pulling away from the frame or the stucco. Have failed joints cut out and resealed rather than smearing new caulk over old.
- Check after every named storm. Walk the house inside and out after each tropical storm or hurricane. Look at sills, the floor in front of sliders, and the tack strip under carpet near doors.
- Get stucco cracks sealed at window and door corners before they widen.
- Keep sprinklers off windows and sliders. A sprinkler head aimed at the wall soaks the same openings several times a week.
- Ask about flashing when you replace windows or doors, and how the openings will be sealed.
Our hurricane season property checklist covers the rest of the house.
Frequently asked questions
Why does my sliding door only leak during big storms?
Wind-driven rain pushes water into the track faster and harder than ordinary rain. If the weep holes are partly clogged, the track can handle a light shower but fills and overflows in a strong storm. Cleaning the track and the weep holes is the first thing to try.
Can I just recaulk around the window myself?
Recaulking a failed exterior joint can help, but only if that joint is the actual entry point. Leaks also come through flashing, stucco cracks, and the window unit itself. If a leak keeps coming back, have a contractor water-test the opening before more sealant goes on.
How do I know if the wall behind the window is wet?
Stains, bubbling paint, swollen baseboards, and a musty smell after rain are common signs, but a wall can be wet with none of them. Moisture meters and thermal imaging show whether the drywall and baseboard are wet and how far the moisture extends.
Will mold grow inside the wall after a window leak?
It can. Mold can start growing on damp materials within 24 to 48 hours, and the inside of an exterior wall is dark with little airflow. A small one-time leak that dries quickly may not cause growth. Repeated leaks storm after storm are the bigger risk.
Does homeowners insurance cover window leak damage?
It depends on your policy and the cause. Damage from a sudden event may be treated differently from long-term seepage or wear. Photograph the damage, keep your repair records, and call your agent.
Water coming in around a window or slider in Palm Beach County
Edwards Property Remediation dries walls and floors after window and door leaks across Palm Beach County, including Delray Beach, Boca Raton, Boynton Beach, Jupiter, and West Palm Beach. If the last storm left a stain under a window, a damp carpet by the slider, or a smell that will not clear, call (754) 221-6945, email info@eprllc.net, or book an appointment online.
