Impact Windows and Sliding Doors: Leaks That Cause Hidden Mold
Impact windows and doors are one of the best upgrades a South Florida property can have. They are built to keep the glass intact when debris hits it. What they are not is a guarantee that water stays out. The glass is rarely where a leak happens. Water gets in around the unit, at the frame, the sill, the track and the joint between the window and the wall, and once it is inside the wall it can feed mold for a long time before anything shows on the paint.
Where the water actually gets in
- Perimeter sealant. The bead of caulk between the frame and the stucco does a lot of work. Sun and heat dry it out, it cracks or pulls away, and wind-driven rain is pushed straight into the gap.
- Clogged weep holes. Window frames and sliding door tracks are designed to collect some water and drain it outside through small weep holes. When those fill with dirt, sand, paint or insect nests, the track fills up and overflows to the inside.
- The opening itself. If the flashing or waterproofing around the rough opening was skipped or done poorly at installation, water that gets behind the stucco has a path into the wall. This is common with replacement units fitted into older openings.
- Sill and track problems. A sill with no slope to the exterior, a balcony surface that drains toward the door, or a track set lower than the outside finish lets water pond against the unit.
- Worn weatherstripping and rollers. A sliding door that no longer closes squarely or seals tightly leaks air and rain at the meeting edges.
- Stucco cracks at the corners. Cracks tend to radiate from window corners, and they deliver water directly to the framing of the opening.
Why it turns into hidden mold
Water that enters at a window does not stay at the window. It runs down inside the wall and collects below the sill and at the floor line. There it meets the paper back of the drywall, wood furring strips, wood window bucks, baseboards and, with sliding doors, the edge of the flooring and its underlayment. These materials can begin to grow mold within 24 to 48 hours of getting wet. Because each storm rewets the same spot, the area rarely dries completely during rainy season.
High-rise condos add another factor. Wind pressure on upper floors is stronger, and water that enters one unit can travel down the wall or across the slab into the unit below.
Signs to look for
- Stains, bubbling paint or soft drywall directly under a window sill or at the lower corners.
- Baseboards beside a sliding door that are swollen, discolored or separating.
- Flooring near the door that lifts, cups or has dark seams.
- A musty odor near a window or door that is strongest after rain.
- Water or dirt lines standing in the track well after a storm has passed.
- Rust on screws, corner bead or track hardware.
One point of confusion: water beads on the room side of the glass on a humid morning are usually condensation, not a leak. That is a humidity and airflow issue. It still matters, because condensation running down onto a sill every day can grow mold too, but the fix is different.
A yearly maintenance routine
Do this before rainy season starts, and again after any major storm.
- Vacuum the tracks, then flush them with a little water and confirm it drains out through the weep holes. Clear blocked holes gently with a small brush or a piece of wire.
- Walk the exterior and inspect the sealant around every frame. Look for gaps, cracks and sections that have pulled away.
- Check the stucco at the corners of each opening for cracks.
- Close each door and window and check that it latches firmly and the weatherstripping is intact.
- After a heavy, windy rain, feel along the sill and the floor beside sliding doors for dampness.
Recaulking and repainting are within reach for many homeowners in a single-family house. In a condo, the exterior of the windows and the building envelope are often the association's responsibility, though this varies. Check your association documents, report leaks in writing, and keep dated photos.
If water has already gotten in
Dry what you can immediately with towels, fans and a dehumidifier. If drywall or baseboard has been wet repeatedly, drying the surface is not enough, since the hidden side is usually in worse condition. Proper remediation means opening the affected section under containment, removing wet drywall, baseboard and insulation, cleaning and drying the structure, and confirming it is dry before closing it. The leak itself must be corrected by a window or waterproofing contractor, or the repair will not last.
Getting it handled
Stains below a sill or a musty smell by the slider are worth acting on before the next storm season adds to them. Request an on-site remediation estimate at drymiami.com or call (954) 778-7999. The visit is $79, credited in full toward the job if you hire DryMiami.
Mold problem at home?
We come out, find the moisture source and give you a written remediation estimate. The visit is $79, credited in full toward your job if you hire us.
