Water Leaking Around My Window — Causes and What to Do

Water around your windows isn't just a cosmetic problem — it can cause mold, rot, and structural damage if not addressed quickly. Here's what to do right now and what's likely causing it.

Immediate Steps

1. Place towels to absorb water and protect your flooring
2. Take photos for documentation (especially if storm-related — you may need these for insurance)
3. Check if the leak is coming from ABOVE the window (roof/flashing issue) or FROM the window itself (seal/frame issue)
4. If it's actively raining, don't attempt exterior repairs — wait for dry weather

Common Causes

Failed Exterior Caulk

The caulk seal between your window frame and siding deteriorates over time from UV and temperature cycling. Once it cracks or separates, water runs behind the siding and into the wall cavity, eventually appearing around the interior window trim. Re-caulking can work as a temporary fix if the window and frame are otherwise sound.

Flashing Failure

Proper window flashing (metal or membrane material that directs water away from the frame) is the most critical waterproofing detail in window installation. If the original installation skipped proper flashing or if it has corroded/failed over time, water finds its way behind the window. This usually requires window removal and reinstallation with proper flashing to fix permanently.

Frame Rot

Wood window frames in Illinois eventually succumb to moisture. Once rot begins, the frame loses its ability to seal against the wall opening. If you see soft spots, discoloration, or can push a screwdriver into the frame easily, the frame is rotted and the window needs full replacement.

When to Call a Professional

If the leak is persistent, if you see mold or discoloration on the wall around the window, or if the frame feels soft — call us for a free assessment. Water damage behind walls gets worse quickly and can turn a window replacement into a major repair if ignored. Schedule your free assessment →