High Urgency
Water Leaking Around Windows: Causes, Diagnosis & Repair
Water leaking around windows can cause mold, rot, and structural damage. Virginia Glass Windows helps DMV homeowners identify whether the problem is glass, frame, or siding related.
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Warning Signs
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Known Causes
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Solution Steps
Free
Professional Assessment
Common Symptoms
Water stains or drips on the interior window sill or below the window
Paint bubbling or peeling near the window frame
Mold growth on the window trim or adjacent wall
Wet insulation visible around the window rough opening
Water entry during heavy rain or wind-driven rain events
Condensation on the interior wall surface near the window
What Causes This
Failed exterior window caulk allowing water to enter behind the frame
Missing or damaged flashing above the window head
Failed or improperly installed housewrap or weather barrier at the rough opening
Cracked or broken glazing putty around single-pane glass
Failed IGU seal creating interior humidity that mimics a water leak
Improper slope of the window sill causing water to pond against the frame
How to Fix It
Solution Steps
1Determine whether the leak occurs from outside in (true infiltration) or is condensation-related
2Inspect exterior caulk at the window perimeter — re-apply where cracked, separated, or missing
3Check and repair head flashing if it is bent, corroded, or missing
4For glazing putty failures, remove loose putty, prime the rabbet, and apply new DAP glazing compound
5For persistent leaks, hire a building envelope specialist who can test windows with a hose or blower door
When to Call a Professional
Any leak accompanied by mold growth — mold remediation is a specialized service
Leaks where flashing repair requires removing exterior siding or trim
Commercial building window leaks where multiple units are affected — a systemic investigation is needed
When the source of the leak cannot be determined from visual inspection
Stay Ahead
Prevention Tips
Re-caulk all window perimeters every 5 to 7 years with exterior-grade silicone or siliconized latex
Maintain head flashings and ensure they direct water away from the window head
Keep gutters clean to prevent overflow that saturates window heads
Inspect glazing putty on older single-pane windows annually
Common Questions
FAQs About This Problem
Run a garden hose slowly over the window from bottom to top, section by section, while someone watches from inside. This systematic approach usually identifies the entry point. Start with the sill, then the sides, then the head flashing.
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