Short Answer
Potential causes include improper flashing, missing flashing, failed sealants, improper integration with the weather-resistive barrier, damaged siding, and window installation problems.
Detailed Explanation
Windows are large openings in the wall assembly, and they're where siding, house wrap, and window flashing all need to integrate properly. If any of these components is missing, improperly installed, or deteriorated, water can enter at the window opening. Common problems include: flashing that's installed in the wrong order (not lapped properly to shed water), missing sill flashing (the most critical flashing point at a window), sealant that has failed with age, house wrap that's not properly integrated with the window flashing, or siding that's installed too tight against the window frame without proper clearance for drainage. Diagnosing a window-area leak requires evaluating all of these components.
Why It Matters
Window-area leaks are common but often misdiagnosed as window failure when the actual problem is flashing or integration with the wall assembly.
Common Mistakes
- ✕Assuming a window leak means the window is defective
- ✕Not evaluating flashing and house wrap integration
- ✕Missing sill flashing at the bottom of the window
Questions to Ask Your Contractor
- ?Is the flashing properly installed around the window?
- ?Is the house wrap integrated with the window flashing?
- ?Is there proper drainage behind the siding at the window?
- ?Has the sealant been checked for failure?