Window Leak Investigation and Water Testing

Two different questions: product and installation

A window or door can leak through the unit itself: frame corners, glazing seals, sill weeps, or the seals at operable sashes and panels. It can also leak around the unit, where flashings, the water-resistive barrier, and sealant joints are supposed to direct water out. The repair differs depending on which path is active.

Manufactured units are rated in laboratories for water penetration resistance under defined test conditions. Installed performance then depends on the opening: sill pan flashings, flashing lap order, integration with the wall barrier, and the rough opening itself.

Doors add exposure at thresholds and tracks. Sliding and swinging doors at decks and balconies sit where water collects, so the sill pan, the threshold transition, and the deck waterproofing must work together.

How window and door water testing works

Field water testing reproduces wind-driven rain under controlled observation. A calibrated spray rack wets the exterior while, in many tests, a chamber on the interior side creates a pressure difference across the unit. Observers watch the interior and record when and where water appears.

Published standards describe these methods. ASTM E1105 covers field water penetration testing of installed windows, doors, skylights, and curtain walls under a static air pressure difference. AAMA 502 addresses field testing of newly installed windows and doors, and AAMA 501.2 describes a nozzle check for storefronts and curtain walls.

Testing in stages separates the questions. The unit may be tested with its perimeter masked, then the perimeter tested on its own, so each result points to one path. Where the parties agree, removing interior finishes lets observers see exactly where water travels.

Documenting the results

Water test results are only as useful as the record behind them. A complete record notes the units tested, their condition before testing, the test setup, pressures, water application, duration, and the time and location of any leak.

We use state-of-the-art cameras and video documentation techniques to provide trial-ready exhibits. Gregg de Haan prepares field testing data for trial, where the record has to be clear to people who were never on site.

If a unit appears to have a manufacturing defect, we are aligned with several laboratories that test and analyze product failure. Field samples are kept at our office in case they are needed at trial.

Codes, SB800, and rated performance

For many California homes, SB800 includes standards addressing water that passes beyond, around, or through windows and doors. Building codes and manufacturer instructions set the installation requirements for each opening.

We are educated on past and current building codes, SB800, and current and past building product performance testing. That background helps place a field result alongside the product’s rated performance and the requirements that applied when it was installed.

Our conceptual repair scopes and cost estimates follow the findings. Where testing separates product leaks from installation leaks, the scope can reflect that distinction, which often changes the extent and cost of the work.

Common warning signs

1. 01Stains, swelling, or peeling paint below window and door corners
2. 02Water on sills or floors after wind-driven rain
3. 03Damp or decayed framing or trim around openings
4. 04Fogging between the panes of insulated glass
5. 05Clogged, missing, or blocked weep openings
6. 06Water entering at sliding door tracks or thresholds
7. 07Cracked or separated sealant at the perimeter