Window Leaks When It Rains?
By clicking the “Submit” button, you consent to the processing of personal data. Your information is confidential, secured and will not be shared with third parties
Leaking Windows During Heavy Rain?
If your windows leaked during Ottawa’s recent heavy rainfall, you’re not alone.
Every major storm brings calls from homeowners dealing with water entering around windows, wet drywall, damp carpets, or even basement flooding.
Many people assume the rain was simply “too heavy.”
In reality, heavy rain alone rarely causes window leaks.
The real culprit is often wind-driven rain – when strong winds force water against your windows with enough pressure to expose weaknesses in aging windows, worn seals, or poor installation.
The good news? Modern windows are specifically engineered and laboratory tested to withstand these conditions.
Why Do Windows Leak When It Rains?
Water can enter around a window for several reasons.
Some are easy to fix.
Others indicate it’s time to replace the window.
Common causes include:
✔ Aging weatherstripping
✔ Failed window seals
✔ Poor original installation
✔ Builder-grade windows with lower water resistance
✔ Frame movement over time
✔ Flashing or drainage problems
✔ Years of exposure to Ottawa’s freeze-thaw cycles
If your windows leak during every major storm, the issue usually won’t solve itself.
Window Leaking From the Top?
Many homeowners immediately assume:
“My window must be broken.”
Sometimes that’s true. Often it isn’t.
Water appearing at the top or sides of the window can indicate:
- wind-driven rain overwhelming the window
- deteriorated weather seals
- flashing issues
- installation deficiencies
- a window that no longer provides adequate water resistance
A professional inspection can identify the true cause before more extensive damage occurs.
Basement Window Leaking After Heavy Rain?
Basement windows are especially vulnerable.
Unlike upper-storey windows, they often sit below grade inside window wells where water can accumulate quickly during severe storms.
If the window cannot resist the pressure created by heavy wind-driven rain—or if drainage around the window is inadequate—water may eventually find its way inside.
Not every basement leak is caused by the window itself. Foundation drainage, grading, clogged window wells, and other factors can also contribute. But aging windows are frequently one of the weakest points in the building envelope and should always be inspected as part of the solution.
What Is Water Penetration Resistance?
This is one of the most important measurements of a window’s ability to keep water outside.
During independent laboratory testing, water is sprayed onto the window while increasing air pressure simulates strong winds.
The higher the pressure a window withstands before allowing water through, the better its water penetration performance.
The measurement is expressed in Pascals (Pa).
What Does a 720 Pa Rating Mean?
Buildmart’s premium Stage Windows have been independently tested to withstand up to 720 Pascals of wind-driven rain pressure before water penetration occurs under standardized laboratory conditions.
[Download Test Report Summary]
In simple terms…
That means the window is designed to resist very heavy, wind-driven rain—the kind of weather Ottawa homeowners occasionally experience during severe thunderstorms.
This places our windows near the highest level of residential water performance available today.
Why Do Casement & Awning Windows Perform Better?
Not all window styles perform equally.
Awning and casement windows consistently rank among the best-performing operable window styles for air and water resistance.
Why?
Because when they’re closed:
- the sash compresses tightly against the weatherstripping
- multi-point locks create even pressure around the frame
- stronger wind actually helps press the sash tighter against the seals
- fewer opportunities exist for water to work its way inside
This makes these styles especially well suited for exposed elevations and homes that experience frequent wind-driven rain.
Independently Tested Performance
Our Stage Windows aren’t simply designed for superior performance—they’ve been independently tested by UL CLEB in accordance with AAMA/WDMA/CSA (NAFS) standards.
The tested window achieved:
✔ Water Penetration Resistance: 720 Pa
✔ Positive Design Pressure: 2400 Pa
✔ Negative Design Pressure: 2400 Pa
✔ Canadian Air Infiltration Rating: A3
Independent laboratory testing provides confidence that these performance ratings are measured using recognized industry standards, not marketing claims.
Why Homeowners Choose Buildmart
At Buildmart, we believe a replacement window should do more than improve curb appeal.
It should help protect your home when the weather is at its worst.
That’s why we install premium Stage Windows featuring:
- Water penetration resistance up to 720 Pa
- Triple-glazed energy-efficient glass
- Multi-point locking hardware
- Premium weatherstripping systems
- Professional installation by experienced technicians
- Products designed specifically for Canadian weather conditions
Concerned About Water Around Your Windows?
Don’t wait until the next storm.
Book a free, no-obligation window assessment with Buildmart. We’ll inspect your existing windows, identify the likely cause of the leak, and help you understand whether repair or replacement is the right solution for your home.
✓ Free Assessment
✓ Honest Recommendations
✓ Professional Installation
✓ Serving Ottawa Since 2006
Book Your Free Consultation Today!