Simple Steps to Find and Fix the Problem Fast

A leaking window isn’t just an annoyance — it can lead to water damage, mold, and rising energy bills. If you’ve noticed water around your windows, here’s how to troubleshoot the issue before it gets worse.

Common Signs of a Window Leak

Look for these early warning signs:

💧 Water stains or bubbling paint around the window
🪟 Condensation between panes (for double-pane windows)
🪣 Water pooling on the sill or floor
🧼 Musty smells or signs of mold

Possible Causes of the Leak

Most window leaks stem from one of the following:

🔧 **Poor installation** – gaps, improper flashing, or no sealing
🪟 **Damaged caulking or seals** – especially around the frame
🌧️ **Clogged weep holes** – windows are designed to drain, but debris can block them
🧱 **Cracked exterior siding or stucco** – water can sneak in behind the wall

Step-by-Step Troubleshooting

1. 🌧️ **Test with a hose** – Spray water on the window exterior to identify the leak source.
2. 🕵️ **Inspect the caulking** – Check for cracks or gaps around the window frame.
3. 🧽 **Clean weep holes** – Use a small wire or toothpick to clear out drainage holes.
4. 🔍 **Check flashing** – If water is leaking from above the frame, faulty flashing may be to blame.
5. 🏠 **Inspect walls** – Make sure the leak isn’t actually coming from the roof or another source above.

When to Call a Professional

If you’ve ruled out simple fixes, or if your window is more than 10 years old, it may be time to consider replacement. A professional can determine whether it’s a fixable issue or if new energy-efficient windows would offer a better long-term solution.

Not sure where the leak is coming from?

Request a free inspection from our window experts

Serving Niagara Falls, St. Catharines, Welland, Thorold, Fort Erie, Port Colborne, Grimsby, Beamsville, Hamilton, Ancaster, Burlington, and surrounding areas.