A homeowner contacted The Roof Whisperer after noticing a leak on the ceiling below a bay window. To identify the root cause, we recommended performing a professional water test (learn more about our service charges in the FAQs).

We arrived early on a cold morning and quickly observed dripping water from the edge of the copper roof. At first glance, it appeared to be condensation forming between the metal panels and the roof deck of the bay window. However, after completing the water test, we discovered the actual leak source was the window sill above the copper bay roof.

Our Repair Process

To address both the leak and condensation issues, we proposed carefully removing the copper roof panels and underlying plywood to expose the problem area. Once open, we confirmed that:

• The copper roof was installed directly over wood with no underlayment, allowing moisture buildup.

• Air leakage from inside the home contributed to condensation under the copper panels.

Our repair steps included:

1. Sealing the window sill to stop the major water infiltration.

2. Applying 2 lb spray foam insulation between the drywall and bay window roof. This provided both insulation and a vapour barrier to prevent future condensation.

3. Replacing all compromised plywood sheathing damaged by leaks and moisture.

4. Reinstalling every copper panel with precision for long-lasting protection.

5. Cutting a reglet into the mortar joints to install new counter flashing properly.

6. Sealing all connections with Dymonic 100 caulking where the metal roof met the stone wall and mortar joints.

The Result

This project restored the integrity of the bay window copper roof and eliminated both the leak and condensation issues. With proper flashing, underlayment, insulation, and vapour protection now in place, the homeowner can enjoy peace of mind knowing their copper roof system is watertight and built to last.

If you’re experiencing bay window leaks, copper roof issues, or condensation problems in your home, trust the experts at The Roof Whisperer for accurate diagnosis and long-term solutions.