How We Fixed a Poorly Built Pergola That Was Causing Water Damage to the House

When a pergola is installed against the wall of a house, it’s critical to make sure the connection between the two roofs is completely sealed. Unfortunately, that wasn’t the case for one of our recent clients.

ALUMINUMOUTDOOR WORKOUR WORKSROOFDECKS, PERGOLAS & GAZEBOS

7/12/20251 min read

The original builders of this pergola left a significant gap between the house’s shingle roof and the newly installed corrugated metal roof of the pergola. As a result, every time it rained, water would flow directly into the gap and run down the side of the house. Over time, this kind of water exposure can damage stucco, cause wood rot behind the siding, and even lead to mold problems inside the wall structure.

Our Solution: Custom Flashing Installation

We were called in to evaluate and fix the problem. Our first step was to inspect the connection and confirm the root cause: the lack of flashing and proper water redirection.

Here's how we addressed it:

Measured and cut custom flashing to fit snugly under the shingles of the existing roof and extend over the top of the corrugated pergola panels.
Lifted shingles carefully to slide the new metal flashing underneath without damaging the roofing system.
Secured the flashing with roofing screws and applied roofing sealant to prevent leaks.
Tested the water flow to ensure that any rainwater coming off the main roof would now run safely onto the pergola roof and away from the house wall.

We also resealed and reinforced the edges to ensure long-term durability.

Why Proper Flashing Matters

Flashing isn’t just an accessory — it’s a crucial part of any roof transition. Without it, water will find its way into cracks and gaps, often without being noticed until the damage is extensive. In this case, the oversight of not installing flashing at the roof-to-wall junction almost led to serious water damage for the homeowner.

Final Result

Now, instead of water running down the wall, it flows smoothly from the shingle roof to the pergola roof and away from the structure — exactly as it should. The client can now enjoy their outdoor space without worrying about hidden leaks or future stucco repairs.

Need expert help fixing a roofing or water flow issue?
📞 Call or text ProHands Handyman at 818-401-7766
We’ll be happy to help you find a long-term solution.