07/26/2026
Case Study: Window Well Drainage and Foundation Waterproofing
A recent client came to us with water pooling in her window wells during heavy rain. The water was rising high enough to submerge the windows themselves, and it was finding its way in around the bottom of the window frame, running down the interior foundation wall.
Diagnosis
We identified two separate problems working together:
The window well was not draining. Water had nowhere to go, so it pooled and rose.
The window perimeter was not properly sealed with blue skin membrane, so once water reached the bottom of the frame, it had a path inside.
What we found after the first repair
We corrected the drainage so the window wells no longer held water. That solved the original complaint. But it also changed how water moved through the soil around the foundation. With Edmonton's recent heavy rainfall, the water that used to sit in the window well was now draining straight down to the base of the foundation wall. That concentrated flow found a different weak point: the cold joint where the foundation wall meets the footing and the interior slab. Water began coming up through that joint instead.
We had to go back and excavate the same section a second time to waterproof it properly. That is the outcome we now build our process around avoiding.
Our comprehensive approach
Fixing drainage without also waterproofing the wall below it can move the problem rather than solve it. Because of this, we now treat window well repairs as a single, complete scope rather than a series of fixes:
Excavate the full window well and backfill with wash rock instead of compacted soil or clay, so water moves through instead of collecting.
Confirm a 4-inch PVC vertical riser is in place and connected to the weeping tile.
Remove parging as needed to inspect the blue skin at the base of the window frame, and install our own sill flashing to seal that joint.
Apply a waterproofing membrane down the full excavated section to the footing, sealing the cold joint and any minor cracks in the same pass.
This addresses the drainage issue, the window seal, and the foundation wall as one system, rather than fixing one point and finding
