We are called out to houses under ten years old more often than people expect, and it is nearly always the same three details. None of them are the homeowner’s fault, and most are still worth fixing long after the warranty has lapsed.
1. No head flashing above the window
This is the big one. The window gets installed, the cladding goes on around it, and the piece of flashing that should sit above the head – lapped behind the housewrap and over the window – never goes in. On a sheltered elevation you may never know. On a wall that catches wind-driven rain, water tracks in behind the trim and runs down inside the wall assembly.
The tell is staining on the drywall below the window after heavy rain from one particular direction, with no visible leak anywhere else. We found exactly this on a porch in High River: the roof was fine, the developer had left gaps around the window head with no flashing tape behind the cladding.
2. Sealing the wrong gap
A window should drain. The perimeter is sealed on the outside at the sides and head, and deliberately left open at the bottom so anything that gets in can get back out. A common defect is a continuous bead of caulk right around the frame including the sill – which turns the opening into a bathtub.
If your window is sealed all the way round, that is not thoroughness. That is a trap.
3. Shimming in the wrong places
Shims belong at the fixing points, where they transfer load into the framing. Shimmed continuously along the jamb, or packed tight under the middle of the sill, the frame bows very slightly – not enough to see, but enough that the sash no longer meets the weatherstrip evenly. That is the draft you can feel with your hand in January on a window that is only eight years old.
Is it worth fixing after the warranty?
Usually, yes – and usually for less than people fear, because the window itself is fine. Head flashing retrofitted from the outside is a half-day job on most homes. Re-sealing correctly and re-shimming a sash is an hour. Compare that to a wall assembly that has been wet for five winters.
If you have staining, a draft, or you simply want to know whether the detail is there, send us a photo of the window from the outside and we will tell you what we can see.
