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It happens every year. The seasons change, and the wet weather arrives. Welcome to life in the Pacific Northwest. It is the price we pay for our green landscapes and amazing forests. With the moist climate comes leaking windows. Here are some tips you can use to determine if you can repair this issue, or you would be better served to have replacement windows installed.

This Industry Tip Will Help You More Than Any Other Information:

This is the key information that most companies don’t want to let you in on. Over 95% of all window leaks are due to improper installation. That’s right! In only a small fraction of cases is there actually an issue with your window. In most cases, windows are not installed to industry standards or best practices. In most regions, it isn’t an issue. But here in the pacific northwest, where our homes are bombarded by moisture for six to seven months a year, proper installation is critical.

At SFW Construction We Do It Right The First Time!

At SFW Construction we have seen the aftermath and adverse effects of windows being improperly installed. We train our employees to install windows, so they never leak. Before they ever install for one of our valued clients, we put them through a rigorous training program. Below is a video that shows one of our training processes.

What Windows Are The Most Likely To Leak?

Why are my windows leaking is one of the more popular questions we get asked, but what windows are most likely to leak? The most common leaking windows are in old and aging homes. However, it is not uncommon to discover leaks in newer homes, especially in wet climates. There are three main factors that cause windows to leak. The most common is poor installation. Followed by a lack of maintenance and then design challenges.


  • Installer used inferior house wrap (WRB)
  • Failure to caulk window flange during installation
  • Improperly installed or missing SAM (self-adhesive membrane)
  • Improperly installed or missing flexible pan flashing
  • Failure to integrate the above products correctly or reverse lapping
  • Missing or improper metal head flashing

Design Challenges:

  • Minimal or no overhangs to protect windows
  • Windows that sit right on rooflines
  • Windows that are directly under gutter terminations
  • Windows that are clustered and grouped together
  • Arched top windows


  • Cleaning out weep holes so windows can drain
  • Replacing missing or cracked glazing
  • Cleaning out gutters above windows
  • Ensuring window trim caulking is in good condition