What is the best way to install windows so they don't leak air and water?
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What is the best way to do Stucco/E.I.F.S exterior window wraps?
Pat Estes
July 17, 2020Last updated: Sept. 25, 2020
Ive been a Plasterer for 30yrs and always wrapped and flashed windows to protect from water intrusion. Yet I see roofers doing it wrong, painters attempting it and the issues always effected stucco. Is there a licensed or certification for pan flashing or air barrier installation?
Installing a window properly to avoid air and water leaks is left up to the installer, there is no certification that we know of. There are different ways to install windows that work, so one would hope that a window detail would be properly drawn by a designer. We agree with you that some installation techniques are bound to fail, or simple mistakes that could have been easily avoided can lead to higher energy bills from heat loss (usually air leakage around the frames), and water infiltration and damage if there wasn’t a strategy in place to avoid standing water and repel driving rain. Here is our page on window installation with some easy to follow tips that will improve the performance and durability –
How to install windows properly
I know the page doesn’t cover stucco specifically, but window installation should direct all water to the building exterior no matter what type it is.
You will see on that page two methods of air sealing we tried and we were really happy with how little air leakage we found when we relied not on caulking but rather on a high-performance building tape.
You can either purchase a flashing pan to collect and divert water or you can build your own with the right materials like we did in the window installation video on that page.
One of the most important details that I see people struggling with is when trying to fix and flash high performance windows in a building shell with exterior insulation. Using an insulated window buck system like the one Legalett has developed is cost effective and gives an extended and insulating window reveal for securely fixing windows that makes it easier to h out and seal to prevent water ingress and condensation. A simple and cost effective solution that I recommend - and also useful for ICF construction.