Replies

1. 
   plumb_bob | Jun 20, 2022 06:06pm | #1

   Not sure where you are, but up in cold country we take the insulating and sealing of the gap between framing and window very seriously. If not, there would be terrible cold drafts, which would lead to condensation, which leads to water.
   In the old days the gap was stuffed with fiber glass insulation, which performed poorly. Now CCSF is the most common application, and this works well unless there is substantial movement of the frame, which will crack the foam and lead to air leaks (I have heard this is true but have never seen a bad example).
   Some of the best building science guys out of Vancouver now recommend backing rod and caulk.

1. 
   sunrisehomestead | Jun 20, 2022 06:36pm | #2

   I'm in northern california, coastal. My understanding from passive house training is spray foam is not to be relied on for air sealing and either a backer rod + caulk form of air seal or tape should be used on the interior to seal the jamb to the framing or air barrier.

   I've heard alot of folks talk against using spray foam in this cavity but haven't found any next level solution that seems educated and building science savvy.

2. Expert Member
   MALCOLM TAYLOR | Jun 20, 2022 07:15pm | #3

   sunrisehomestead,

   I think this will answer your questions:
   https://www.greenbuildingadvisor.com/article/the-bs-beer-show-windows-part-ii-installation-details

   In the BS & Beer episode her comments start around the 18th minute.

   Christine is fine with some insulation, as long as you leave the outer portion of the gap empty as a drainage plane, and to equalize pressure.

1. 
   sunrisehomestead | Jun 20, 2022 07:51pm | #4

   GOT IT! this is super helpful I will take a look

   Thanks
   Nick

2. 
   sunrisehomestead | Jun 20, 2022 08:01pm | #5

   I actually don't see her commenting at 18 minutes. Might have to watch the whole video...unless theres a chance this is the wrong video?

   Thanks!
   Nick