GP forcefield and rigid foam
I’m working on a project house of mine and wanted to try and experiment with some of the newer sheathing with integrated wrb for various reasons but I’ve run into what seems like a problem to me. I used the Georgia pacific forcefield on the walls and taped all the seams, but I want to use rigid foam on the entire exterior to reduce thermal bridging. My preference would be to then cover the foam with a house wrap to help keep the foam from deteriorating due to sunlight as my doors are still 3 months out. It seems like with this wall system there is the possibility of moisture getting trapped between the foam and the sheathing causing damage long term. I guess my questions are 1. Should I be taping the foam seems. 2 should I put the house wrap on the exterior of the foam
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Replies
Watch out for some house wraps having an exposure statement and the instructions call for much sooner. I noticed that on one I used.
Lot of this depends on where your window are mounted. Since you already have the sheathing with taped seams as the main air barrier, extra taping is not adding anything and in some ways makes it works as it limits diffusion drying between the WRB and the foam.
If your windows are at the sheathing, simplest is to install the rigid and call it a day. No need for a 2nd layer of house wrap or taping. Rigid holds up pretty well to UV exposure, 3 months is not a long time.
If your windows are outies with the flange at the same plane as the rigid, I would add a house wrap over the foam. This means all your WRB details are standard construction since everything is in plane and you don't have to do flashing tape origami around the window bucks. Again, no point in taping the rigid.
PS. The outies on mini bucks with the WRB over the foam is my proffered assembly with exterior rigid. Keeps everything nice and simple and including the exterior trim around the windows.