Air-Sealing an Electrical Box
We are building a high performance house in Des Moines, IA (climate zone 5), and are doing final electrical trim out. We have a fairly tight house at 1.08 ACH/50 before drywall went up, using Zip as our primary air barrier along with Aerobarrier. House has been sided and painted.
We have 4 exterior outlets going in, and currently plan to use a flush mount weathertight in use box, similar to the Arlington In-box (http://www.aifittings.com/landing/weatherproof/). I’ve talked with the electrician about how we might air seal this. My current plan is this:
– Zip tape around the back of the box to seal off all the unused punch outs.
– Sealant around the wire that will run through punch out.
– Sealant between the box and the siding/sheathing
– Weatherproof seal (some kind of putty) behind the trim plate
I’m curious if others have a tried and true method for sealing these kinds of boxes? We don’t have access to the inside of the wall any more, so everything needs to be done from the outside.
The alternative is to just use a surface mount box, which isn’t as nice looking, but also doesn’t require a hole in the exterior of the envelope.
Any suggestions? Our current air leakage, which was measure post Aerobarrier, was around 79 sq/in. So installing 4 of these boxes in a poor fashion could almost double that number.
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