Reflective Bubble wrap
I posted a question about a job that I am taking on and received good feedback a while back. I wanted to briefly revisit it in the hopes of confirming my point of view. The client is insisting that reflective bubble wrap is the answer and I am pretty sure it is not (is it ever?). Hoping to return to my discussion with him with a more complete explanation, or at least more confidence, for why it is not.
Coastal Maine, zone 6, 800 square feet, 8/12 pitch, gabled cathedral roof. The house exists and is uninsulated. We are insulating the roof and walls. At issue is the roof. From the outside it is asphalt shingles, ice and water shield, 5/8 sheathing over 2×8″ rafters. We plan on creating 1″vent channels on the underside of the sheathing by ripping 1x material and installing luan plywood (side question: this is made from birch now and no longer imported from the Phillipines, right?). We will then do 6 inches of rockwool in the bays (i know, subcode), membrain, and then shiplap. There will be a ridge vent and soffit vents.
This past summer, the sun baked on the asphalt shingles and the temperatures in the loft area were well over 100 degrees. As a fix, my client installed reflective bubble wrap (1/4″) by stapling it to the underside of the sheathing. He did this work recently so its hard to tell if it fixed anything.
I contend that because of our chosen system for ventilating and insulating the roof, the bubble wrap is now a liability because it will trap moisture and will negate the purpose of the venting. Am i correct?
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