Unvented roof – I know. So wrong, but…
I’m building a tiny house on wheels with a simple shed roof. I have 2×6 rafters and am insulating with two layers of 2″ XPS which are carefully fitted, spray foamed (foam in a can) around joints and edges, then, once the spray foam has been trimmed level with the XPS, sealed with R-Guard Air Dam. Each of the two layers are treated like this, and the joints are offset. A third 1″ XPS layer is added and treated the same way, and a final 1″ XPS layer is then fitted to cover the ceiling crosswise to the rafters and routered out for the portion of the rafters which protrude from the nominally 5″ thick XPS sandwich. Thus, when seen from below, the insulated ceiling shows no rafters, only the blue of the final layer, with joints again sealed with R-Guard Air Dam.
Yes. A fortune in sealant, a lot of time and effort, and Bubba ain’t helping, but I hope this works to keep condensate from forming.
Comments please. Too much? Not enough?
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