I are actually working with rigid breadboard model expanded polystyrene while in the rim joists and imagined the same may be place underneath the sheathing between the rafter bays, and with any gaps sealed by using a urethane spray foam like Fill and Seal. Is there an outstanding that makes spray foam appropriate and rigid foam unacceptable?
We had a Zip Roof put in and a metal Roof put above it. The roof assembly will not be vented and taped all within the soffits. Ideally I might love to pack the whole cavity with blown cellulose. This string of conversations is offering me pause for believed.
If you choose not to increase the rigid foam around the portions of your roof that have a standard vented attic, your builder (or an architect) can think of a trim element that you choose to could possibly Reside with.
A. To make the most of the insulating value of the rigid foam in excess of the attic, you unquestionably want to seal up any attic vents, therefore you certainly don't need to produce a ridge vent.
Q. "I am questioning if I should furr out the rafters to have the specified thickness of spray foam, or if putting in a number of inches of polyiso foam into the underside of your rafters, once the spray foam, could perform?"
I've a 50 calendar year-aged seasonal cottage in a northern local weather. The simple 6/12 gable roof is composed of actual 2x6 rafters (24" oc), sheathed with one/two" plywood and covered with asphalt shingles. There isn't a insulation from the ceiling and I think minimal to no successful insulation inside the 2x4 walls. In the summer the warmth gain inside helps make residing Nearly unbearable. I believe that the biggest bang to the buck would be to handle the ceiling insulation challenge initially, but would like to retain the interior overall look.
Is it costlier or inexpensive to live in One more metropolis as compared to mine? Am i able to assume to invest roughly on housing or transportation prices? How do they Review with the countrywide average?
My being familiar with as I look at this blog site is usually that I don't have to bother with developing an air channel above the sheathed portion as a result of rigid foam.
As creating scientist Invoice Rose has shown, code prerequisites for roof venting ended up in no way dependant on analysis or scientific concepts. Inside of a nicely documented JLC
With my home the middle section (20ft) is vaulted, a 3x12 slope and has 8 recessed lights throughout. I've experienced leaks in several spots in this portion of the house, the leaks transpire With all the thaw and refreezing. It got The purpose previous calendar year where by I needed to shovel the complete roof immediately after Just about every snow tumble.
We really You should not know if these roofs have suitable vent channels, or what sort of vent baffles (if any) had been applied to take care of the air flow gap involving the best of your fiberglass insulation and also the underside of the roof sheathing.
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As I explained from the report look here on this page, You can not use fluffy (air-permeable) insulation within an unvented roof assembly Unless of course you consist of rigid foam or spray foam previously mentioned the fluffy insulation.
Having said that, I feel you happen to be Incorrect regarding your asphalt felt; I doubt When the felt is impermeable to water vapor. Most forms of asphalt felt are relatively permeable -- ordinarily 5 perms when dry and nearly sixty perms when damp.