Q. "You say 'You don't want an interior vapor barrier,' but You furthermore mght express that 'you need a superior air barrier on both sides of the fiberglass batts.' The latter would transform an inside vapor barrier not so?"
We're going to give it a try. Existing can be a fourteen year outdated roof with two" of closed cell roofing foam using an acrylic elastomeric coating.
Q. "I'm wondering if I need to furr out the rafters to acquire the specified thickness of spray foam, or if installing a number of inches of polyiso foam to the underside of your rafters, after the spray foam, could do the job?"
With This technique , there isn't any issues with a full peel-adhere roof underlayment along with the deck is there? I've a metal roof on this task plus the underlayment are going to be completely adhered on the roof sheathing.
You might be in local climate zone five. I described the minimum amount R-values for your approach you happen to be getting in among the paragraphs earlier mentioned, during which I wrote, "In line with .
However, in some areas of the country, particularly in the Northeast, insulation contractors are actually dense-packing unvented rafter bays with cellulose For many years. Because the method has deep roots in New England, several setting up inspectors accept these kinds of installations.
one. It's Full Article always a bad idea to setup an HRV within an attic. HRVs must be obtainable enough with the homeowners to routinely alter the filter.
I am unsure when you are interested in a building science respond to or possibly a code remedy. From the code perspective, it is a roof that needs to be insulated to R-forty nine.
Doug... For a few purpose I did't see your submit #seventeen. Appears like two of us at least Believe there is likely to be a very simple economical Option.
Your plan to set up a stack of rigid foam rectangles in Every single rafter bay is known as the "Slice-and-cobble" way of insulation. It really is a technique generally picked by homeowners, but never ever picked by insulation contractors.
Just like every kind of vent baffles, it’s a smart idea to listen to airtight building techniques, particularly if you'll be setting up air-permeable insulation in the rafter bays. Seal the edges of each and every panel with caulk, and tape the seams involving panels with a substantial-excellent tape. (If you're putting in air-permeable insulation like fiberglass, mineral wool, or cellulose, the ventilation baffle isn’t optional; it’s demanded.
As for my Strength auditor recommending blowing cellulose into the mansard sides, You furthermore may advise in opposition to that? I used to be under the effect blown cellulose prevents moisture migration.
I such as the element presented but I wouldn't get in touch with that a cathedral ceiling problem as it includes ceiling joists spanning at the bottom from the roof rafters. I might contact this an insulated attic.
A. The air barrier can be a vapor barrier, because the rigid foam is likewise very likely to More Help be considered a vapor barrier (or close to it) in almost any scenario.