I have an unfinished attic, with cathedral ceiling, no insulation at this time. in five-10years we will be incorporating dormers, but Meanwhile i would want to incorporate insulation and drywall in The best, most reversible/salvageable way. My system is to hang two layers of 2 inch polyiso under the rafters, taped with staggered seams leaving the rafters empty, so fundamentally a vented assembly. I have additional blocking to the floor joists and could make the polyiso continual inside the knee walls. I thought I might include furring strips on top of the insulation then hang drywall, believing that the furring strips would build an airgap, making it possible for the foil to act as a radiant barrier.
More information regarding how to insulate an unvented roof assembly is supplied from the article on this webpage.
Amazingly practical (five*) thread. So, if you will need to use fiberglass insulation batts, and you simply dont have entry to spray foam or closed mobile boards, what do you do? I assume the key is to really make it unvented and incorporate in other air-impermeable layers. I'm about to insulate a fresh all-metallic cathedral pitched gable roof while in the Caribean. The strategy is to fill the cavity amongst the 4" Z-purlins with R-eleven batting (vapor side experiencing the living Room). For additional warmth conduction resistance we intend to roll Yet another thinner (filleted?) layer of the batting excessive with the purlins (ie between the purlins as well as sheeting).
You should utilize Ice & H2o Shield as an air barrier If you prefer. But when you decide on to utilize that item, you'll have to eliminate the asphalt felt so that the Ice & H2o Shield could be adhered to your roof boards.
Your plan to install a stack of rigid foam rectangles in Each individual rafter bay is called the "Slice-and-cobble" technique of insulation. It really is a technique frequently picked out by homeowners, but never decided on by insulation contractors.
Joe Lstiburek: "A vented attic, exactly where insulation is placed on an air-sealed attic floor, is The most underappreciated setting up assemblies that We now have from the heritage of setting up science."
My experience would be that the dew level profile would turn out during the XPS foam board, therefore a VB needs to be placed on to start with deck. To be able of assembly:
Till not long ago, constructing codes expected that insulated sloped roofs involve air flow channels directly beneath the roof sheathing. Quite a few builders continue to abide by this time-tested approach.
You will be proposing a vented roof assembly. For any vented roof assembly, the code does not call for that any foam insulation be positioned in direct contact with your roof sheathing -- on the contrary.
Many thanks Martin - Now I see why my original program to get a SIPS envelope was so elegantly straightforward. It appears like min R-10 sprayed under the roof sheathing after which an entire-fill with the bays with batt / fluffy, along with a vapor sealed drywall lid can get me the 'warm' (unvented) roof program the SIPS was with the get go.
S. Bureau of Labor Data and demographic data with the U.S. try this website Census Bureau. In all situations, the info sets made use of are the most recent obtainable; as the U.S. Census is conducted just once a decade, we have adjusted the demographic info based on the most recent yearly American Local community Survey to reflect populace alterations.
If it looks like I'm outside of my depth listed here... yeah, you bet, I'm. I'm simply a homeowner, with only some days of Web investigate beneath my belt. Nevertheless the contractor isn't aware of this roofing method, so we're needing to figure it out collectively. Take pleasure in your assist immensely.
Make certain the roof assembly is as near airtight as you can also make it. In case you are employing fluffy insulation, you would like two air barriers: one beneath the insulation, and 1 higher than the insulation.
If you'd like to put in a combination of closed-mobile spray-foam on the underside with like this the roof sheathing and air-permeable insulation amongst your rafters — an approach from time to time called “flash and batt†— the constructing code involves that spray foam (or, arguably, rigid foam insulation) be “utilized in direct connection with the underside with the structural roof sheathing†and which the foam insulation meet the necessities “laid out in Desk R806.