You aren't the only particular person with this particular problem. For people who (like you) are concerned about The difficulty, There's two selections:
What obtained me commenced on the "air limited partitions and roof sheathing" was your report of a similar name; particularly South Mountain Company's wonderful posting over the Martha's Winery housing progress. I saw Marc's presentation on All those homes at BBD also.
If you end up picking to put in open up-mobile spray foam as opposed to shut-cell spray foam, your roof assembly can dry considerably to the interior. Just Make certain that the spray foam layer is thick enough to maintain your rafter bays earlier mentioned the dew issue throughout the Wintertime.
If you would like use rigid foam, the best spot to place it is actually along with your roof sheathing, not beneath your roof sheathing.
And finally, I kow the recessed lights is horrible, but what am i able to do whether it is by now installed? With one of the lights I altered it above to a pendant mild which lessened the heat close to the roof even so the air barrier remains a problem.
On the other hand, I believe you're wrong regarding your asphalt felt; I question In case the felt is impermeable to drinking water vapor. Most kinds of asphalt felt are rather permeable -- ordinarily five perms when dry and around 60 perms when damp.
I previously sprayed and Lower cobbled 4 inch of closed mobile. I will redo the roof up coming calendar year, but I suppose now it is too late to check out this site think about eps/iso on top of roof because i previously unvented the attic.
If you would like set up a mix of shut-cell spray-foam on the underside from the roof sheathing and air-permeable insulation involving your rafters — an strategy at times known as “flash and batt†— the developing code involves that spray foam (or, arguably, rigid foam insulation) be “applied in immediate connection with the underside with the structural roof sheathing†and the foam insulation meet the necessities “laid out in Table R806.
"Once you have mounted the code-mandated thickness of rigid foam earlier mentioned your roof sheathing, you’re free to setup just as much fluffy stuff as you desire involving the rafters."
Why not just do it proper as well as Create with stress dealt with roof sheathing. Even typical plywood can tackle wetting cycles repeatedly in excess of our number one Tremendous affordable OSB.
I believe that Monthly bill Rose is right: these failures include humidity which is carried by going air. These are generally not diffusion failures. If the rafter bays truly are thoroughly dense-packed -- a large if -- the prospect of air movement is quite low.
The system is to set up it (from the inside of your house) in regards to the very same time the drywall is put up. I'll instruct my crew to be sure there are no air pockets during the purlin cavities & no air move to the latter.
Install rigid foam insulation over the roof sheathing and air-permeable insulation concerning the rafters. Such a assembly is made to dry to the inside, Hence the assembly ought to hardly ever consist of an inside polyethylene vapor barrier. If you decide on this technique, it’s doable (while not necessary) to set up vent channels involving the highest in the rigid foam and the best layer of roof sheathing by installing a number of parallel 2x4s — a single previously mentioned Every single rafter — her explanation extending from soffit to ridge. (For more info on this tactic, see How to setup Rigid Foam On Top of Roof Sheathing.)
We system to transform to an improperly vented cathedral ceiling to an unvented one particular. Sealing up the soffit vents is actually a no-brainer. What is The simplest way to cope with the ridge vent? Many thanks!