Though vented roof assemblies are made to dry to the outside, unvented roof assemblies are built to dry to the inside. That’s why an unvented roof assembly really should in no way include interior polyethylene.
Your proposed assembly is really a code violation. If you need an unvented roof assembly, you must maintain the roof sheathing warm with spray foam or rigid foam. Cellulose insulation is assessed as an air-permeable insulation and can't be used in such a roof assembly.
Our cooler mornings may make the interior of my metallic roof sheeting to sweat a bit considering that It'll be in connection with the hotter unvented fiberglass-insulated purlin "cavity" underneath. Once our warm Caribbean sunshine starts to kick in I want this dampness to dry and/or diffuse out of the cavity, throughout the gypsum sheeting, in the cathedral living Area beneath, to then be blown outside of my 4x3 gable window. A vapor barrier would wholly retard this method.
Regarding dense pack cellulose: not sure why dense pack will be negated - I do think it perfectly suited.
It really is good to add foam board earlier mentioned the roof deck even with the shut cell foam-board (what form?) on the interior. Roof decks can not dry to the outside as a result of 0.1 for every shingles anyway, notably considering the fact that in zone five it can commit a major length of time lined in snow/dew/rain While using the dampness generate heading inward, not outward.
Nearly all of the data I operate throughout appears to be in the cellulose field that claims wind-wash is a major challenge with fiberglass; and in the fiberglass sector which asserts the cellulose group overstates The problem and that for the extent wind-wash occurs it is actually inconsequential.
one. Take away the can lights and throw them absent. Recessed can lights must hardly ever be installed in an insulated cathedral ceiling.
I suspect that Bill Rose is right: most of these failures require moisture that may be carried by relocating air. They are not diffusion failures. In the event the rafter bays genuinely are thoroughly dense-packed -- a big if -- the chance of air movement is rather minimal.
Q. "Really should I bite the bullet and hazard of spray foam insulation, or ship the builders back up to the roof in December to cut ridge and soffit vents?"
The best approach to progress is to setup rigid foam previously mentioned the roof sheathing. There really aren't two answers to this issue. Time to carry out the get the job done has become. In case your contractor will not execute the required function, You will need to hire a unique contractor.
I've a number of issues that include lots of the subjects that you've got protected in these content, but I am endeavoring to use them inside a retrofit situation. We are working on upgrading the Electrical power efficiency, which view it include included/updating insulation, for our Just about a hundred year old 2-one/two Tale balloon frame home (stucco around lathe exterior).
What does a median particular person with my job title make in another town or set of cities? Is this career stagnating in People destinations, or is there enormous development in those different types of Positions lately?
As I discussed inside the article on this site, You cannot use fluffy (air-permeable) insulation in an unvented roof assembly unless you include things like rigid foam or spray foam previously mentioned the fluffy insulation.
The roof was shingles on t&g pine decking. Insulation was correct up towards that pine decking considering that 77 and is 2014. Stuff seems like it had been set up yesterday. Not a foul place wherever, no roof vents entirely unvented roof.