I thank you for this impeccably timed website, as I am now framing my semi-essential cathedral ceiling hip roof (with brief ridge). I would want to explain my depth and try to understand exactly where I am on the ideal keep track of and even more importantly, exactly where I will likely have failures. Hope I am able to amuse a number of you...I come to feel much like the a lot more I try out to deal with a concern, the greater of a concern it will become, And that i unquestionably don't desire to choose fantastic time, treatment, and element to facilitate the demise of my roof.
However, I feel you're Erroneous regarding your asphalt felt; I question if the felt is impermeable to h2o vapor. Most different types of asphalt felt are to some degree permeable -- generally 5 perms when dry and approximately 60 perms when wet.
Builders resolve this issue by furring down or scabbing on supplemental framing beneath the rafters to deepen the rafter bays. A different technique is so as to add a layer of cross-hatched 2x4s, 16 inches on Middle, mounted beneath the rafters."
Code will not look to apply as it's grandfathered in. It looks like I ought to redo the hall ceiling.
If you would like use rigid foam, the very best spot to place it really is on top of your roof sheathing, not under your roof sheathing.
The very first vent baffles to hit the industry — the vintage Suitable-Vent of your 1970s and ’80s — were reasonably priced, flimsy objects crafted from thin polystyrene. Polystyrene baffles have various down sides: becoming slender and versatile, they're able to’t resist the pressures from dense-packed cellulose or blown-in fiberglass; they don’t ventilate your entire width of your rafter bay; and as generally installed, they allow air to leak out the top from the insulated assembly.
If you end up picking to set up open-mobile spray foam rather than closed-mobile spray foam, your roof assembly can dry rather to the inside. Just Guantee that the spray foam layer is thick sufficient to keep your rafter bays higher than the dew issue in the Winter season.
Superb post and discussion. I have an issue about an existing unvented attic assembly. this post The rafters are 2x4's plus the bays involving them are completely stuffed with shut cell spray foam. I want to add two 1in layers of polyiso in direction of the interior of attic and then deal with having a vapor open up membrane to airseal the assembly.
Put in a layer of closed-mobile spray foam towards the underside in the roof sheathing, and fill the rest of the rafter cavity with the air-permeable insulation. Again, this type of assembly is designed to dry to the inside, Hence the assembly ought to in no way involve an inside polyethylene vapor barrier.
Most building codes demand one square foot of Web cost-free ventilation place For each and every three hundred sq. feet of attic flooring area, assuming that 50 percent with the air flow openings are located while in the soffit, and 50 percent along the ridge.
The roof seems to have a layer of asphalt shingles about the sheathing which has a tin roof about that. The soffits are closed off. Your house is way off the crushed route and It can be hard to get any contractors on the market to work, not to mention give bids so I'm pretty much alone.
I have a partial cathedral ceiling in the finished attic of my house in zone four (TN). Each and every slope on the roof is split roughly in thirds by three distinctive cases: knee partitions within the outer thirds, "cathedral" ceiling in the center thirds, in addition to a vented "attic" in the middle third with a ridge vent - a standard situation with concluded attics, at the very least all around below. I have a giant issue in the summer with overheating. The insulation just isn't Doing the job nicely as it was poorly insulated with just R-19 fiberglass batts in between the rafters without having a ventilation baffle or satisfactory soffit venting and only r-19 blown to the "attic Area". In addition, my upstairs HVAC ducts are run while in the really sizzling "attic" Place under the ridge. Based upon what i haved uncovered from various posts in this article, my planned Option should be to cathedralize the whole roof, eave to ridge: put in continous air-tight web-site-constructed two" vent channels applying foil-confronted polyiso board (as recommended in ), setting up ongoing soffit vents to drastically improve the airflow from soffit to ridge, developing an air-tight ceiling under the rafters, and, most of all, carry the ductwork Within the conditioned envelope.
Concerning installation: When it has been productively installed in Europe for a few years, we've just gotten the material, visit the website and so we anticipate obtaining it on the occupation site before long and truly installing it - and naturally, reporting again how it went.
It is a code violation to setup an air-permeable insulation like fiberglass batts in between unvented rafters. It's also a nasty strategy, mainly because moisture can accumulate on your roof sheathing if you are trying this process, and you will end up getting sheathing rot.