If you wish to install a combination of rigid foam along with your roof sheathing and air-permeable insulation concerning your rafters, you need to ensure that your rigid foam is thick plenty of to keep your roof sheathing previously mentioned the dew point.
Many thanks - This is often new design, I am the designer / builder, and the more I check out it, I'm liking all rigid - less fussy. The top layer of rigid around fluffy can make my eave far too thick anyhow. The air barrier with the T&G ceiling is in fact the sandwich of felt and taped 3/8" CDX.
Your strategy to put in eight inches of rigid foam is a great one, however you might be able to set up thinner foam when there is a persuasive rationale to take action. Needless to say, eight inches of rigid foam has a higher R-worth, and will conduct far better, than the usual thinner layer.
Ken's detail (#ten) does a great job of chilly climate safety. It's what we are searching for: Excellent airsealing at the inside, fluffy things in the center, and good drying channels for water vapor at the top. By altering from a lower permeability sheeting to some significant permeability membrane (at top) with venting previously mentioned, there is absolutely no a lot more worry for roof rot although simultaneously wind washing is prevented inside the bays with the air & water limited membrane with taped edges and seams. It appears to me to generally be an extremely sturdy assembly.
Working with ventilated nailbase panels is a wonderfully great way to construct a cathedral ceiling. Precisely the same guidelines implement as when utilizing SIPs: make certain that the seams are sealed to generally be as airtight as you can make them, and make sure that the entire R-price of your roof assembly fulfills or exceeds minimal code R-price needs.
You might be proposing a vented roof assembly. For just a vented roof assembly, the code does not have to have that any foam insulation be placed in immediate connection with your roof sheathing -- on the contrary.
You are not the sole man or woman using this type of concern. For individuals who (such as you) are concerned about the issue, there are two alternatives:
Will it seem sensible to spray and Slash and cobble 4 inch shut cell foam/board on underside of sheathing accompanied by fiberglass Within the bays and one inch of eps/iso under the rafter (to halt thermal bridging) before finishing with drywall? Will I make a vapor sandwich and better leave the ultimate EPS and take the thermal bridging?
Most creating codes require one square foot of Internet free air flow spot for every 300 sq. toes of attic ground area, assuming that fifty percent of the ventilation openings are located inside the soffit, and fifty percent together the ridge.
This informative article was very educational and appeared to give a whole lot of advice on cathedral ceilings. But what what my excellent storm? Your house is 30 yrs outdated (eighty's) and im sure the ceiling isn't air restricted. I want to do anything this summer season/tumble to try to repair these leaks but I am concerned that whatever I do wont operate and can be a squander of money, Specifically given that I havent heard about a solid solution.
Given that I have discussed the appropriate way to do it, I will likely Allow you to are aware that Many of us have finished Anything you suggest.
You explain your proposed air barrier as "taped felt." I do not Believe asphalt felt may be productively go to this web-site taped, and I do not believe that asphalt felt can make a very good air barrier.
Who lives in these metropolitan areas -- do the people skew youthful or aged? How racially or ethnically assorted could be the inhabitants in these towns?
Strength codes set up minimum R-benefit prerequisites for roofs and ceilings. There are numerous probable code compliance paths; most builders choose the prescriptive route, which sets forth minimal R-values for roofs and ceilings inside a prescriptive desk.