How can this look for a plan? Something you would probably improve/increase/reorder? Would you concur with taping the seams in equally levels of plywood?
Preferably, you need to have an airtight barrier over and under your fiberglass batts. If you're able to realize People two air obstacles, then wind-washing isn't a problem in a very roof like yours. (It can be inside a vented unconditioned attic, not surprisingly, In particular near the soffits.)
The initial vent baffles to strike the industry — the common Suitable-Vent of the seventies and ’80s — have been low-cost, flimsy merchandise made of thin polystyrene. Polystyrene baffles have several negatives: becoming slender and flexible, they will’t resist the pressures from dense-packed cellulose or blown-in fiberglass; they don’t ventilate the whole width with the rafter bay; and as usually installed, they permit air to leak out the best from the insulated assembly.
Q. "Ought to I bite the bullet and threat of spray foam insulation, or deliver the builders back up over the roof in December to chop ridge and soffit vents?"
To comply with the code -- and also to undertake a developing process that is a lot less dangerous -- you should possibly incorporate ventilation channels or you need to put in a layer of spray foam on the underside of the roof sheathing, subsequent the guidelines spelled out from the report on this webpage.
Whilst roof air flow can lower the potential risk of ice damming, it’s important for builders to Restrict the flow of heat into roof ventilation channels by including one or more ceiling air limitations and by putting in thick insulation, to ensure that as minor warmth as feasible escapes from the dwelling.
Like Doug's design and style, the main focus is on developing a high perm layer for drying to the exterior, that should continue to make it possible for venting while blocking wind washing from the fluffy things.
I am unsure in the event you are interested right here in a creating science remedy or possibly a code answer. From a code perspective, that is a roof that needs to be insulated to R-49.
I have now insulated the steep sides of my unvented mansard roof with six" fiberglass (and I had it inspected), does one propose I rip that out and use spray or board foam? I've gotten conflicting information on whether or not to deal with it like a wall or even a roof.
If you wish to do it suitable, you must deal with air leaks, deal with your recessed can problem, and increase adequate R-benefit to no less than meet minimum amount code specifications. It is lots of perform, but it is not rocket science. Repairing these issues could possibly be high priced, having said that.
Martin, because of your outstanding and timely guidance, we at the moment are headed towards an answer of rigid foam in excess of the outside on the ceiling. Thank you for pointing me With this new and enhanced course. We remain Doing work out some facts, such as...
Will it make sense to spray and Minimize and cobble four inch shut mobile foam/board on the original source underside of sheathing followed by fiberglass Within the bays and 1 inch of eps/iso underneath the rafter (to prevent thermal bridging) ahead of ending with drywall? Will I produce a vapor sandwich and superior leave the ultimate EPS and take the thermal bridging?
Bear in mind: Because your roof assembly is dry, doesn't suggest it's effectively insulated. Your assembly might have large air leaks that act as thermal bypasses. (Or not. It is tough to inform without a web site stop by.)
Must I take advantage of airtight baffles or not, I don't see a way to have dampness escaping inside a assembly with airtight baffles, fiberglass and xps on The within, regardless of the the dew level will probably be inside this assembly and possibly develop condensation that can't evaporate without the need of ventilation.