Ideally, you need to have an airtight barrier over and under your fiberglass batts. If you're able to accomplish Those people two air barriers, then wind-washing is not an issue inside a roof like yours. (It may be in a very vented unconditioned attic, obviously, especially near the soffits.)
If you put in 2x4s (or 2x3s on edge, put in with extensive screws) perpendicular into the rafters, you might handle most of the thermal bridging problem without the need to include a layer of rigid foam.
Should I take advantage of airtight baffles or not, I don't see a means to have humidity escaping in a very assembly with airtight baffles, fiberglass and xps on the inside, whatever the dew stage will be inside of this assembly And perhaps create condensation that can't evaporate without ventilation.
Another problem is, ought to I proceed exactly the same insulation assembly outside? The final impression reveals a significant ten' overhang. Must I vent this exterior portion or seal the underside on the p.t. plywood deck While using the shut-cell insulation?
I thank you for this impeccably timed blog, as I am now framing my semi-fundamental cathedral ceiling hip roof (with quick ridge). I would want to explain my element and check out to know where by I'm on the ideal observe plus more importantly, exactly where I could have failures. Hope I'm able to amuse many of you...I sense similar to the a lot more I try to deal with a concern, the more of a priority it turns into, and I surely don't need to get terrific time, care, and element to aid the demise of my roof.
Certainly a cathedral ceiling depth might be incredibly related although the obstacle of numerous cathedral ceilings is definitely the included structural aspects, electrical containers, and the will for wood board ceilings all which get started compromising the drywall layer which in the detail is applied in the air barrier.
I applied to work for a roofer, and roofs that are fully lined with Ice & Water Defend make me nervous. I see this kind of structure as lazy and potentially problematic.
Very first, is it straightforward to establish no matter if a roof is ventilated? If no soffit vents or side vents are noticeable within the roof from the bottom, does that suggest the roof is just not ventilated?
As building scientist Invoice Rose has shown, code requirements for roof venting were by no means determined by exploration or scientific ideas. Inside of a perfectly documented JLC
The ideal method to visit here move read review forward is to install rigid foam over the roof sheathing. There actually are not two solutions to this concern. Time to do the do the job is currently. If the contractor will never complete the required work, you'll need to rent another contractor.
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I am creating a forensic laboratory produced in Massachusetts, and am having a difficult time reconciling applicable making code with my read through in the literature pertaining to insulation and roof deck condensation.
Here is a url to your GBA element for an insulated roof assembly with vent channels previously mentioned the roof sheathing and steel roofing:
This is an option I'm considering in my home to avoid wasting the earlier owners newly installed roof shingles, nevertheless the depth with the rafters simply cannot accomodate ample insulation to fulfill code. I am wondering if I should furr out the rafters to acquire the desired thickness of spray foam, or if installing several inches of polyiso foam into the underside of the rafters, once the spray foam, could do the job?