I have an unfinished attic, with cathedral ceiling, no insulation at the moment. in 5-10years we will probably be incorporating dormers, but Meanwhile i want to add insulation and drywall in The best, most reversible/salvageable way. My system is to hang two levels of 2 inch polyiso under the rafters, taped with staggered seams leaving the rafters empty, so basically a vented assembly. I have extra blocking to the floor joists and could make the polyiso steady from the knee partitions. I thought I'd personally incorporate furring strips in addition to the insulation then hold drywall, believing that the furring strips would generate an airgap, allowing the foil to work as a radiant barrier.
Martin, re: altering the attic over the 2nd Tale bedrooms to your conditioned attic and sealing the soffit vents.... Ahead of this most up-to-date plan about insulating with rigid foam along with the cathedral ceiling, we had been planning to Slice a ridge vent into your gable ridge, as a way to meet up with air flow code demands. Now Now we have eave vents additionally two quite worthless gable vents, one particular on either side.
We actually Really don't know if these roofs have good vent channels, or which kind of vent baffles (if any) ended up utilized to keep up the air flow hole between the very best of the fiberglass insulation along with the underside of the roof sheathing.
When roof ventilation can assist dry out damp roof sheathing, it’s necessary to limit the circulation of water vapor escaping with the residence so that the roof sheathing hardly ever will get damp to begin with.
By Martin Holladay
Insulated cathedral ceilings are a comparatively recent phenomenon. The fad for insulated cathedral ceilings (and great rooms) definitely took off in the 1970s and nineteen eighties, when illustrations started appearing like mushrooms after a warm rain.
Your decide to use 2-inch-thick EPS as your ventilation baffle will do the job. The EPS is rather vapor-permeable, so it allows a little bit of outward drying. (In any case, in case you Develop a fairly airtight ceiling, news there won't be any dampness In this particular assembly that should escape.)
The for a longer period which you hold out to set up rigid foam over your roof sheathing just after your rafter bays are filled with fluffy insulation, the larger the danger that the roof sheathing will accumulate humidity. 1 or 2 a long time must be no difficulty, but I would not stretch the exercise much farther than that.
Why not just do it correct as well as Create with force handled roof sheathing. Even typical plywood can take care of wetting cycles many times in excess of our number 1 Tremendous inexpensive OSB.
Should you be choosing to build a vented roof assembly, don’t ignore to include soffit vents and ridge vents.
Okay, I had been figuring that the full from the rigid foam + cellulose needed to be a particular R-worth together and were pondering employing significantly less rigid foam. I have been looking through about unique styles of cellulose. Considering that I am putting in from previously mentioned would a little something like stabilized cellulose function as it has a little bit drinking water included?
I have a partial cathedral ceiling within the concluded attic of my household in zone four (TN). Each and every slope of your roof is split roughly in thirds by three unique situations: knee partitions at the outer thirds, "cathedral" ceiling in the center thirds, in addition to a vented "attic" in the middle 3rd using a ridge vent - a common situation with finished attics, at the least about listed here. I've a giant issue in the summer with overheating. The insulation is not Doing work perfectly mainly because it was poorly insulated with just R-19 fiberglass batts amongst the rafters without a air flow baffle or sufficient soffit venting and only r-19 blown into your "attic Place". Moreover, my upstairs HVAC ducts are run in the truly sizzling "attic" Room under the ridge. Dependant on what i haved learned from various articles right here, my planned Answer would be to cathedralize the whole roof, eave to ridge: put in continous air-tight site-crafted two" vent channels making use of foil-faced polyiso board (as suggested in ), putting in steady soffit vents to significantly improve the airflow from soffit to ridge, generating an air-tight ceiling down below the rafters, and, most significantly, carry the ductwork inside the conditioned envelope.
A. Either strategy will work, provided that you get not less than the minimal code R-price to your roof, and providing you use construction procedures that listen to airtightness.
Whether or not you choose to make it vented or unvented, get the small print right — for the reason that each cathedral ceiling gives alternatives to make massive issues