1. It's always a foul idea to install an HRV in an attic. HRVs should be accessible more than enough with the homeowners to routinely change the filter.
The strategy: Element A: I stumbled on 1" Dow rigid foam backed five/8CDX for a similar cost because the bare CDX, And that i plan to double it up similar to a SIP, installing the bottom sheet foam facet up and the subsequent sheet on best (staggered certainly) with the foam going through down, providing me two" of insulation between the plywood.
A. The air barrier can be a vapor barrier, since the rigid foam can be more likely to be a vapor barrier (or close to it) in almost any situation.
Certainly, it is actually Harmless (Despite the fact that prior to deciding to question an issue about a particular roof assembly, It might be superior to learn your local weather zone).
By Martin Holladay
A further issue is, need to I carry on the identical insulation assembly outside the house? The last impression reveals a significant ten' overhang. Should really I vent this exterior part or seal the underside of the p.t. plywood deck While using the closed-mobile insulation?
Dan Reams, many thanks for your personal reviews. I also reside in snow country around Yellowstone National Park. I normally have very well in excess of three toes of snow on my cathedral roof. I feel the dew issue is frequently in the snow as an alternative to in the roof. The R value of the snow is often near the R price of the roof. This can cause large ice dams. A simple thermal analysis displays that You can't put a realistic level of insulation within the roof to avoid the ice dams and shift the dew position into your roof.
Thanks on your response Martin. Would you still be happy to utilize that unvented process for a renovation circumstance exactly where there is non-breathable membrane (eg bitumous 'felt') previously mentioned solid board sheathing?
The sides in the roof are included with asphalt shingled (GAF Slateline being exact). It feels like I should pull down the fiberglass and have it spray-foamed ahead of I drywall.
We want to add monitor lights to The brand new ceiling, with its electrical supply jogging throughout the new cavity developed for that insulation. The present supporter also demands its electrical provide to run by means of that House.
Apart from inquiring you visitors for a review of my plan, I have Yet another problem brought about by considerations expressed by a neighborhood builder. He is worried that after the AC ducts are inside the conditioned Area that the ducts will be liable to sweat and may drip all over my home furnishings.
I am a homeowner with cathedral ceilings that were additional through transforming and enlargement of my home while in the late 90s. Just the ridge beam is exposed. The rest of the ceiling is roofed with drywall. In the several years there has been some condensation leak down the facet of your ridge beam on some mornings in March/April.The house is about four miles within the Coastline in Southern Califonia, so zone 3b. You can find 4 recessed lights inside the ceiling to the aspect of the beam that will get the condensation, but In addition there are lights within the aspect that is often dry. There's no air-con in the house. Heat is employed over the night only a couple of dozen nights a year, not through the condensation. Commonly the windows are open. It appears the condensation displays up on mornings when there isn't any marine layer (no clouds each morning) along with the temperature heats up rather early following a pretty neat night. The situation ceiling faces east/west along with the condensation is around the east facing aspect from the beam. The roof is black asphalt shingle. I know that there is no caulk/sealant concerning the side from the beam and also the put where the drywall butts in opposition to it, so You will find a little air gap there.
Producers of soffit vents and ridge vents ordinarily specify the net totally free vent region in their merchandise on solution packaging or in technical specs imp source offered on line.
This can be an alternative I'm looking at in my home to avoid wasting the former owners recently installed roof shingles, even so the depth in the rafters cannot accomodate plenty of insulation to meet code. I'm questioning if I need to furr out the rafters to acquire the specified thickness of spray foam, or if putting in a couple of inches of polyiso foam on the underside in the rafters, after the spray foam, could perform?