Dan Reams, thanks for the feedback. I also are in snow country near Yellowstone Nationwide Park. I normally have properly about three ft of snow on my cathedral roof. I feel the dew point is frequently within the snow as an alternative to from the roof. The R price of the snow is commonly close to the R value of the roof. This can result in enormous ice dams. An easy thermal Evaluation displays that You can't set a practical number of insulation in the roof to stop the ice dams and go the dew level in the roof.
Thank you for your information, Martin. Inexperienced Developing Advisor has been the most beneficial for answering particular questions I've had in the basement the many method to the roof. I would not be capable of Make my own house solo similar to this with no you and various readers assisting me out with facts.
1. You must get an engineer To guage the security of your respective 2x4 rafters. "Furring down with 2x2s" doesn't Increase the means of your 2x4s to bear the snow load. It can be attainable that an engineer will suggest you to definitely sister 2x8s or 2x10s on to your present 2x4 rafters.
To avoid moist inside air from contacting chilly surfaces near the ridge, you need a genuine air barrier and a true insulation layer. The correct way to repair this issue is to show the rafter bays -- both from over or below, It can be your alternative -- and pull out the fiberglass insulation. Set the fiberglass in the dumpster. Then fill the rafter bays with spray polyurethane foam.
I imagine that you need to write-up a sketch. I am unable to visualize what you are discussing out of your description. If you would like set up an HRV inside your attic, How come you should set up a water-proof stucco roof in excess of some sort of EPS box? Isn't really your attic by now dry? Most attics have roofs.
Vitality codes create bare minimum R-worth necessities for roofs and ceilings. There are lots of probable code compliance paths; most builders pick the prescriptive path, which sets forth bare minimum R-values for roofs and ceilings in a prescriptive desk.
Back for the vent strategy. read what he said I actually Feel venting a roof that is airsealed in the inside very well and constructed without having vent chutes is probably The easiest way to Construct cathedral ceilings.
Q. "I am thinking if I ought to furr out the rafters to acquire the desired thickness of spray foam, or if setting up a couple of inches of polyiso foam for the underside with the rafters, after the spray foam, could work?"
1. It's usually a foul idea to install an HRV within an attic. HRVs should be accessible sufficient for your homeowners to routinely change the filter.
Are you currently thinking the 'flat' vented cavities would not supply the assembly with the exhaust path for dampness?
The GBA Site won't deliver custom aspects. That is what an architect or an engineer is for; I suggest that you just employ the service of one particular.
The wall and roof portion of Those people houses signifies that they are unvented assemblies. (Continue to unclear to me how which is Safe and sound). I assumed if I did essentially exactly the same factor, but included in excess of-sheathing vent strips for steel more roofing, I would be golden, but I do think I'm missing something in this article.
If a setting up inspector insists that you put in some kind of interior “vapor barrier,†it is possible to often set up a smart vapor retarder like MemBrain to satisfy your inspector.
I was skeptical of Monthly bill Hulstrunk's claim that AccuVent baffles could endure staying dense-packed in an enclosed cavity.