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Matt: I read your earlier post and since no one else is biting I’ll offer this:
Why only 1/2″? In my experience Extruded polystyrene at R5/inch is very cost effective. Use the shiplap variety, install it tightly, and if you run a bead of acoustical sealant in the joints it will act nicely as an ‘air barrier’ >> the latest hook in the science of wall systems. You won’t need that bleeping housewrap junk, and if you drywall the interior and paint, you create what is now called a Vapour Diffusion Retarder; the latest theory is that you then won’t need a vapour barrier because without convection through the wall there won’t be any moisture. And if you really want to curry favour with the resident gurus on this board you’ll insulate with blown in dense pack cellulose.
Only the messenger
Patrick
Replies
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Matt: I read your earlier post and since no one else is biting I'll offer this:
Why only 1/2"? In my experience Extruded polystyrene at R5/inch is very cost effective. Use the shiplap variety, install it tightly, and if you run a bead of acoustical sealant in the joints it will act nicely as an 'air barrier' >> the latest hook in the science of wall systems. You won't need that bleeping housewrap junk, and if you drywall the interior and paint, you create what is now called a Vapour Diffusion Retarder; the latest theory is that you then won't need a vapour barrier because without convection through the wall there won't be any moisture. And if you really want to curry favour with the resident gurus on this board you'll insulate with blown in dense pack cellulose.
Only the messenger
Patrick
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Fred
Indulge a curiosity. Why is Sealed ductwork so important? And how is my fellow Canadian building his "iron clad exterior moisture barriers"?
Ever inquisitive
Patrick
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Thank you both for your thoughts...
Fred:
If I read you correctly, you are confirming my concerns about creating, in effect, 2 " Vapor Diffusion Retarders" with a dead space in between. A bad thing…. Thanks for the valuable advice.
As long as I have you ear, I'd like to ask you another question or two, if I may. How long would you estimate the blown in wet cells should dry before the interior wall covering is applied - say in 85 degree daytime temperatures with maybe, 85% relative humidity, and, are there commonly available methods for accurately testing the moisture content of the newly blown-in cells? As you can see, injecting all that moisture into the structure concerns me.
TIA
Patrick:
I won't be using thicker than 1/2" sheathing as that would require jamb extensions on all window and door openings. Also, other than 1/2" sheathing is not available in these parts by other than special $order$.
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I want to use 1/2" extruded polystyrene (XEPS) or expanded polystyrene (MEPS) as sheathing on a house that will have brick veneer, but am concerned about the rigid polystyrene's inability to pass moisture. I guess the 1/2" rigid poly sheathing will yield about an R 2.5 insulation value. I would also like to use house wrap as a draft stop, between the sheathing and the brick veneer.
I am in the mixed heating/cooling climate of NC. The walls will be tightly sealed at the drywall and there will be a vapor barrier between the drywall and the ~R15 insulation.
Is this a good configuration or is there other 1/2" sheathing that I should consider as an alternate material?
TIA
*No opinions?Let me restate: What is the best 1/2" sheathing to go under brick veneer?Thanks