Cost-Effective Energy-Smart Wall Assembly
Back story. Building my first and personal home. My plan all along has been to flash and batt. Because of Covid and costs our budget like any one else’s is hemorrhaging. Because that was my plan I didn’t air seal from the outside. I will have an unconditioned vented attic.
I live in southern MN. Zone 6. In a pinch I’ve been researching and reading for 2 days straight trying to find a cost effective way to make my house as tight as possible and insulate. My potential plan and questions are below I’m praying someone with have the time for some valuable input on.
Caulk every stud bay all the way around where the OSB Sheathing meets the framing. Caulk top plates, double studs, bottom plate (slab on grade foundation), headers, studs along top and bottom plate and around the face of the stud to top or bottom plate (Everywhere). Closed cell foam for any small or tight bays I cant get at with caulk. Foam all windows and doors. Spray back of electrical boxes, and caulk the gab between the rock and boxes in the front.
Spray closed cell foam over framing to sheetrock joints. Spray all can lights, electrical boxes, ect.
Insulate walls with:
Rockwool or OC Thermafiber – Walls – Spending a little more here over fiberglass makes sense to me and is still half the cost of the flash and batt.
20″ cellulose – Attic.
Any issues with the proposed route? Any different suggestions?
The infamous do I need a vapor barrier question? But for real should I use something like membrane? It seems from all the reading that I don’t need either if I just create a vapor retarder with my paint and do a good job air sealing. This applies to both the ceiling and walls correct?
I considered the “Airtight Drywall Approach” but I feel like over time and especially after the first couple of years I wont want to address any small cracks that end up popping up.
Any suggestions on caulk? It seems as though I want an acoustical caulk that never sets up? Something like OSI SC175? Green Glue seems spendy? What have you guys used and had success with that doesn’t break the budget?
If I overlooked something or you have any questions obviously ask and I’ll get back to you.
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