Wall/Roof Design Strategy-Zone 2- South Louisiana
I am designing our family’s forever home and have done a ton of research, but I can’t decide on the wall/roof sections and would like recommendations. I am bought into the concept of a high-performance home, but I need help determining the cost-to-benefit ratio of all the high-performance home options. I understand air sealing is critical and plan on tasking my builder to air seal the home properly, but I would like recommendations on Wall/Roof Sections.
My current plan is as follows:
Conditioned Attic because HVAC Equipment will be stored in the Attic
Wall-90% Brick, Tyvek, OSB, 2X6 Walls, 5 ½”
Questions: Should I consider ZIP at 2-3 times OSB Cost? Should I use spray foam, cellulose, or wool insulation?
Roof- Arch Shingles, Stick on Underlayment, Taped Seams, OSB,
Question: I would like recommendations on insulation types and thickness.
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
I would check out exterior insulation and see what the up charge would be by your builder. If you have to go with the assemblies you listed, my vote is blown-in fiberglass for the walls. Since you are using brick I would strongly recommend looking into Mortar Net or Delta Drain-and-Dry lathe to maintain your rain screen behind the brick.
For the roof, your peel-and-stick underlayment will be your air sealing layer so there is no need to tape the seams of the roof OSB panels. For insulation, unless you are willing to consider exterior insulation your only option is closed cell spray foam, unfortunately. It needs to be a conditioned attic as you mentioned so the insulation has to go along the roofline. Closed cell is safer than open so that indoor humidity does not rise through the foam and condense on the underside of the roof sheathing.