Hardie Siding and Hydrogap SA with foam wall assembly
Hello I am trying to build a Pretty Good Home while balancing costs/efficiency/environmental/fire protection. I live in Davenport Ca with 36” of rain and 400 feet from the ocean but also in a high fire zone. Given building costs have gone to insane levels here in CA I have had to scale back from my dream wall assembly to what I am proposing and would appreciate feedback if it makes sense as I have not seen it anywhere exactly like this. Wall assembly is 2×6 on 24” center with Plywood then 1” EPS then Hydrogap SA then Hardie (lap downstairs and board and batten upstairs) windows outtie. Hardie allows you to attach to 1” of foam directly. Windows on 1” plywood bucks. thank you
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
I’m by no means a pro, but I wonder why the Hydrogap SA is necessary. I believe you could tape/roll the seams of the plywood handle your air barrier (with some Siga Fentrim at the wall to foundation), and then use something like tyvek as the WRB.
I don’t think the plywood bucks would be necessary with that assembly; only some extension jambs as your drainage plane is at the sheathing.
You could also consider foil faced eps with tape as your WRB, but that means flashing your windows to that as opposed to the sheathing.
Hopefully a pro will chime in and offer some advice on how best to tackle that assembly.
User ...604,
I generally champion a full rain-screen behind cement based cladding, but given the current economic conditions that sounds like a pretty good wall assembly.
I could probably pull off 1/8” rainscreen without changing my plan much at all. Is that enough gap to accomplish the drying goal??
I think you are fine with what you are proposing. Cover the bottom of the foam with flashing or a strip of cement-based trim and you are all set.