Wall assembly with wood heat
Hi Everyone,
I am currently building a 1440 sq ft house in Northwestern Wisconsin 6a and was curious about the most cost-effective and efficient wall assembly that I as the owner/builder can construct. When finished, I plan on having pine board and batten, horizontal 1×4 acting as the rainscreen, GreenGuard Classic, OSB, 2×6 wall, Rockwool insulation with a smart vapor retarder or kraft-faced fiberglass insulation, and finally, drywall. So far, I only have the walls framed, sheeted, and housewrapped. I understand this assembly has an r value below current recommendations, but it is what I can afford and still passes the local code. I plan on heating with wood and running a window AC unit for a few weeks in the summer. My question is, how would you go about creating the interior air barrier? vapor barrier? Taping and sealing the smart barrier? Doing that and also sealing the drywall? Is the Rockwool worth it? What would be the best bang for the buck moving forward?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Yes in your current situation detailing the smart retarder as air tight will achieve both air barrier and vapour barrier/retarder. Depending on how confident you are with your detailing you may also wish to make the drywall air tight.
Rain screen should be vertical, or at most 45 degrees, to perform as required.
If you are somewhat concerned that the walls are not high performing, you could upgrade to better insulation. Rockwool has many good qualities, price not being one of them.
If you are energetic and have a chainsaw then I would not worry so much, when it is cold out throw another log on the fire.
You may want to consider the implications of re-sale value when making these decisions.
Hey plumb_bob,
Thanks for the reply. As a younger guy, energy is cheap, but insulation and building at this time are not. I am glad you agree with my interior detailing. Hopefully, my keep-it-simple stupid approach prevents me from making any major mistakes. With the rainscreen / furring strip detail, am I crazy to think that if I bevel a 1x3 or piece of plywood towards the backside of the board and batten that it would prevent water from causing problems?
It may work, and is better than cladding directly on the building paper, but I would look at 45 degree rain screen, or double strapping to ensure it works properly. At the end of the day these details will not add up to much for materials or labour in relation to the whole project. In 10 years you will not regret doing it correctly.
Other factors are local weather conditions like the prevalence of wind driven rain, depth of roof overhang, flashing details. I live in a climate where wind driven rain is not a concern, and a rain screen is not required by codes. And we do not typically see rotten walls from the lack of rain screen, but we do from poor flashing details.