Insulating a 100-Year-Old Farmhouse
Hi, I’m a contractor working out my second renovation project. It’s an OLD 200 sq ft farm house in King George, Va, and I am value engineering a green build, while incorporating as many passive house principals as economically feasible. I also plan to pursue LEED certification.
The exterior wall on the original structures includes rough cut 2×4 ~24″ OC on top of a 5×8 timber sill. Original clapboard wood siding with vinyl siding installed on top of that. I would like to keep the vinyl siding and am designing the exterior wall system.
I have a ton of salvaged .25″ fan board XPS. I am thinking of installing two layers of XPS in the wall cavities against the inside of the wood siding (R-2 and water barrier). I would then use strong-ties to double up the rough 2×4’s to create 2×8 interior walls. I would then install either 8″ inches of Ultratouch Denim Insulation R-30 or 8″ of rockwool. I would then install CertainTeed Membrain on the double stacked 2×4’s to provide an air barrier. On top of the Membrain, I would seal the gypsum walls.
By stacking the 2×4’s I realize there will be a thermal bridge, but with the membrain installation, I would mitigate condensation on the exterior side of drywall.
The existing structure had log joists, which I am replacing with an insulating concrete slab (4″ of concrete, 2″ of Foam (XPS or EPS or Foam), 4″ of gravel. In the concrete, I would install radiant floor heating.
Will this work?
Appreciate feedback, thoughts, or alternatives.
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