Stone and Timberframe Renovation
I am looking at a 1,200 square foot one story renovation of a 150 year old stone rubble building with timberframe roof in Western Massachusetts – climate zone 5.
Exterior stone bearing walls are 1′-8″ thick with direct applied plaster interior. The exposed timbers are built like a truss with planking spanning four feet with very small (5″ wide) slate roofing applied directly to the planking. It is in very good condition and is to be used as a non-profit nature center for children.
Since the building, which was previously used by a Girl Scout troop, has been abandoned for several years, it must comply with current building code requirements. Questions being raised have to do with insulating and air sealing this structure while maintaining its look from the exterior and not losing much space or the timberframe on the interior.
I feel that the roof would be best insulated from the exterior with SIP panels or reframed and cellulose, then reroofed. As for the interior, a layer of polyiso, strapping and drywall.
Am I headed in the right direction?
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Replies
Jon,
Your ideas are fine. My advice:
1, Carefully strip the slates so that they can be reinstalled later.
2. Install a new SIP roof.
3. Although your plan to install polyiso on the interior walls will work, you might consider building new 2x4 walls on the interior, spaced a few inches away from the existing plaster, and then filling the 6 or 7 inch space with closed-cell spay polyurethane foam. That would give you an excellent air barrier.
Thanks Martin,
I was hoping not to lose much of the interior square footage with the rigid application on the interior walls. Stripping the roof slate for re-use sounds like the right thing to do, but may prove cost prohibitive.
Jon,
If you're calculating whether or not saving slate is cost-prohibitive, remember:
1. Slate has a high salvage value. You can sell it if you don't want to reuse it.
2. It's possible to offer the slate to anyone willing to strip the roof.
I always shed a tear when I hear that slate has ended up in a dumpster.