Insulation in a 2 1/2″ space in an old wall
I am starting work on an old community hall constructed with lathe and plaster attached to 2 1/2″ strapping against boards that contain 4″ of plaster between them followed by a single wythe brick wall. The plaster is in good condition and all trim and wainscott as well — would be a shame to tear the interior finish down but certainly presents an opportunity to do a much better job of insulating.
What thoughts on this construction? I am in Ontario, near Ottawa, the building is a storey and a half over a crawlspace, not sure yet about what happens at the floor intersection with wall.
Easiest likely to build walls in with studs and fill cavities with cellulose? — with this construction perhaps not so worried about air leakage beyond detailing the openings? How helpful would a thermal break be? Could also function as an air barrier if considered helpful. Details at stone foundation? Stand off from wall with dimple membrane tied to floor/wall above for air barrier and spray foam against membrane? I don’t want to isolate one side of stone foundation by spraying the surface — also concern with older structure and reversibility of applications.
Andrew
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Please explain more clearly:
1) what you have now
2) what you would like to do
I have the empty space between plaster wall and 4" of solid plaster between boards, 1" air space and a single wythe of soft brick.
I want to give myself a tight, well-insulated building that manages a cold dry winter climate and a warm humid summer climate. I debate the expense and necessity of foil encased PIC - useful as vapour retarder and air barrier in many applications but here?
Considering building the walls out and blowing in cellulose or installing Roxul if I don't have to worry as much about thermal bridging, air leakage and vapour (paint the drywall) with this construction method.
Basement thought that providing an air space on either side of the stone allows the wall to dry to both sides -- perhaps spray with open-cell but what kind of moisture load can it handle? Still prefer the idea of a system that is reversable.
Andrew
Andrew,
Using the "search" function at this Web site, you will find many references to your questions. You might try to search for "brick insulate" or "brick insulation".
You should read or listen to this Podcast:
https://www.greenbuildingadvisor.com/blogs/dept/building-science/how-do-you-retrofit-old-building-be-energy-efficient-and-durable
To answer your question about insulating an existing stone foundation: use closed-cell spray polyurethane foam on the inside. Don't obsess about reversibility.
Andrew,
I forgot to note: I strongly advise you to read "Insulating Residential Masonry Buildings In Cold Climates" by Chris Benedict (in the the current edition of Home Energy magazine, March / April 2010).
Thank you,
I'll look through this information -- perhaps more specific questions later.