Insulating while rebrownstoning?
We’ve just started to rebrownstone our facade. Our contractor has chipped down the surface before applying the slurry coat. I can now see the huge air gaps between the masonry and the window frames. I’m assuming that while the exterior wall is “open”, this would be a great opportunity to add insulation. So how should we proceed? Can our contractor do this with spray-in foam — he’s willing though doesn’t seem to have had this request before — or do we need to bring an insulation sub-contractor? For timing/convenience reasons, I’d rather do the former. But perhaps we need a more professional approach. Any advice welcome.
anonymous
in Facade and Brownstone Repair 14 years ago
3
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3 replies
jonathanpatr | 14 years ago
If you seal around the windows with a low expansion foam you are stopping air flow and insulating with a high R value material around the windows. If you are thinking about the convection that happens in the gaps on the interior of the facade brick surface, then first of all BRAVO to you!! This could be a time of experimentation, but it might be a little expensive. I am using an air sealing roll on the interior of a brownstone renovation to create a continuous air pressure boundary. The product is water based and low VOC. Once you have done the air sealing then the insulation will have still air to capture as a thermal barrier. In your case you have to stop all of the air leakage you can on the front and back walls. So air seal with the Low Expansion foam, let them finish the exterior and ask them to take any measures they are comfortable and experienced with to air seal the exposed surface before the top coat. It would be great if they could use a permanent membrane type of air barrier on the exterior before the top coat. There may be materials out there but they are probably not in wide use as of yet. An alternative is to insulate the interior walls around those windows with blown cellulose. In high enough density cellulose is a fine air seal and an excellent insulator. Remember though, if you tighten up your brownstone make sure you have enough ventilation make up air to maintain healthy indoor air quality. People who do energy audits can help you assess this part. good luck and get green!! Jonathan Flynn
brucef | 14 years ago
I’m not positive which gaps you are referring to, but I can give you some guidance on “gap” insulation. The major part of the low hanging fruit of insulation is cutting air infiltration, ie sealing leaks. I am assuming from your post that new masonry should seal air leaks? Spray foam is available in various formulations, high heat, expanding, non-expanding. Around window frames you want the non-expanding variety. The “normal” expanding foam is remarkably strong in its expansion, which will bind window frames, door openings. Pick up a case of the correct foam, and liberally apply. You cannot clean the stupid tubes, so cracking a can means using it up or throwing it away. I wear latex gloves, and try to prevent getting it on things. (As opposed to making a mess and planning on easy clean-up) We happen to purchase the foam at Kamco, but there are many sources.
slopegirl | 14 years ago
have heard Federal Conservation recommended many times on this forum. Call them, it can’t hurt to hear what they have to say…. if you’re doing it, it makes sense to do it right, and sounds like your guy doesn’t know for sure what that is.