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Insulating our 110 year old brick home

Last Post 02 Aug 2011 02:27 PM by Dana1. 28 Replies.

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Yves

New Member

Posts:3

24 Jul 2011 11:33 PM
Hi jonr, "...the parapet has never been heated..." makes more sense. My mistake! Yves

Eric9

New Member

Posts:2

25 Jul 2011 07:33 AM
May I jump in with a question as well? We also have a brick structure - an old (1870) school house in nw PA. The soft brick walls are 3 courses thick with air gap between the courses - enough room for mice to travel back and forth. We also are hoping to frame and insulate on the interior. My initial thought was to proceed in this order: drywall, 1/2" blue board, 2X4 studs, weather resistive barrier (lowes housewrap), brick. Between the studs I had planned to cut and fit blueboard (perhaps up to 2" thick) and use spray foam from the can around the edges to make a better seal. Upon reading the initial posts, this may not be adviseable. To avoid moisture problems with the wood/brick interface and build wisely - is there a better order to follow? Also, would I be better advised to use the polyiso rigid board between the studs, rather than the rigid blue board? I have been searching for info for quite some time and this thread has already given the most specific info by far. Thanks in advance for any help you can give. Eric

jonr

Senior Member

Posts:5341

25 Jul 2011 11:59 AM
I would stick with the standard method of rigid foam on the outer side of the new wall. Yes, with cellulose or fiberglass between the studs.

Eric9

New Member

Posts:2

25 Jul 2011 04:02 PM
Thanks for the quick response. So the standard order would be: drywall, studs, 1/2" blue board, brick? Insulating between studs with cellulose or fiberglass.

jacob818

New Member

Posts:5

27 Jul 2011 12:13 AM
How energy efficient home can me made using brick instead of concrete or wood? I'm sure there is some type of building material that resembles brick, but insulates your home in a similar way. I'm hoping to find some kind of material that has been recycled. This is something that my clients are really trying me to build them an extremely eco-friendly modern home.

<a href="http://angieslist.com/companylist/seattle/remodeling.htm">Seattle remodeling</a>

jonr

Senior Member

Posts:5341

27 Jul 2011 01:40 PM
I would say drywall, taped vapor retarder, studs, 2" taped blueboard, brick.

Dana1

Senior Member

Posts:6991

31 Jul 2011 01:41 PM
With 2" of XPS (R10) between the fiber-insulated studwall and the brick there's no point to an interior side vapor retarder in a nwPA climate. the cold edge of the studs can't accumulate winter moisture from the interior with that much exterior R, and a vapor retarder on the interior would only impede drying. If only 1/2" XPS is used (R2.5) an interior side vapor retarder would be useful. But with anything more than R5 in exterior foam it would be better (the wood stays drier) if leave it out, and use only standard interior latex paint as the interior vapor retarder. Where joists etc are in contact with the brick it's better to leave an 8-12" clearance where you use use only 1" closed cell foam on the brick rather than 2" XPS.

jonr

Senior Member

Posts:5341

31 Jul 2011 10:38 PM
would only impede drying And block air flow (a good and vitally important thing). can't accumulate winter moisture It can condense, depending on humidity and temperature and how much in-wall circulation you are getting because you skipped the interior vapor/air barrier. Condensed water then tends to wet things around it (like studs). That being said, you could get only paint to work.

Dana1

Senior Member

Posts:6991

02 Aug 2011 02:27 PM
With R1.5 of masonry + R10 of foam and (at most) R4 of stud, the temp at the stud edge will NEVER be below the dew point of anything but a tropically humid interior. At center-cavity with R12-R13 of fiber and ~ R12 of exterior foam + masonry the temp at the foam will be below 40F (the dew point of 70F, 35% RH room air), fewer than 1% of the winter hours for most nwPA locations, and even those fleeting condensation events are of no consequence, since neither the foam nor the fiber is damaged by that faint haze of fog forming on the foam, nor will it lose any thermal performance during the condensation events. An interior air barrier is always a good idea (even necessary to achieve the R-performance of low density fiberglass, less so for cellulose), but it can be highly vapor permeable without negative consequences in that climate.