Insulating / fixing insulation on a soft brick building
After receiving informal advice from a supposed professional, we have discovered that we insulated our 1890’s Iowa soft brick building in, probably, the worst manner possible – a vapor barrier between the brick and stud wall, batting between the studs, and drywall. Luckily, we discovered the problem before there was significant moisture accumulation but we have to remedy the situation before it is further compromised.
What are our options? We have been variously advised to – 1. tear out the drywall, batting, vapor barrier, and reinsulate with batting with the vapor barrier on the drywall side; 2. those same steps except insulate with spray in foam; 3. retain current system and add a second vapor barrier on the drywall side of the studs; 4. use a special paint that acts as a vapor barrier.
I would appreciate any assistance before we rip the walls apart.
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Replies
George,
Start by reading this article: Insulating Old Brick Buildings.
After you have read the article, you can post follow-up questions here.
https://www.greenbuildingadvisor.com/blogs/dept/musings/insulating-old-brick-buildings
The safest approach is to wrap the bricks in insulation on the outside. This is done all the time in Europe, and it's where EIFS came from. That's the safest approach, and it will make the building substantially more comfortable and energy efficient too, since the thermal mass of the bricks will be on the inside, sheltered by the insulation rather than on the outside, exposed to the elements. Even face-sealed EIFS is safe because the brick structure is warm and not moisture-sensitive the way wood is, but face-sealed EIFS is even safer if you apply a vapor-permeable WRB layer over the bricks, since there may be moisture-sensitive floor joists embedded in exterior brick walls and all things considered, it's better to keep your structure drier if you can. The typical objection to this approach is that it hides the brick facade, which may be characterful and beautiful. But if done tastefully, the new facade can be equally beautiful in a new way. If the brick facade is ugly or deteriorating already, this approach may be a no-brainer.
Thank you for your prompt response. I had read your article previously and, have now reread it, I wish that I had read it prior to the initial insulation.
I think that the exterior insulation is not an option. The closed cell spray foam was proposed by a local insulation company and probably will be our choice. Should we stay at a lower R-level? R-10 seemed to be suggested in a couple articles, what is the trade-off between higher R value? Was the placement of a second vapor barrier, perhaps sandwiched between our current drywall and new drywall a non-starter?
George,
As I noted in my article, there are no easy answers to your questions. You need an experienced consultant to visit your site and make recommendations. If you are confident in your expertise, you can make your own assessment -- but remember, the wrong details can destroy your building.
1. Soft brick is more vulnerable to freeze / thaw damage than hard brick. Your bricks are soft.
2. The potential for damage is greater in climates with freezing weather than in warm climates. Iowa has freezing weather.
3. The potential for damage is greater if the building has stingy roof overhangs than if the building has generous roof overhangs (because damp bricks are more susceptible to damage than dry bricks). Do your bricks ever get wet when it rains?
4. The potential for damage is greater when the building has lots of interior insulation than when the amount of interior insulation is less. Thin insulation is safer than thick insulation.
Good luck.