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Insulating Brick Masonry from the Interior

scottbellner | Posted in Energy Efficiency and Durability on

Interior insulation load bearing brick residence – Detail Question

We are performing a gut rehab on a load bearing brick home in Northern Michigan.
This will be our second masonry home gut rehab and I am a mechanical engineer by trade so you can speak technically.

We will be insulating on the interior, which I know is difficult to pull off well.
I am into WUFI and will start load calcs on Trane Trace or Carrier HAP soon.

As I consider our interior insulation details what are thoughts related to coating the interior of the brick with something like this in lieu of using a spray foam layer (spray & batt) to eliminate air infiltration?

In an ideal world, this would seem to eliminate air infiltration, while also allowing for vapor to pass if needed, but most importantly a healthier insulation (non spray foam) could then be applied to the interior.

If anyone has thoughts on the best load and HVAC design software I would appreciate that too as I have not had to perform those calcs in 5-10 years.

Thanks in advance.

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  1. Expert Member
    Michael Maines | | #1

    That product is listed as >12 perms, which is pretty vapor-open; I'd be concerned about how much moisture would make its way in from the building interior in cold months. I'd feel more comfortable with a variable permeance membrane such as Siga Majrex or Pro Clima Intello which will keep more moisture out but still allow some inward drying. But I don't have direct experience with this situation or even modeling it so this is partly a bump for someone who might have more information for you.

    Here are a few resources for heat load software discussions:

  2. Expert Member
    Akos | | #2

    A fluid applied WRB on the interior can work, it is one of the recommended solutions here (Fig 11):

    Note that the insulation has to be higher density and tight against the brick to avoid convection.

    No matter how you insulation, with brick you always have to watch your overall R value you add as it can make the brick much colder which can lead to spalling if you have softer bricks.

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