[Greenbuilding] Insulating brick unframed envelopes

[Norbert Senf]

Around here (Ottawa, Ontario) pre 1920 houses are all soft clay brick,
lime/sand mortar, thin joints. The bricks are quite permeable. They do not
withstand freeze thaw. However, they are still intact because sufficient
attention was paid to overhangs, flashings, etc, that you almost never had
the situation of a completely saturated brick freezing. The wall is very
permeable to moisture. By 1950 everything was portland based mortar
(impermeable) and a large variety of bricks, including hard non-permeable
ones - for that type it would be wise to characterize the masonry first, so
that you can get an idea of its moisture permeability.

On Mon, Mar 16, 2015 at 12:56 AM, Jason Holstine <jason at amicusgreen.com>
wrote:

>
> We are trying to tackle a holy grail—insulating old brick-front homes
> without covering or redoing the exterior brick.
> Buildings are vintage 1890-1950. Typically brick with plaster interior and
> that’s about it. These are often rowhouses with rear extensions (not
> bricked), so it’s typical that we’re only talking about doing 1 or 2 sides
> of the building.
>
> It’s in the DC/MD region in the heart of mixed-humidness, but it’s
> noteworthy our winters are getting harsher. This is a concern I have.
>
> We’d like to avoid framing out the walls to minimize the loss of floor
> space. So, we’re thinking about air sealing then insulating on the interior
> with 2” foam board or mineral wool 2” board (R8). In either case, the plan
> is to attach sleepers and drywall right on top. We figure this isn’t ideal
> but is certainly an improvement.
>
> A main concern is that insulating the brick walls may lead to brick
> damage, but how much of this is germane only to cold climates?
>
> How nuts is this plan?
> If we go foam board, how imperative is closed-cell or open-cell?
> If not using closed-cell foam board, should we apply a vapor-smart weather
> barrier on the inside of the brick first?
>
> Bonus question: Any risk of also insulating bricked party walls that show
> leakage?
>
> Thanks,
>
>
> Jason Holstine
>
>
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-- 
Norbert Senf
Masonry Stove Builders
25 Brouse Road, RR 5
Shawville Québec J0X 2Y0
819.647.5092
www.heatkit.com
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