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Partial brick veneer

whiteroses | Posted in GBA Pro Help on

A question remains regarding insulating the 3/4 brick front (one wythe veneer) of my 1960 ranch in zone 5/6a.

This is a follow up to:

The home is sideways on a narrow portion of the lot. The 3/4 brick front is on the southern exposure, which consists of (from west to east) the family room, a walk-in closet, the kitchen, the main entry door and closet.

Think relentless sun exposure. There is no space to plant shade trees, unless the sidewalk is moved, which isn’t in the budget.

The family room appears to have been an option – the other option was a two-car garage. This room and closet is built on a slab. There are forced air runs in the slab, but no return. The rest of the home sits on a full basement.

There is about 16″ of soffit overhang which somewhat protects the upper part of the brick wall and window/door openings.

The existing wall is:

one layer of brick
two 1/2″ layers of fiberboard as sheathing
kraft faced fiberglass insulation (very, very thin)

The brick seems to be laid on concrete. I could find no weep holes. The mortar is very soft. The bottom row of brick is covered with sand in a one-foot wide strip along the sidewalk.

At the top is an 8″ trim board covered with aluminum trim.

The plan was to dense pack all the walls and add 1.5″ reclaimed polyiso on the non-brick walls, under new vinyl siding.

But what to do here? Will just dense packing the walls behind the brick create a moisture problem? Would spray foam be a better choice here? What other options would you suggest? A dehumidifier in this room?

I’ve been reading whatever I can find here on brick veneer, but it’s difficult to pick out the information that applies to this situation.

Thanks again for your help.

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  1. GBA Editor
    Martin Holladay | | #1

    J Heckmann,
    You didn't tell us your location or climate. But after I looked at some of your earlier questions, it seems that you live near Rochester, NY (climate zone 5).

    Brick veneer over fiberboard sheathing is a bad combination, because the sheathing doesn't stop inward solar vapor drive. With this type of wall assembly, you have to make sure that your exterior walls don't have interior polyethylene -- especially if your home is air conditioned. For more information on inward solar vapor drive, see When Sunshine Drives Moisture Into Walls.

    If you are able to open up your walls from the interior, closed-cell spray foam would be a better choice than cellulose insulation.

  2. whiteroses | | #2

    Thanks - zone is in first paragraph - I did read about inward solar vapor drive at that link. That article is what prompted the question here, also this quote:

    It is significant to note that the mold and decay problems only occur where
    a permeable exterior sheathing called fiberboard has been installed. The
    problems do not occur where a foam sheathing, plywood or OSB has
    been installed. The reason for this is that the foam sheathing, plywood
    and OSB are less permeable than the fiberboard and therefore does not
    allow as much inward migration of water vapor diffusion from the brick
    veneer moisture reservoir.

    There is no polyethylene sheeting in the walls, no wallpaper, nothing hung on the wall. Due to the age of the home, there may be oil paint on the wall.

    However, in the kitchen there are NEW cabinets installed on the wall. No, I'm not going to deconstruct a brand new kitchen.

    So it would seem the only choice at this point is to do nothing on these brick veneer walls, put up with a couple of cold rooms and a cold kitchen counter, and start saving for (even more) repair work in the future. Possibly check the top vent, look into a pergola or something to reduce rainfall on the brick exterior.

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