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Community and Q&A

Parging a spalling brick wall

Mary Farrah | Posted in General Questions on

I just had the entire exterior back wall of my house parged. The bricks were so old and damaged that they were literally crumbling and turning to sand at the touch. Initially I was going to have them pointed/repaired, but the mason advised me the bricks were too soft at this point to do that. After all of this happened, I noticed a different kind of brick used on the front of my house was taking in water and damaging the plaster interior walls. This was after two weeks of periphery rain from hurricanes. To make a long story short, I did research, found this site, and read articles for hours and hours. What a great resource this site is!!! Now I understand that there are different kinds of mortar and brick, and my bricks are the old sort (circa 1915) that require lime based mortar. I checked with the mason to see what he used, and he used N type mortar with a psi of 750 that’s better for soft bricks like mine. I checked and it still has cement in it. Am I worse off for having this on my old, spalling bricks? Please advise.


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  1. GBA Editor
    Martin Holladay | | #1

    Your problem probably can't be answered without a site visit. The first question is, what is causing the spalling of the bricks?

    There are many possible reasons for brick deterioration. The most common reasons are poor water management (insufficient overhangs, insufficient drip-edges, flashing problems, broken conductor pipes, bad details) and a bad insulation job (choosing an insulation method that makes the bricks vulnerable to freeze/thaw damage).

    If you don't feel you have the knowledge to assess the existing water-management details and insulation details, you may have to hire a consultant.

  2. Michael Chandler | | #2

    Can you post some images from before the parging was done? It may help to determine if the water is wicking up from the ground or being absorbed from wind-blown rain or coming in through bad flashings and roof detailing. In any event I applaud your mason's choice of type N as opposed to type S which is what most would have used. Sounds like he is more aware and on your side. Still you need to get a better understanding of where the moisture is coming from that is causing the spalling.

  3. Mary Farrah | | #3

    Hi Michael,
    I suspect the water damage could be all of the above. The areas closest to the ground were in extremely bad condition (worse than the photos I've attached), but I didn't have any photos of that area. There was also damage by the roof and around windows in the back (see photo). It's pre-parging, but you'll see some minor repairs. The 5' parapet on the roof is in terrible condition and leaks. The other photo is of the bricks under the front porch, which are as close an approximation to the area by the walk out basement as I have.

    Yes, the mason I used is actually my cousin's husband so I don't think he'd purposely do wrong by me. Very relieved that type N is okay.
    Thanks for that.


  4. James Morgan | | #4

    The photo of the upper wall indicates you have a significant structural problem as well as the spalling of the arch brickwork. The brick pier on the left of the right hand window is too narrow to resist the lateral load of the arch above, hence the vertical crack at its base through several courses. There have obviously been some attempts made at fixing this problem including some haphazard replacement of the brick and repointing of the cracks but unless these have included some provision for tying the top and bottom of the pier through to the solid wall beyond it's only a matter of time before the cracks re-open, readmitting moisture to the interior of the wall. A thin parge coat will do nothing to prevent this. There appears to be no room for insulation on the interior of the wall beside the window - if there's room at the side where the wall abuts the left hand window (can't quite see from the angle of your photograph), covering the exterior of the brick with insulation and siding would be your best bet to both insulate and weatherproof. If there's no room to do that a coat of traditional stucco, not parging, over properly secured metal mesh would at least keep the water out and stabilize the corner.

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