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  1. #1
    Join Date
    Oct 2009
    Posts
    8

    Default repointing brick foundation walls

    Hello,

    I recently moved into a house built in the 1920s that has a brick foundation. The mortar between the bricks are in desperate need of repointing. Can I safely use a mortar from a home center, or do I need to mix a lime mortar? I have read that lime mortar was used up until the 1860s, so I am guessing a regular mortar is fine, but I want to be sure.

    thanks!

  2. #2
    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    975

    Default Re: repointing brick foundation walls

    You want a type O mortar. Type K would also be fine, as it's even softer than O. If you err with too soft a mortar, no damage is done. The reverse is not true. You never know with old brick.
    1920's did see the use of high-fired hard brick become widespread. If your brick has a wire-scratched (striated) surface, is perfectly uniform in size, or has crisp sharp corners, it is high-fired brick. In such case you could use a type N or harder mortar but bear in mind that if the existing is softer, you have created the opportunity to begin a crack in the brick. The moisture-handling characteristics of lime vs. portland mortars is very different, as portland mortar is not water permeable and it forces moisture to seek other paths, either through the brick or wherever it can.
    http://www.astm.org/SNEWS/AUGUST_2003/gerweg_aug03.html
    S_M
    Last edited by Sombreuil_mongrel; 05-29-2010 at 11:04 AM. Reason: add link
    Remove not the ancient landmark, which your fathers have set.

  3. #3
    Join Date
    Oct 2009
    Posts
    8

    Default Re: repointing brick foundation walls

    thank you!

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