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huberm
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!

Sombreuil_mongrel
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

huberm
Re: repointing brick foundation walls

thank you!

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