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.
Last edited by Sombreuil_mongrel; 05-29-2010 at 12:04 PM.
Reason: add link
Remove not the ancient landmark, which your fathers have set.