What kind of mortar do I need to use?

Question

I am going to begin some repairs to the brick foundation walls of my 1890s farm house. Mostly it will be tuck-pointing where mortar has crumbled out, but some of it will be replacing some bricks that have come loose. We have loads of old bricks from a porch foundation wall that crumbled. We pulled & stacked all the old brick and replaced the porch foundation with poured concrete pillars.

I know to chip out any loose mortar so the new stuff has something solid to hold on to, instead of having a firm hold on a loose chunk.

At my local big-box, I've seen type S and type N mortar. Does it matter which type I use for this repair work?

Answer 1

Type S is what you'd want.

Type N is a mortar that fares well above ground, but has a relatively low compressive strength. Most common applications would be things like brick/stone veneers, but it is a pretty good all-around mortar.

Type S is a much stronger (higher compressive strength) mortar and used below grade for things like a masonry foundation or retaining walls. The high compressive strength is needed in below grade due to the forces (soil and water for example) you might see against the foundation.