I've read that one should use a special type of mortar with old brick houses because they expand more - portland mortar vs soft lime.
The recommendation from the NY Landmarks Commission states:
Use a soft, lime-rich mortar that will be elastic and allow for movement, which will help prevent spalling and breakage of historic brick due to expansion caused by water absorption.
I might possibly need to submit a permit to do this small repair.
If I need to repair some small sections of mortar to prevent water and ice getting in - should I use commercial regular mortar repair tubes or should I get an acrylic-based or some other special mortar repair product? Is the section small enough that I don't need to worry about matching expansion rates and sand color? It looks like this small section was already repaired more recently and doesn't have matching color mortar. Was using the wrong type of mortar the reason it's cracked?
The cracks are not huge - pictures shown below. Could I even use non-sanded grout repair material?
Cracks around mortar at knee level around the 1st-floor main exterior doorway (up a set of stoop stairs)