Question

Of the four types of mortar — M, S, N, and O — M and S are usually used for load-bearing masonry and new construction where high strength is required. Type O is weak and usually only used in interiors. What is type N commonly used for?

Answer

Type N mortar is usually used for restoration or repointing work because it tends to match the strength and properties of older mortars. Existing masonry can be damaged by using incompatible or stronger mortar mixes when repointing.