Mortar Types

Type M

Has a high compressive strength and good durability. It is used for unreinforced underground masonry.

Type N

Medium-strength, general use mortar. It is used for exposed, above ground masonry.

Type K

Very low strength and should only be used for interior applications when strength is not a concern.

Type S

High-strength mortar. Compressive strength is not as high as type M, it has a stronger bond and greater lateral strength. It also has the greatest tensile strength of any mortar. Used for reinforced, unreinforced masonry subject to bending, and in situations where mortar is the only connection between face brick and backing brick.

Type O

Low-strength mortar used for interior, non-bearing masonry. This type should not be used with masonry exposed to freezing temperature.