Mortar acts like a glue to hold masonry units together, transforming individual bricks and concrete blocks into solid walls, floors, patios and foundations. The most common mortar mixes are identified by a letter, which indicates the specific ratio of portland cement, lime and sand used to make each variety. While Type S and Type N mortar are forms of all-purpose mortar, they differ slightly in their properties and recommended uses.
Type N mortar offers medium compressive strength, making it appropriate for most normal brickwork applications. It consists of 1 part portland cement, 1 part lime and 6 parts sand. Use this mortar for the majority of exterior, above-grade applications, such as the veneer or chimney of a residence.
Type S mortar offers higher compressive strength than Type N mixes, making it appropriate in cases where you need a stronger mortar. Choose Type S in below-grade applications or projects subject to seismic activity or high wind. This mixture consists of 2 parts portland cement, 1 part lime and 9 parts sand.