Which type of mortar is medium-high strength, used where bond and lateral strength are important?

The type of mortar that is considered medium-high strength and is utilized where bond and lateral strength are important is indeed Type S mortar. This mortar type has a compressive strength of about 1,800 psi (pounds per square inch) and contains a mix of Portland cement, lime, and sand, which contributes to its durability and flexibility. Type S mortar is particularly suited for applications where the bond strength to masonry units is critical, such as in load-bearing walls or structures exposed to the elements.

The lateral strength provided by Type S mortar makes it ideal for use in construction projects that require seismic resistance or high wind resistance, enhancing the overall stability of the building. It is commonly recommended for below-grade applications, as well as in structural wall applications, allowing for effective load-bearing capabilities.

This specific combination of features—medium-high strength, excellent bond characteristics, and lateral stability—make Type S an essential choice in the masonry work where both strength and durability are paramount.