Type S Mortar
When installing pavers in areas such as walkways and driveways where there will be heavy loads or high traffic, type S mortar is best to use for installing the pavers. Type S mortar is one of the most resilient mortars and will dry to a hard, crack resistant finish. Type S mortar can withstand greater loads than almost all other mortar without failing or crumbling. Additionally, type S mortar is waterproof and will shed water and withstand pooling water conditions that remain on the surface of the pavers. Type S mortar will stain your pavers, however, so sealing the paver surface prior to installation is recommended.
Type N Mortar
Type N mortar is recommended for exterior paver installations, such as walkways and patios. This mortar is cheaper than type S and should be used where there is no chance of heavy loads or prolonged exposure to water. Type S mortar is somewhat brittle if exposed to excessive heat, such as direct sunlight, for more than 6 hours. However, this mortar will not stain your pavers during application and is more cost-effective when high-strength installations are not required.
Interior Thinset Mortar
Interior thinset mortar is recommended for indoor paver installation. This mortar is flexible and is less likely to break when impacted by large objects such as dishes or furniture. Because house floors routinely move and settle, this mortar is recommended because of its flexibility. Interior thinset mortar has an additional latex additive, which aids in bonding to wood surfaces. Although this mortar is more expensive than the others, it does come in a powder mix that has sand already added.
Exterior Thinset Mortar
Exterior thinset mortar is recommended for outdoor installations where ice may regularly accumulate. Because water may infiltrate the mortar joints of pavers on the exterior, it is likely to freeze in colder conditions, expand and crack the pavers. Exterior thinset mortar is more pliable than all other mortar. It will expand and contract depending on the exterior conditions, preventing cracking of pavers. In addition, exterior thinset mortar is waterproof, and it will shed rather than absorb water and ice.