Westlake Royal Building Products

Yes, for exterior applications use only cement board that complies with ASTM C1325. For interior installations, any ½” or 5/8″ cement board product is acceptable. Always bond the stone with polymer modified mortar compliant with ANSI A118.4 or ANSI A118.15. Do not use conventional Type S mortar for bonding stone to cement board. Please consult cement board manufacturer for board installation, tape, anchor and other instructions.

Applying a sealer or coating that is not capable of “breathing” will jeopardize the long-term health of the wall structure. Moisture that can collect in the wall system must be able to dry out through the wall covering. However, the application of a silane or siloxane water repellent can be used to slow the water absorption into the stone while rendering the color, texture and breathability of the stone veneer unaffected. For the health and safety of the application, select a water-based (rather than a solvent-based) silane or siloxane repellent. Follow manufacturer recommendations for dilution, appliacation, and re-application.  Test in an inconspicious area before applying to the wall.

Adhered stone veneer is designed and intended as a wall covering. Using adhered stone veneer on a horizontally oriented fashion should only be done as an engineered system. Do not use adhered stone veneer as a paver or a wall cap. Do not install adhered stone in a situation in which continuous or frequent exposure to water is possible such as pool or Jacuzzi copings or surrounds. Adhered stone veneer is not intended to be installed on stair risers where deicing salts or snow shovels can damage the stone façade.

Manufactured stone provides the realism of natural stone at an installed cost of a fraction of natural stone. Because manufactured stone is made of lightweight material, it is classified as an adhered veneer as does not require a footing or mechanical support for installation.

Type S mortar complying with ASTM C270 has been commonly used to bond manufactured veneer products. For additional bond strength and other benefits the use of a Modified Mortar meeting ANSI A118.4 and/or ANSI A118.15 can be used. For applications over cement board a Modified Mortar must be used. Building codes are changing and in areas that have adopted the 2024 building code the use of Modified Mortars are required and the only option for setting mortar.

States and local municipalities that have adopted the 2018 International Building Code (IBC) or International Residential Code (IRC) have the requirement for a manufactured stone veneer to meet ASTM C1670 in the Adhered Masonry Veneer section of the code.

The building code requires a clearance between the stone veneer and the grade or ground level.  In most cases building code requires a 4" clearance to grade, 2" clearance to a paved surface, and 1/2" clearance if the paved surface is part of the foundation the wall is on and all concerns with water, de-icing, and possible damage issues are addressed. There are several reasons for this and most of these reasons involve protection of the wall, not the stone! Behind the stone veneer is a drainage plane that was created when the weather-resistive barrier was installed. The purpose of this plane is to collect and direct any water that squeaks behind the wall façade downward and out the base of the wall. If the base of the veneer wall is at or below grade, proper drainage will be impaired. Secondly, water that pools or collects at the wall base can rise into the wall through capillary action and enter the structure. Thirdly, if the veneer is in contact with vegetation (grass, plants, etc.), growth into the wall is possible. Also, bugs and insects, including termites, will find it convenient to enter the wall system when the wall is in direct contact with earth. Finally, the stone is not designed to be continually wet or subject to the harsh chemicals found in soils.

Masonry adds resilience, beauty and a sense of permanence to any project and is one of the most prolific building materials. The standardization of ASTM C1670 solidifies MSV’s presence and viability in today’s building ecosystem. Builders and contractors will be looking to product manufacturers more and more to demonstrate adherence to the standard at each of their manufacturing facilities which then establishes confidence in the long-term use and durability of the MSV products themselves.