Key Points

• The aluminum panel layer of StonePly stone panels prevents moisture from passing through the panel
• Most building stones used in StonePly stone panels need no water repellent
• Some stone panels made with softer stones may benefit from a water repellent

StonePly Stone Panels Are Impermeable to Moisture

StonePly stone panels will not allow moisture to pass through them. The epoxied aluminum backing provides a continuous solid barrier behind each panel. This helps keep moisture out of the building. Granites and the majority of marbles have a very low absorption rate and need no water repellent. Other types of stone panels, such as those made with limestone or the softer marbles, may benefit from repellents.

Do I Need to Use Water Repellent?

In some cases, the designer may want a water repellent treatment for cosmetic reasons. Some masonry groups do not approve of the use of water repellents on natural stone panels.

• Granite stone panels do not typically need any repellent
• Marble stone panels may benefit from a repellent if the marble selected has a high absorption rating
• Softer limestone panels may also benefit from a water repellent
• Onyx stone panels should receive an application of water repellent as onyx is typically not for exterior use
  

Some of these treatments lend a good amount of cosmetic protection to stone panels. Stone panels made from a stone with a high absorption rate can potentially be made water repellent for several years. This will also keep the stone panels looking cleaner and newer for an extended period of time. Manufacturers of water repellent materials should be able to produce a performance statement for their materials. An actual piece of the stone panel type selected should be tested for possible color change.

Factory-Applied Repellent

Water repellents can be factory-applied if requested. There is some value to having the stone panels arrive on site ready to install and with no further treatment needed.

Field-Applied Repellent

Should you decide to use site-applied water repellent on your StonePly stone panels, it is imperative that the manufacturer's instructions be followed. If possible, have a representative from the company on the job site when the treatment is being performed. Make sure the person applying the water repellent and the manufacturer's representative agree that the substrate is the proper condition, the weather is right, and the tools being used are correct. Obtain a statement of service life for the materials, and make sure you keep the company's contact information in case something goes wrong.

• The repellent must be compatible with the sealant
• Verify the suggested flow rate and coverage
  
• Stone panels should be clean, dust-free, and totally dry
  
• Do not apply repellents over stone panels with stains or discolored areas
• The applier should protect surrounding shrubbery, walkways, traffic areas, and any other nearby surfaces that are not being treated

Water repellents are labor-sensitive; successful applications depend upon good workmanship. StonePly recommends against using any water repellent products that are incompatible with joint sealants, plastics, and finishes.