As the popularity and use of Natural Thin Stone grows, installation research and finds are producing enhanced standards that are generating better longer-lasting installations at reduced costs.
Historically, the minimum acceptable standards for installing Natural Thin Stone have long been the following:
1. Apply sheathing over the studies. This sheathing can be exterior OSB, plywood, exterior grade drywall, wallboard or cementitious board.
2. Staple the building paper to the sheathing. Attach the building paper in horizontal strips. Start at the bottom and overlap 2 "(like shingles) Overlap the vertical joints by at least 6". If using flashing or support brackets (anchors), install them before proceeding to the next step.
3. Screw, staple or nail the metal lath to the studies with a maximum horizontal spacing of 16 "oc Overlap the metal lath at least 1" for horizontal and vertical joints. At corners, overlap the vertical joints at least 16 "around the corner to avoid corner cracking. Use barbed galvanized nails at 6" oc vertically for exterior work or steel wire furring nails at 4 "oc for interior work." Minimum nail penetration is 1 " into the studies. For steel studies, the lath must be anchored with corrosion resistant screws that have a minimum shank diameter of 0.190 ".
4. Apply a scratch coat of mortar that is 3/8 "to 1/2" thick over and embedding into the metal lath. Use a toothed scraper, notched trowel or small piece of lath to lightly rake horizontal grooves in the scratch coat. Allow the scratch coat to cure for a minimum of 24 hours.
Across the United States, depending on the geography, the climate, the moisture level, Enhanced Installation Techniques and Systems have been developed that offer superior performance. One of those approaches is described below.
Enhanced System for use over Wood or Steel Stud Substrate
In this application, the Lath and Scratch Coat is replaced with Cement Backer Board and Roller-Grade, Flexible Waterproofing Membrane. Using the Cement Backer Board eliminates installer errors that can occur by scratching the initial coat of mortar too deep. If this overly deep scratch occurs, moisture can penetrate the coat and lead to corrosion of the lath and completely complete installation system failure. By using the Cement Backer Board and the Roller-Grade Flexible Waterproofing Membrane, this lath and scratch-coat system weakness is eliminated.
Similar to thin set tile installations, movement joints are also used every 8-10 feet. The below graphic substances Laticrete's approach using their HydroBan Acrylic Waterproofing Membrane and their 255 MultiMax Thin Set Mortar. This type of system not only offers superior performance, but can reduce total installation costs by 10-30%. Other enhanced products are listed below.
These products have been tested for use in most climates in the United States and proven to provide last protection. Many include warranties as well.
Cement Backer Board
· PermaBase by National Gypsum
Waterproofing Membrane
· HydroBan by Laticrete
· Mapelastic Smart by Mapei
· Sure-Coat by ProSpec
Mortar
· 255 MultiMax by Laticrete
· Ganirapid Mortar by Mapei
· StayFlex 590 by Prospec
Other Applications
When applying Natural Thin Stone directly to Concrete, Concrete Block or Existing Masonry, adding a Roller-Grade, Flexible Waterproofing Membrane will significantly enhance the soundness of the installation.
Overall these Enhanced Natural Thin Stone Installation Systems improve the quality, longevity and the cost of using the superior product of natural thin stone veneer.