Our project team is attempting the LEED 2009 for Healthcare Low Emitting Materials credit for Group 1: Interior Adhesives and Sealants and for Group 3: Flooring. This credit requires that chemicals on the Proposition 65 list cannot be present at more than 1% of the adhesive’s or sealant’s total mass. The chemical and detail, "Silica, crystalline (airborne particles of respirable size)," appear on Proposition 65 list. Crystalline silica is a basic component of soil, sand, and granite; other trade names for silica are sand, masonry sand, fill sand, golf course sand, industrial sand, and construction sand. As majority of healthcare projects do, this project requires use of both grout and thinset products.
Though the products our team selected are compliant with the Low-VOC portion of the credit, they do contain crystalline silica over the 1% threshold, as sand is a main component of these types of products. We have worked with multiple manufactures and suppliers to find grout and thinset products without silica and have had no success. We have also requested manufactures quantify if the size of the particles are of respirable size and confirming the size of particles to this standard has been difficult. As the intent of the credit is to, "Reduce the quantity of indoor air contaminants that are odorous, irritating and/or harmful to the comfort and wellbeing of installers and occupants”, our team worked to identify if the risks are present to installers and occupants. Manufactures have confirmed that the crystalline silica will be completely encapsulated in a hardened, non-friable state after installation. This would eliminate all hazards and risks of the chemical for future occupants. We have also confirmed that, if the products are installed per manufacturer's recommendations, installers will be protected from the chemicals and will face no risk of inhalation. It is a common best practice that our construction management team ensures all materials are installed according to manufacturer recommendations. On this project we are also implementing a detailed Construction IAQ Management Plan that ensures nearby workers would be protected, as well. These efforts confirm that there will be no risk to installers or other workers.
If the grout and thinset products are installed per manufacturer’s recommendations and, therefore, eliminate the risk of crystalline silica (sand) harming installers and occupants, can the team conclude that these products meet the intent of the credit and comply with Low Emitting Materials Group 1: Adhesives and Sealants and, therefore, Group 3: Flooring?
The project team is asking whether grout and thinset products containing more than 1% silica meet the intent of LEED 2009 for Healthcare EQ Credit Low Emitting Materials, Group 1: Adhesives and Sealants. Yes, when installed according to the manufacturer’s recommendations for worker protection, the proposed grout and thinset products meet the intent of the credit. The California Proposition 65 list used as hazard screening criteria for this credit includes “Silica, crystalline (airborne particles of respirable size)“. Since the silica used in thinset and grout mix is not respirable once the products are mixed and set, the grout and thinset products meet the intent of the credit. This exception is unique to silica and does not set precedent for other materials listed on the Proposition 65 list.
Related Addenda (Corrections & Interpretations)