Just how low the VOC level needs to be for a given product to qualify for inclusion in GreenSpec depends on the product category. For most products, we require certification to California’s health-based emissions standard, CDPH Std Method v1.1 standard (also referred to as California Section 01350), which tests a product’s resultant VOC concentrations in the space after a given period of time. For wet-applied products like paints, caulks, and adhesives, we still also look for VOC content instead of, or in addition to, verified low emissions; this is because emissions testing doesn’t adequately test initial offgassing, and VOC content is currently the only widely available proxy.
Mapei offers low-VOC mortars for a wide range of applications. Many of the company’s products meet California’s Collaborative for High Performance Schools (CHPS) emissions criteria, including Kerabond, Keralastic, Granirapid, and Ultraflex LFT thin-set mortars.
Thin-set tiling is installed using a layer of adhesives 3/16"-thick or less, typically either mastic or thin-set mortar. Tile mastics are pre-mixed organic products typically used with ceramic tiles—they can discolor porous porcelain or marble tiles. Mastics should be used in applications such as kitchen walls where they will not be exposed to moisture. (There are type I and type II mastics, and while manufacturers claim that type II can be used in high-moisture conditions, but some professionals recommend against the practice due to the potential for mold and loss of bond strength.) Mastics are easy to apply and hold well in vertical applications, but do not allow tiles to be adjusted if there are substrate imperfections.
Thin-set (dry set or dry bond) mortars contain portland cement and fine sand as aggregate along with additives that help maintain moisture and consistency. Because they are cementitious, they will not break down in water like mastics. Latex-modified thin-set mortars contain synthetic latex/vinyl acetate to improve flexibility and workability. Thin-set mortars should be used on all flooring and high-moisture applications.
Tile adhesives listed by GreenSpec meet SCAQMD 1168 VOC limits of 65 g/l and do not contain any formaldehyde, antimicrobial compounds, or hazardous airborne pollutants (HAPs). GreenSpec does not list epoxy-based mortars containing bisphenol-A, an endocrine disruptor.
Ratings and Commentary