Grout is used to fill the gaps between tiles after they have been set in place. There are multiple types of tile grout including cementitous, epoxy grout, 100% solids epoxy, and single component grout (which can be urethane or siliconized acrylic). According to the Tile Council of North America, cementitous-based grout is the most common and is therefore the focus of this CP. These products are delivered to the job site as a dry powder and are often polymer-modified to improve the performance of the grout. These products meet or exceed the performance standards of ANSI A118.6. Some products advertise additional performance improvement by mixing with a latex admix on site instead of water, which can result in a grout that meets ANSI A118.7 standard requirements. Admixes may contain problematic alkylphenol ethoxylate surfactants. See the All Contents for additional information on potential content of latex admixes. Cementitious grout can be sanded where the primary filler is sand (for joints from 1/8" to 1/2") or unsanded where the primary filler is a finer powder, often calcium carbonate (for joints that are 1/8" or less and with tiles that may scratch easily). This CP covers a standard polymer-modified, sanded cementitious grout. These products are advertised for use in interior and exterior applications, for commercial or residential, floors or walls, wet and dry areas. Grout products that are "rapid set" are outside the scope of this CP, but some content information for these products is included in the All Contents. 

Many, but not all grout products advertise antimicrobial properties. These antimicrobial properties come from biocides that are present in the dry grout mix. In other cases, biocides may be included in the optional latex admixes. The specific biocide(s) used is not commonly disclosed but may introduce various hazards. Some products may contain pre- or post-consumer recycled content such as fly ash or ground glass, but this was not found to be common. Phosphogysum was identified in a couple of products. The US EPA bans the use of phosphogypsum, a byproduct of the production of some fertilizers, in almost all applications because it can be radioactive, however, phosphogypsum may still be present in imported products. 

Many cementitous grout products recommend the use of a sealer to prevent staining. Sealers can introduce additional hazardous content such as PFAS. More information on the content of grout sealers can be found here and here. Stain-repellent mixes that may contain PFAS can also be added to the grout prior to application.