Type 1 is a professional-grade, traditional, nonflammable, organic adhesive for setting impervious, vitreous, semivitreous and nonvitreous tile over gypsum drywall (walls only), cement board, exterior-grade plywood, concrete and masonry block. This adhesive is used for interior applications only. Type 1 meets or exceeds ANSI A136.1, Type 1 requirements.