What Kinds of Mortars Are for Shower Walls?
Upon embarking upon a DIY shower project, you must decide which tile or natural stone to use and corresponding grout colors. Shower wall trim and accessories, glass enclosure design and dimensions and other item are on the decision list as well. Before getting to advances choices and options, first consider the basics: DIY shower walls require two mortar types; one for the shower wall underlayment; one for installing the tile itself. Both are vital components to a quality, lasting do-it-yourself shower project.
Use a cement, lime and sand mixture -- called a wall float mix -- for constructing shower wall substrates. A substrate is the construction industry term for an installation surface area. Purchase a wall float mortar mix or create a 3/1/1/ mixture -- 3 shovels of sand, 1 lime and 1 Portland cement -- in a wheelbarrow. Use fine-grain stucco or masonry sand, mixing all 3 parts. Mix the contents dry first, adding cool water slowly. Mix the contents with a masonry hoe or shovel. Remix again 10 minutes after the initial mixing. Cover the wall float mortar mix or keep it in a cool, shaded location.
Thinset mortar is the industry standard tile shower wall adhesive. Add a liquid acrylic additive to non-modified, basic thinset mortar. For extra tile bond and longevity, use a special latex-modified thinset mortar. Use special thick or medium bed thinset mortars for installing large natural stone. Use thinset mortar with flex properties for remodeled walls. Use proprietary glass tile or glass mosaic thinset mortar for glass products. Thinset mortars are available in tile supply stores, building product warehouses and home improvement stores.
Shower Wall Preparation
Cover wall framing (sheathing or 2-by-4 walls) with either a heavy felt roofing paper or heavy moisture proof plastic sheeting. Use a hand stapler to affix the plastic or paper to the walls. Seal any penetrations (such as staple holes or tears) with silicone caulking. Nail or staple chicken wire over the moisture barrier. Use a hawk and float for applying the wall float mix to the chicken wire. Install an initial thin mortar layer, or so-called scratch coat. Allow 24 hours for proper curing. Apply the float wall mortar mix over the scratch coat. Plumb the walls with a level and straight edge.
Do not add or subtract lime from the 3/1/1 wall float mixture. Doing so will compromise the substrate's strength or produce a situation where lime or cement bleeds out of the shower tile grout joint lines. Also, verify that mortar sand is clean and debris-free and specifically designed for stucco/tile/masonry purposes. Do not use garden or beach sand as they both may contain salts and minerals that would compromise substrate efficacy.