Drywall Cost Estimator

Drywall estimating starts from net wall area. Gross area is perimeter times ceiling height times the number of rooms, from which roughly 10 percent is deducted for door and window openings, and a further 10 percent is added back as cutting waste before dividing by sheet area. A 4 by 8 sheet covers 32 square feet, a 4 by 12 sheet covers 48, and longer sheets are preferred on tall or wide walls because they reduce the number of butt joints, which are the hardest joints to finish flat. Board selection drives material price: standard half-inch board is the baseline, moisture-resistant board is used behind tile and in bathrooms, five-eighths Type X carries a glass-fiber core for fire-rated assemblies, and laminated acoustic panels cost roughly twice standard board. All of these are manufactured to ASTM C1396. Labor is usually split into hanging and finishing because the two are priced differently and often performed by different crews. Hanging is relatively fixed per square foot, while finishing scales with the level of finish specified. The industry uses a six-step scale, Levels 0 through 5, defined in the GA-214 document published jointly by the Gypsum Association and the painting and wall-and-ceiling contractor associations. Level 3 suits heavy texture, Level 4 is the normal specification for flat paint and light texture, and Level 5 requires a skim coat over the entire surface and is specified where gloss paint or severe critical lighting would reveal joint photographing. Consumables scale predictably: about one roll of tape per 300 square feet and one bucket of joint compound per 100 square feet. The estimate excludes framing, insulation, texture spray, primer and paint, and it assumes reasonable site access.

Before gypsum board, interior walls were built as lath and plaster, a slow wet trade requiring three coats and weeks of drying. The substitute originated with Augustine Sackett, who in 1894 patented a board made by pressing plaster between layers of paper, produced as Sackett Board. United States Gypsum acquired the process in 1909, refined it into a single-layer panel with wrapped edges, and marketed it under the Sheetrock trademark from 1917. Adoption was slow while skilled plasterers remained plentiful, but material and labor shortages during the world wars, followed by the enormous postwar housing expansion in North America, made a dry panel that could be hung and finished in days rather than weeks decisively cheaper. As the product became universal, the arguments moved to finish quality, and those disputes drove the standards that estimating now depends on. Painters blamed drywall finishers for joints visible under sidelighting while finishers argued the specification had never asked for that quality. The Gypsum Association, working with the Association of the Wall and Ceiling Industry, the Ceilings and Interior Systems Construction Association and the Painting and Decorating Contractors of America, published the Recommended Levels of Gypsum Board Finish, designated GA-214, around 1990 to settle the question by defining measurable levels of finish. Parallel developments extended the product line: Type X fire-rated board with glass fibers was developed to meet the hourly ratings tested under ASTM E119, and moisture-resistant and mold-resistant boards followed as building science addressed wall cavity moisture.