Traditional drywall consists of 5/8″ gypsum board (e.g. sheetrock) screwed to the studs. Drywall contractor applies tape to the seams between sheetrock boards, and coat joint compound over the seams and fasteners. If the final finish is to be a flat paint, a Level 4 finish is recommended, which involves the application of a couple of separate coats of joint compound (a mixture of water, limestone, perlite, talc, mica, and lots of other chemicals) over all flat joints, and fastener heads. Level 5 is the highest-quality finish possible on regular drywall achieved by applying a skim coat of joint compound over the entire sheetrock surface to conceal slight differences in texture. Level 5 drywall finish produces a monolithic surface ideal for painting under different light conditions suitable for sheen and enamel paint finish. The biggest drawback of drywall is the amount of dust it produces with each sanding session.
Veneer Plaster
Veneer plaster finish is an alternative to drywall. Instead of a sheetrock, plasterer applies the very wet plaster (composition of plaster of Paris and sand with lots of water) over 5/8″ blue board, first over the seams and fasteners, and then skims 1/16′ – 1/8″ coat over the whole surface. Plaster bonds chemically with the paper in blueboard, which is engineered to create a tight bond with the plaster compound using a multi-ply paper where the outer ply absorbs the water in plaster coat while the inner ply protects the gypsum core with its water resistance, creating a surface that is much harder than regular drywall. In terms of compressive strength, veneer plaster finish is about 10 times stronger than a drywall, making it less likely to get dents and dings, and expose popped screws. In contrast to drywall, veneer plaster does not require sanding. Plus plaster is a vapor barrier ideal for bathrooms and kitchens, provides a better sound barrier than drywall and is more fire resistant.
Our architects Theodore + Theodore convinced us to go with unpainted veneer plaster instead of a drywall finish. Although the veneer plaster estimate had a substantial premium over Level 5 drywall finish, savings in forgoing the paint actually made the plaster option more economical. In contrast to the monolithic painted drywall look, the veneer plaster has a hard silky handmade finish with a natural off-white color. Another advantage is that plaster can be applied directly to concrete over a base coat, which came in handy in the Lily Pond House basement wall.
Spang Builders selected Amabile Brothers as the plastering subcontractor. Amabile Brothers is a second generation family business, who learned the craft from their father, who in turn learned the craft from his dad by plastering closets when he was six years old. Our plasterer used Uni-Kal veneer plaster that dries in about 2 days. Plastering is an artistic skill honed over years of practice that involves packing and polishing the plaster to a mirror finish with a steel trowel, and running a clean felt brush over the plaster to take the sheen out. There is about half an hour window when plaster can be applied to a surface as the chemical reaction that occurs when the plaster is mixed with water causes it to crystallize quickly.
Plaster is becoming popular in green building practice. There is a funded KickStarter project – The Art and Science of Natural Plaster that aims to produce an educational documentary on the use of natural plasters in architecture. Earthen plaster (a mixture of clay, sand and fiber) is another environmentally friendly option. American Clay sells earthen plaster in dozens of different colors. If you are DIY capable, there are lots of recipes for making plaster in Clay Culture.
Lily Pond House 