by Don Vandervort, © HomeTips
When you’re remodeling, a clear understanding of how interior walls are built is essential to a successful outcome. Most houses have wood-frame construction—a wooden framework is clad on the outside by siding and finished on the inside with an interior wall surface material.
Because wall-building materials have evolved over time, the age of a house has a lot to do with the materials and techniques used for cladding its interior walls. Houses built before the 1930s tend to have wood-lath-and- plaster walls. (Plaster is still used in high-end construction.)
After 1930, builders began to use a metal mesh or perforated wallboard as a backing for plaster, in the place of wood lath. In the 1950s, drywall (also called gypsum wallboard or the trade name Sheetrock) began to see widespread use and today covers most new construction.
Drywall panels have a layer of gypsum sandwiched between heavy paper facings. A waterproof type— sometimes called green board—is used in bathrooms and other areas subject to heavy moisture.
Sheet wood paneling was applied to many walls in the 1960s and 1970s, and a variety of wood paneling is still used, primarily as an accent for a study or family room where its warmth and character are desired. Wood paneling is made both in sheets and in individual, interlocking strips. It is glued or invisibly nailed to existing walls or furring strips; furring is always needed when paneling is applied to masonry walls.
Classic wainscoting, which not only gives walls elegance and warmth but also protects the lower portion from wear and tear, is made up of several different pieces of milled hardwoods that are fastened together.
Exterior walls that carry ceiling, roof, or upper-floor loads to the foundation are load bearing or simply “bearing” walls. Internal walls that support joists at mid-span and transfer loads down to foundations are also bearing walls.
Bearing walls usually have perpendicular joists or rafters crossing or resting on top of them and foundations underneath them. Exceptions are the end walls of a gable-roofed house; these usually run parallel to rafters and joists and must bear the weight of extensive wall framing.
Wind and seismic loads, which produce lateral stresses on a house, are managed by tightly interlocking framing members. Plywood sheathing or wood or metal cross bracing interconnects framing members, creating a sturdy triangular form and—with foundation bolts—lock walls to the foundation. The roof is protected from wind uplift by steel strapping.
Interior Wall Construction
Drywall sheets are applied to studs, joists, or rafters with special drywall nails, drywall screws, or adhesive. Joints between panels are taped with a paper or fiberglass tape and coated, along with nail heads, by several layers of smooth, plaster-like wallboard compound (“mud”). Most outer corners are reinforced with metal or square-edged or rounded corner bead. The sheets, which are relatively inexpensive, are 4 feet wide, 1/4- to 5/8-inch thick, and 6 to 16 feet long. The standard size is 1/2 inch thick and 8 feet long.
Plaster is a mixture of Portland cement, sand, and water that is applied in a thick, mud-like consistency to a base of wood or metal lath or perforated plasterboard. It’s applied in layers. First, a scratch coat is troweled onto the lath so that it oozes through and grips the backing when it hardens. Then a finish or white coat is troweled on the scratch coat for the final, smooth surface.
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