Before the end of World War II, the interior walls in homes and office buildings were almost exclusively made on site by laborers who applied wet plaster to an underlay called lath. Lath is a backing composed of thin strips of wood or metal, which is nailed to wall studs. Plaster was applied to the lath. The plastering process was extremely labor-intensive and time-consuming, primarily because wet plaster has a lengthy drying time. With the end of the War and veterans returning to civilian life, a housing shortage developed; construction companies wanted to increase output and shorten building times. To meet this demand, building trades turned to another method.
Beginning in the late 1940s, drywall (gypsum board) began to replace plaster and lath walls. Drywall allowed building contractors to build interior walls faster. Drywall or sheet rock, as it is sometimes called, is similar to plaster; but in the production process of drywall, gypsum plaster is pressed between sheets of paper and dried in an oven at the factory. Drywall is manufactured as wall-sized boards in varying thicknesses. Drywall is shipped hard and ready for installation. During the installation process, drywall is installed by nailing it to wooden framing and filling the seams with joint compound where the nailed sheets meet.
The differences between traditional plaster and drywall construction are illustrated below:
|Both plaster walls and those constructed of drywall start with the identical wooden framing.|
|A traditional plaster wall requires an underlay of wood or metal lath as a base for the plaster.|
Water is mixed into plaster and troweled onto the lath and allowed to dry. Once dry, this layer is sanded. Generally, up to three coats of joint compound are applied to the seams. Each coat must dry, and then be sanded before the next coat is applied. Once dry, this layer is sanded.
|A drywall finished wall entails nailing up hard pre-finished boards of gypsum.|
|Joint compound (also called joint cement) is mixed with water or scooped from a bucket of pre-mixed paste and applied to seams. After the first layer dries, it is sanded. Up to three coats of joint compound are applied to the seams. Each coat must dry and then be sanded before the next coat is applied.|
|The end product for both processes is the finished wall, which is ready for painting.|