The end product for both processes is the finished wall, which is ready for painting. If a plasterer skimped on materials, the wall may not have. Each coat must dry and then be sanded before the next coat is applied. Using rock lath allowed the plasterer to apply one base coat and the finish coata two-coat job. The work took a long time and was very labor intensive. The walls of any pre-war house are most likely wood lath like in this picture covered with 3 coats of plaster. Up to three coats of joint compound are applied to the seams. 5 Worst Mistakes of Historic Homeowners (Part 4 Plaster) January 2, 2012. After the first layer dries, it is sanded. Joint compound (also called joint cement) is mixed with water or scooped from a bucket of pre-mixed paste and applied to seams. Each coat must dry, and then be sanded before the next coat is applied. Once dry, this layer is sanded.Ī drywall finished wall entails nailing up hard pre-finished boards of gypsum. Generally, up to three coats of joint compound are applied to the seams. Walls and ceilings that use metal lath for the plaster base should be divided into rectangular panels with control joint at least every 18 feet or at the juncture of a dissimilar wall, or in either direction in a length to width ratio of 2 to 1, or in ceilings exceeding 100 sq. Water is mixed into plaster and troweled onto the lath and allowed to dry. using info found under Lath Fasteners section. The differences between traditional plaster and drywall construction are illustrated below:īoth plaster walls and those constructed of drywall start with the identical wooden framing.Ī traditional plaster wall requires an underlay of wood or metal lath as a base for the plaster. 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. Drywall is shipped hard and ready for installation. Drywall is manufactured as wall-sized boards in varying thicknesses. 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. To meet this demand, building trades turned to another method.īeginning in the late 1940s, drywall (gypsum board) began to replace plaster and lath walls. 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. The plastering process was extremely labor-intensive and time-consuming, primarily because wet plaster has a lengthy drying time. Lath is a backing composed of thin strips of wood or metal, which is nailed to wall studs. There are several ways in which to repair lath and plaster - using modern or traditional techniques, or by learning how to patch plaster.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. If, on the other hand, large chunks of your wall or ceiling are coming away, more significant repair work will be necessary. Simply check them regularly and keep an eye on any new cracks that appear - often simply skimming over them with a suitable, lime-based, plaster mix is sufficient. a 3/8' thick rough coat of plaster or maybe a rough coat and scratch coat that are very similar in composition, where the rough coat is from the 3/8' mark to the 5/8' mark on your tape. a 3/8' thick layer of rock lath or gypsum board lath. Of course, if your walls are still in good condition, there is no need to touch them. So from the top down and starting at zero on your tape, we have. If you live in a house with lath and plaster walls (likely if your house was built before 1940) then you might be wondering how to repair damaged lath and plaster. How do you Repair Lath and Plaster Walls? These mixtures usually used a 1:1:6 combination of gypsum or cement, lime putty and sharp sand for the initial two coats, then equal parts of lime putty and gypsum for the final layer. Later on, it became common to add in gypsum or sometimes cement - this was to speed up the setting process between each layer. The third layer was commonly made up of lime putty and a fine sand in a 3:1 mixture - or sometimes just lime putty. The first two layers of plaster that were applied to the lath were usually made up of lime putty and sharp sand in a 1:3 ratio - often with animal hair added in to help bind them. (Image credit: Getty) What Type of Plaster Was Used For Lath and Plaster? Lath and plaster walls were commonplace in house right up until the advent of plasterboard in the 1930s.
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