The plaster forms a hard, durable surface when it dries and can be used to create decorative finishes, 3D elements, or textures. This final coat offers great soundproofing and insulation. This coat can go on smooth, or you can add various textures or finishes. White Coat : The top layer of plaster is applied after the brown coat has dried and cured.Brown Coat : The second coat is referred to the brown coat, which will start forming a smooth, level surface.Once the scratch coat dries, it will be smoothed and scored in preparation for the next coat. Scratch Coat : This is the base layer that is applied quickly and deeply to the lath and seeps into the gaps to form the “keys,” which will harden in place.The plaster is applied to the laths typically in three coats and are often referred to as the Scratch Coat, Brown Coat, and White Coat: Hiring a professional to repair your plaster walls is the best way to make sure that it’s getting repaired the proper way. It’s important to note that there are a few different kinds of plasters, such as horsehair plaster, gypsum plaster, and lime plaster. Then, plaster (a soft mixture of lime with cement or sand mixed with water) is applied to the laths to create a consistent, smooth surface. It’s commonly seen in older NYC apartments.īuilders use narrow strips of wood, called laths, that are fastened horizontally between studs or ceiling joists to create the wall or ceiling. You can scrape this back to leave you approximately 1/16” (2mm) ready for the top skim coat which can be blended with the surrounding area using a damp sponge as previously described.Lath and plaster is an older building method used to finish walls and ceilings. Repair or replace any damaged laths as before using Plasterboard or wire mesh, cutting them back to the nearest joist.īefore you apply the first coat of plaster, make the wooden areas damp using a wet sponge then trowel on the first base coat, don’t build this up too thickly, scratch key the surface then allow it to set, and then apply a second thinner base coat. I find these Bole safety glasses very comfortable to wearĬut the plaster back far enough to remove any loose or blown areas allowing you to work with a sound and solid surface. You can use a multi-function scraper to help lift the plaster away and I often use an 18V Multi-tool with an old, wide wood cutting blade to cut the plaster, taking care not to cut too deep and damage the wooden laths underneath.Īlways wear eye and face protection when working overhead to help prevent any plaster from causing an accident. Use a sharp utility knife to trim around the damage and then carefully pull the plaster away from the laths behind. Trowel on the first coat and press it into the surface to ensure a good bond onto the laths, then scratch key the surface and let it set.Īpply a second topcoat using a trowel and use a darby to level it with the surrounding surface, to blend the edges use a damp sponge to feather the new plaster over the old existing surface.ĭamaged ceilings are often seen in older houses, usually due to water damage from a burst pipe or a leaking roof, the brown patchy stains are a tell-tale sign of water damage,Īs with repairing lath and plaster wall, the old, damaged plaster surface needs to be removed from the ceiling. If the level of the original plaster is very deep, consider using a two-coat method for applying the plaster. If you have used plasterboard as a new sub-base, make sure this does not get wet, otherwise, the paper surface will deteriorate and the surface will fail. To get a good bond, I prefer making the wooden laths slightly wet with a damp sponge, this prevents them from sucking too much moisture out of the plaster. You can learn more about applying and skimming plaster in our How to Plaster guide Allow the mixture to stiffen then trowel the surface as you would for any other plastering project Smooth and level the surface using a flat, straight edge or plastering darby, and fill in any low spots or hollows. Then build up the layer until it is level with the original plaster. To repair the surface you can use a one-coat plaster and skim the plaster on by hand using a trowel, at first pressing the mixture so that it bonds firmly between the laths or the plasterboard Build up layers until flush with the surrounding plaster, allow it to stiffen then smooth with a trowel and blend the edges with a damp sponge. Trowel the first layer of plaster over the whole area pressing the mix firmly into the laths. Once the sub base has been repaired and is sound, it can be replastered to give you a clean, smooth surface to decorate.ĭampen the laths with a wet sponge, avoid making any plasterboard wet as this will destroy the paper covering.
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