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Lime render is a plaster made with lime that people can apply to the walls of a building to protect it from the elements. The process of applying this product is known as rendering. Old masonry buildings are a common target for rendering, and it may be used with other types of building materials as well. In some regions, contractors familiar with the process can apply lime render for customers, and in others, people may need to do it themselves.
Once lime render cures, it confers a number of advantages to the underlying structure. Lime readily absorbs water, and in the rain, it will be able to absorb the moisture, holding it away from the wall. As the weather dries up, the covering's breatheability allows the water to evaporate so it cannot penetrate the inner walls. It has room for expansion and contraction, preventing unsightly cracks, and will not trap water inside the walls because any liquid will evaporate through the porous surface.
Cement and sand mixtures have a long history as well coverings, but lime render, an even older product, is actually better in terms of the protection it offers. Cement traps water and will start to crack and chip in cold, wet weather, exposing the underling stone to the forces of erosion. Lime render protects the underlying surface, especially if people regularly clean the walls and reapply at the first signs the rendering is starting to fail. It also takes paint readily, allowing people to paint structures in any color they want.
This external coating for buildings is available at hardware and home supply stores in the form of a dry powder that needs to be mixed with water before application. Several different styles are made, and it is also possible to purchase colored lime render, allowing people to skip the need for painting. It is important to clean the surface well before applying, and to wet it down to increase the bond. In some cases, builders may recommend treating the wall with a product to enhance binding if the material is slippery and will not cling well to the lime coating.
Regions with a history of masonry construction often have homes treated with lime render along with contractors familiar with the process. Those preparing for restoration and maintenance of an old masonry structure can discuss whether they need lime render with a contractor. Buildings made from weak, porous, and crumbling materials usually need a layer of protection to keep them in good condition.