Plastering exterior walls is called rendering and involves applying a fairly thin layer of a cement, sand and lime mix. Although these types of exterior finishes are usually applied when houses are built, there may be times when repairs have to be made or the old plaster is removed and re-rendered. Render is applied in two coats: an undercoat called the float coat and a thinner, finishing coat.
If rendering an exterior wall, remember to carry out the work in mild weather as freezing temperatures will freeze the water in the render, causing it to crack. The typical render mix is:
When mixed with water you should try to achieve a workable consistency: not too wet and not too dry. Render dries out quickly so don't mix too much at one time, as it will be too stiff to trowel across the surface of the wall after about 20mins.
This is a popular alternative to the usual practice of applying an undercoat and finishing coat. One-coat plaster can be used on most indoor surfaces: bricks, blocks and plasterboard. Mixed with cold, clean water it will dry either white or pink depending on the brand. It can be applied in a layer of up to 50mm (2in) thick if filling in a cavity, but generally it is applied 10mm (3/8 in) thick. At this thickness 8kg will cover 0.7m2. One-coat plaster remains workable for between 30mins and 60mins depending on the room temperature.
A fast-setting compound used to repair damage to plaster walls and ceilings.
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