Number of Plaster Coats for Different Backgrounds
The ideal number of coats, where practicable, is two, namely, the undercoat followed by a finishing coat. It is recognized, however, that much successful work has been carried out in the past with only a finishing coat plaster on reasonably plane backgrounds of brick, concrete and similar materials. However, for very rough surfaces, such as rough stone masonry, three coat plastering may be necessary. Metal lathing normally requires a three coat plaster finish for successful results. Renovation work on wood laths should also be carried out in three coats.
The range of coats normally employed for different backgrounds is as given in table below.
|
Background |
Number of Coats |
|
Brickwork or hollow clay tiles |
2 or 1 |
|
Concrete, cast in situ |
2 or 1 |
|
Building blocks |
2 or 1 |
|
Wood or metal lath |
3 or 2 |
|
Fire building board (insulating board) |
2 or 1 |
|
Wood wool slabs |
2 or 1 |
|
Cork slabs |
2 or 1 |
|
Uneven and rough stone masonry |
3 or 2 |