Internal finishes

Plastering
The selection and application of plasters should be in accordance with BS 5492: Code of practice internal plastering and BS 8000: Part 10: Code of practice for plastering and rendering.

In general there are five different groups of plastering mixes:

a) Mixes based on cement, or cement and lime
b) Lightweight cement plasters
c) Premixed gypsum plasters
d) Premixed lightweight gypsum plasters
e) Mixes based on gypsum plasters gauged with lime

The mixes and application of lightweight and gypsum based plasters should be in accordance with the manufacturer’s instructions.

Cement, or cement and lime based plasters are normally limited to the undercoat for general two coat plaster work as it is often difficult to obtain a very smooth finish with mixes containing sand. This being the case, the final coat is normally a gypsum or lightweight plaster mix compatible with a cement based undercoat.

For general purpose work, the mix for the undercoat is the same as that given for designation (iii) in table 13 of BS 5628: Part 3 for rendering mixes. The overall thickness of two-coats in cement-based or gypsum plaster on masonry should be nominally 13mm.