Gypsum plaster
When a wall is constructed with brick or block, they are finished with a coat of plaster which is called internal plastering.
Backing coat which is the underlying coat that sits on the substrate can be one of several plasters designed for a particular use.On this is placed a skimming coat again which can be of several types. Some interesting plasters are x-ray plasters which are very heavy and lightweight plasters such as board or multi finish.
Dry Lining
Dry lining is technically the covering of a background surface with a plaster substitute; Masonry, block work and generally brickwork are unacceptable as a finish not only for aesthetic reasons but also because they generally are not as true as a plastered finish.
Dry lining is the fitting of plasterboard or a board material akin to plasterboard to any surface in lieu of a hard plaster.
Dry lining doesn’t require anywhere near the amount of water that traditional plastering needs and to some degree less technical expertise to fit than plaster. Plasterboards are produced by leading manufacturers in huge factories and in great volume. Plasterboard is available in various lengths, widths and thicknesses.
When dry lining and fixing plasterboard to timber or metal this is referred to as ‘tacking’ if using nails, or ‘screwing’ when screw fixings are used.
Screws will always support the plasterboard better than clout nails and we recommend whenever possible to follow this recommendation.
Dry lining to timber or metal is reasonably straightforward providing you follow a few basic principles.
Always choose the most suitable plasterboard or board for the job in hand. If you’re dry lining a wet area, maybe a bathroom consider the extra value moisture resistant plasterboard will give you. Moisture resistant plasterboard is normally green.Moisture resistant plasterboard however will not stand being submersed in water for long periods and the core is like any other board making unbound or cut edges susceptible to water penetration.
Lafarge produce an aqua board and Knauf an ‘Aquapanel’ plasterboard, both of which are extremely water resistant. The Lafarge aqua board can even be used in external lining applications.
The plasterboards are then skimmed with a board finish gypsum plaster and trowelled flat to provide a smooth finish for decoration