Plasterboards

Building Advice and Guidance for Plasterboards

Imagine building a stud partition wall and then nailing thin strips of wood known as laths to the wall, covering it completely. Once you have finished this arduous task you will then need to plaster the wall to create a smooth finish. This labour intensive method of providing a finish to walls and ceilings was eventually superseded in the early 1900’s by plasterboard sheets.

The sheets are made by wrapping a gypsum plaster mix in paper which is then allowed to set in large drying chambers. The design has evolved to cater for a wide variety of situations, both domestic and commercial. For instance, it is possible to obtain specially formulated boards suitable for fixing into showers and very wet areas. These boards are cement based and thus more rigid than a standard sheet. For areas that are to be tiled boards can be fitted that have fiberglass matting which will prevent the tiles from moving or cracking. Plasterboard with extra fire resistance can be fitted to walls that require a higher specification, and sound shield boards will provide an increased acoustic performance.

Plasterboards with insulation directly bonded are available for increasing thermal and acoustic insulation.

Plaster board being installed

Plaster board being installed

The method of fixing plasterboard will depend on the surface it is to be applied. For solid block or brick walls normal practice is to ‘glue’ the boards by applying a drywall adhesive to the walls with a trowel. When mixed with water the adhesive resembles thick plaster and would be applied to the wall in several large spots and the board is then fixed to the wall. The boards are tapered with a straight edge so that they are flat and level. It is important to make sure that the adhesive will stick to the wall and so it is good practice to coat the wall first in a diluted mix of bonding PVA and allow it to dry.

When the boards are fitted to timber studwork then drywall screws are used. It’s useful to mark where the studs are on the board before fitting to be sure that the screws don’t miss their mark. The edges of the boards need to finish on a timber so that there is no movement and then the edges are taped.

Plaster board dot and dab fixing on waterproof membrane

Plaster board dot and dab fixing on waterproof membrane

There are two ways of finishing a wall once the boards have been fitted. If the wall is to be ‘dry lined’ then boards with a tapered edge would be fitted. This would allow for a small depression along the joints. Once the joints have been taped filler is trowelled over the joints and allowed to dry. This is then rubbed down and filled again to provide a finish. The whole wall can then be decorated. When coating plasterboard with emulsion it is a good idea to provide a first coat that is watered down by at least 50% before painting subsequent coats.

Tile backer board

Tile backer board

Below is a list of Plasterboards and their uses. Std Dimensions 2.4m or 3.0m long x 1.2m wide

Wall Board Std.                    

Ivory faced. Suitable for most applications. Finish with multi finish or thistle plaster.

Wall Board Tapered edge.       

As above with Tapered edge on the long sides for finishing with a joint filler.                     

Sound Block                               

 Has a high density core for situations where greater levels of sound insulation are required.

Fire Line                                      

Has a core of plaster & Glass fibre used to provide a greater level of fire protection.

Core Board

19mm thick provides fire & moisture protection to shafts during construction. 600mm x 3.0m

Impact resistant Board

High density core with fibre glass and other additives to provide better impact resistance.

Moisture resistant Board

Plaster board with a water repellent additive in the core & paper lining

Thermal Board                         

STD Plasterboard with insulation in varying thicknesses directly bonded to the board.

Tile Backer Board

For use in waterborne areas such as shower rooms. Has a high resistance to water.

Thermal backed plaster board

Thermal backed plaster board

Image credit: Red Moon Sanctuary