BS 8481:2006 pdf download – Design, preparation and application of internal gypsum, cement, cement and lime plastering systems – Specification
3.2.4 one-coat plaster plaster applied in one-coat which fulfils all the functions of a plastering system
3.2.5 multi-coat plaster plaster system using a sequence of plaster coats to achieve the required thickness when all operations are completed after the plaster has set but not dry 3.2.6 undercoat lower plaster coat or plaster coats of a plastering system
3.2.7 final coat last plaster coat of a multicoat plastering system
3.2.8 dubbing out process of filling large localized irregularities in the background, such as hollows, prior to the application of an undercoat
3.3 Background definitions
3.3.1 background surface of a construction element to which a plastering system is to be applied
3.3.2 key roughness of a surface which enables plaster to make a bond
3.3.3 support product attached to the background to which a plaster is applied so that the plastering system is largely independent of the background (e.g. lathing)
3.3.4 reinforcement material incorporated within a plaster coat to improve resistance to cracking (e.g. mesh)
3.3.5 bonding agent proprietary material used to provide adhesion of the plastering system to the background where necessary
3.3.6 spatterdash and stipple pre-treatments to prepare a background for plastering
NOTE Stipple is only used in the form of site plaster.
3.4 Other definitions
3.4.1 efflorescence formation of crystals on a surface during drying caused by the presence of soluble salts
3.4.2 crazing network of short, irregular and very fine surface cracks up to approximately 0.2 mm in width NOTE Hairline cracks do not impair the function ofthe plaster and are therefore acceptable to a limited extent.
4 Materials and accessories
4.1 Materials for site-made plasters
4.1.1 Binders Gypsum binders and gypsum plasters If specified, only gypsum binders and gypsum plaster conforming to BS EN 13279-1 shall be used. Common cements including coloured cement Where used, common cements, including coloured and pigmented cements, shall conform to the requirements of BS EN 197-1.
NOTE Not all types and classes of cement are suitable for each and every application. Masonry cement Where used, masonry cement shall conform to the requirements of BS EN 413-1. Sulfate resistant cements If specified, sulfate resistant cements conforming to BS 4027 shall be used. Building lime Where used, building lime shall conform to the requirements of BS EN 459-1.
4.1.2 Aggregates Where used, aggregates with established suitability for use plasters shall be used. Aggregates shall conform to BS EN 13139 for dense aggregates or BS EN 13055-1 for light aggregates as appropriate.
4.1.3 Admixtures for cement and/or lime based plasters Where appropriate, admixtures with established suitability for plasters shall be used. Admixtures conforming to the requirements of BS EN 934-3 shall be used; however, admixtures falling outside the scope of BS EN 934-3 can be used given established usage and shall be applied in accordance with manufacturers’ instructions.BS 8481 pdf download.