8.5 Painting and decorating
SCOPE
DESIGN STANDARDS
| 8.5 - D1 | Design standards |
| 8.5 - D2 | Selection of paint and decorative systems |
| 8.5 - D3 | Compatibility |
| 8.5 - D4-D5 | Provision of information |
Design that follows the guidance below will be acceptable for painting and decorating.
SELECTION OF PAINT AND DECORATIVE SYSTEMS
When choosing paint or decorative systems account should be taken of the substrate.
Items to be taken into account include:
(a) timber
DECORATIVE SYSTEMS
Decorative systems should be compatible with the surface to be decorated which may be:
- bare timber
- stained timber
- primed timber
- preservative treated timber
- naturally durable species.
STAIN SYSTEMS
Stain systems for timber should be either:
- a 2 coat system, or
- in accordance with manufacturers' recommendations.
PAINT SYSTEMS
Paint systems for timber should be either:
- at least one priming coat, one undercoat and one finishing coat, or
- proprietary systems in accordance with manufacturers' recommendations.
PRESERVATIVE TREATMENT
Painting or staining of external timber is required to provide protection and stability even if the timber is preservative treated, unless the preservative treatment manufacturer confirms otherwise (see Clause D3).
MOISTURE CONTENT
Wood with moisture content above 18% is not suitable for priming/painting.
(b) masonry and rendering
Paint or decorative finishes should not be applied to external brickwork or render where the finish could trap moisture in the construction causing frost damage or sulfate attack or other detrimental effects.
(This applies particularly to bricks which have no upper limit on their soluble salt content. The brick manufacturer's written agreement to the application of any finish should be obtained in such cases.)
Paint systems for external brickwork or render, including proprietary surface preparations, should be appropriate for the substrate in accordance with the manufacturer's recommendations.
Where the decorative system is part of the weather resistance of the rendering, it should be assessed in accordance with Technical Requirement R3.
(c) metal
STRUCTURAL STEEL
Guidance on the protection of structural steel is given in BS 5493.
Internal and external steel which has not been galvanized should be protected with at least two coats of zinc phosphate primer and a suitable decorative finish, where required.
Internal and external steel which has been galvanized to a rate of at least 460g/m2 is acceptable without further protection. Steel galvanized to a rate of less than 460g/m2 should be protected with at least two coats of zinc phosphate primer and a suitable decorative finish, where required.
Where steelwork is to be protected by intumescent paint for fire resistance, the manufacturer's recommendations should be followed.
GUTTERS
Insides of metal gutters (other than aluminium) should be painted with a suitable protective paint.
NON-FERROUS PIPEWORK
Copper pipes, etc should be painted with the normal decorative finishes.
(d) plaster and plasterboard
Plaster and plasterboard surfaces should be prepared in accordance with manufacturers' directions for:
- plastic compound finishes
- wallpapers
- emulsion paints, etc.
(e) proprietary building boards
Paint systems should be either:
- at least one priming coat, one undercoat and one finishing coat, or
- proprietary systems in accordance with manufacturers' recommendations.
Other finishes should be applied in accordance with manufacturers' recommendations.
COMPATIBILITY
Items to be taken into account include:
(a) preservatives
Paint and stain systems specified should be compatible with any timber preservatives that have been used. Where appropriate, manufacturers' recommendations should be obtained and followed.
(b) stains and varnishes
Stains and varnishes should be suitable for the species of timber to which they are applied. Where appropriate, manufacturers' recommendations should be obtained and followed.
BS 6952 gives recommendations on the use of exterior wood coating systems.
(c) glazing compounds
Linseed-oil putty should not be specified for glazing rebates in windows and doors treated with stains.
Appropriate sealants should be used in accordance with manufacturers' recommendations.
PROVISION OF INFORMATION
Design information should include:
- specification of preparatory work
- schedule of finishes.
Ensure that design and specification information is issued to site supervisors and relevant specialist subcontractors and/or suppliers.
