Specification Choice - Level 5 Finish

A Level 5 finish is for use where gloss or semi-gloss paints or dark colours are specified or where critical lighting conditions occur on flat, satin or low sheen paints. Compared to the normal Level 4 finish, a Level 5 finish requires tighter tolerances of substrate straightness, will take extra time, use extra coating material at extra cost to achieve an enhanced uniformity of surface finish to minimise the risk of effects from glancing light on gloss or semi- gloss paint finishes or dark colours (refer CSIRO Division of Building Research Report L.8 Illumination and Decoration of Flat Surfaces and leaflet GLANCING LIGHT.) Even so expectations of a Level 5 finish providing a perfect flat surface are unrealistic.

FIXING OF PLASTERBOARD-CHOICES

GENERAL
The separate leaflet SPECIFICATION NOTES details that the minimum specification for use in contracts will be AS/NZS 2589.1.

The standard allows for a proprietary surface preparation or skim coating to be applied to remove differential surface textures and porosity.

The enhanced finish attainable at extra cost under Level 5 also depends upon proper substrate specification and installation.

SUBSTRATE
The substrate framing must be straight. The bearing surface of 90% of the framing must not exceed 3mm in 1800mm deviation (1 in 600) and the remaining 10% must not exceed 4mm in 1800mm deviation (1 in 450).

Builders must plan for and select the framing material and construction procedures well in advance of the job to achieve the above level of straightness. If this is not done the 'foundation' of a Level 5 finish is flawed and will not be achievable.

Proprietary metal furring systems, (using adjustable clips) attached to the lower truss chord can provide enhanced levels of straightness.

FIXING AND STOPPING
Standard fixing and stopping procedure for Level 4 finish (see leaflet SPECIFICATION NOTES) is applied.

This shall be followed by proprietary surface preparations or (in some areas) skim coating to remove differential surface textures and porosity between the paperfaced and jointed areas.

LEVEL OF FINISH

LEVEL 5
Where this level is required and the extra cost is justified the specification will be:

All framing, plasterboard lining, jointing and finishing shall be carried out to a Level 5 Finish, in accordance with AS/NZS 2589.1:1997 'Gypsum linings in residential and light commercial construction - Application and finishing Part 1 Gypsum plasterboard' - Appendix G.

PAINTING

Refer to AS/NZS 2311 -2000 Guide to Painting of Buildings.

PREPARATION
All plasterboard surfaces shall be thoroughly brushed down to remove dust and debris. Any minor surface variations shall be lightly sanded to a flush finish.

SEALER COAT
Prior to any painting, all surfaces shall be given one full coat of a proprietary plasterboard sealer, applied undiluted (unless otherwise specified) in accordance with the manufacturer's directions.

Subsequent coatings shall be applied according to paint manufacturer's recommendations after sealer coat is thoroughly dry.

The selected finishing paint shall be applied in two full coats. Application shall be made undiluted, (unless otherwise specified) using a roller or a brush for detailing.

FINISHING COATS
The finishing coat paints shall be 'named brand' paints supplied in manufacturer's containers.

Application may be by brush or roller. Under no circumstances shall paints be diluted more than the manufacturer's recommendation.

Each paint film shall be allowed to dry fully before subsequent coats are applied.