Lighting& Decoration THE FACTS February 2005

INTRODUCTION

Contents:

2

Introduction

Page 3 - 4

General

Page 5 - 6

Influences

Page 7

Glancing Light

Page 8 - 12

Lighting

Page 13 - 15

Favourable & Unfavourable

Page 16 - 17

Gloss/High Paints

Page 18

Preparation & Application

Page 19

Paint Discolouration over Jointed Surfaces

Page 20 - 22

Levels of Finish

Page 23 - 24

TecASSIST

Page 25

Notes

Page 26 - 27

Boral Plasterboard - Lighting & Decoration The Facts

This publication has been compiled as a guide for Building Designers, Contractors and Property Owners. Its contents include the following:

INTRODUCTION

Introduction 1. An outline of the various types of light sources – both natural and artificial – used to illuminate exteriors and interiors of residential and commercial buildings.

2. Explanations of the problems arising when illuminating flat surfaces using many of the light sources available.

3. Suggestions of what to do – and what to avoid – in order to lessen the problems when they arise. 4. The effect of illumination on decorative finishes – such as gloss paint. It is our intention to illustrate some of the problems that arise while trying to provide the expected flat plasterboard finishes. These effects can be experienced by even the most highly-skilled tradesperson rigidly following installation recommendations. We will provide a number of suggestions that contribute to achieving a satisfactory result: • A planned approach towards lighting design. • Accurate installation of wall framing and roof trusses. • Lining installation and finish to Australian/New Zealand Standard 2589 and the appropriate finish. • Good painting practice. It has been our experience that when the above are given due consideration, considerably improved results can be achieved. Published by Boral Plasterboard as a service to the building and construction industry, this booklet is a general guide to understanding lighting problems and providing solutions. It is recognised by the following Australian organisations:

Boral Plasterboard - Lighting & Decoration The Facts

3

INTRODUCTION 4

Lighting problems can be caused by: Large Uncurtained Windows (see page 4)

A batten holder without light shade (see page 12)

Outdoor reflective surfaces (see page 7)

Ceiling fluorescent lights

Incorrectly positioned spotlights (see page 10)

Indiscriminate use of gloss paints (see page 14)

(see page 12)

Boral Plasterboard - Lighting & Decoration The Facts

There is little doubt most consumers’ expectations of plasterboard finishes is an absolutely flat blemish-free surface. There is also no doubt that in most cases, this view is shared by your builder, painter and plasterboard fixer as exactly what they set out to achieve.

GENERAL

General In reality, an absolutely flat blemish-free finish is difficult to achieve. In fact, all that can ever be expected is the illusion or appearance of flatness. It really makes little difference whether we are dealing with someone’s million dollar mansion or a modest dwelling, the finished appearance will in most cases be determined by: (a) The amount of glancing light projected onto a particular surface – either natural or artificial. (b) The paint system, paint type and/or application. (c) Good installation practice by the framing carpenter and plasterboard fixer.

Large uncurtained windows allow exterior glancing light to emphasise imperfections on adjacent walls and ceilings from external reflections, especially water.

Boral Plasterboard - Lighting & Decoration The Facts

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GENERAL

How natural light affects your house EARLY MORNING SUNLIGHT Glancing Light – Warmer (more orange) than overhead sunlight. Casts deep elongated shadows and emphasises both decorative detail and imperfections in surface texture on walls and ceilings.

LATE AFTERNOON SUNLIGHT Similar to early morning conditions but, obviously, the sunlight and shadow directions are reversed. Effects may be more intense than early morning and of longer duration on walls and ceilings.

DIRECT SUNLIGHT Strong overhead light. Intense shadows directly beneath objects. Washes out decorative detail and minimises imperfections in surface texture. Emphasised by bulkheads, skylights and atriums.

REFLECTED SUNLIGHT Waterfront properties and/or those with outdoor swimming pools usually reflect back harsh sunlight onto the surface of the building. The effect can be worse than straightforward glancing light in that it strikes (and affects) the surface from many angles.

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Boral Plasterboard - Lighting & Decoration The Facts

There are many factors in modern building design that influence the overall appearance of a wall or ceiling. Many of today’s home interiors are created to provide the effect of spaciousness, with lower unbroken ceiling areas across adjoining rooms, large open living areas, and importantly, larger windows with greater use of natural light from skylights and mirrored walls etc.

INFLUENCES

Influences While benefiting the desires of the increasingly ‘design educated’ consumer, these modern features often create conditions in which it is difficult to achieve the desired level of finish. While confident of their quality expectations, consumers are not often aware of the difficulties involved in achieving these expectations, particularly when some design conditions highlight rather than camouflage surface defects. It is therefore very important that the consumer’s expected standard of finish equals the ‘level of finish’ the tradesperson is capable of achieving given the particular design specifications of the project. Levels of Finish *See additional references: - AS/NZS Standard - Levels of Finish in Plasterboard Jointing & Finishing - CSIRO Notes

A modern-day wall of glass and yesterday’s smaller windows.

Boral Plasterboard - Lighting & Decoration The Facts

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GLANCING LIGHT

Glancing Light When architects, specifiers, builders or home owners are considering the type of finish they require from plasterboard walls and/or ceilings it is important to understand how the overall appearance is likely to be affected by glancing light. Glancing light is the light that shines directly across the surface of a wall or ceiling. No building material, including a gypsum plasterboard interior lining system, can provide a perfectly flat or defect-free ceiling or wall finish. We know the common requirement is a completely flat surface; however, despite our best intentions, this is not always possible to achieve and imperfections can and will be highlighted by light falling almost parallel to the surface. This lighting effect is termed glancing light. Glancing light tends to magnify imperfections and/or blemishes and can destroy any flat finish that has been created. Plasterboard wall and ceiling systems comprise of a number of different surface finishes, porosity and texture variances, these exist at pre-paint stage. When considering the type of finish required from plasterboard it is important to understand how the overall appearance is likely to be affected by glancing light. Finished plaster joints are subjected to many different lighting conditions. Lighting intensity changes constantly throughout the day or night, depending on the position or direction of the lighting, the sun’s reflections, or light bouncing off adjacent buildings, water surfaces etc. The worst instances of glancing light can occur with single unshaded light source fixed directly to the ceilings or walls, but can also occur in rooms with windows up to ceiling height or windows adjacent to walls.

Glancing light reflected upwards from pool water onto interior walls & ceilings.

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Boral Plasterboard - Lighting & Decoration The Facts

Diffused frontal lighting

2a

Horizontal plasterboard joint 1a

3a

Lit by frontal light which reduces or eliminates shadows to give a virtually blemish-free illusion of flatness to the surface.

GLANCING LIGHT

Vertical plasterboard joint

Glancing light Vertical plasterboard joint

2b

Horizontal plasterboard joint

1b

Boral Plasterboard - Lighting & Decoration The Facts

3b

Lit by glancing light which deepens and emphasises shadows caused by surface imperfections.

9

GLANCING LIGHT

Plasterboard ceiling under glancing light conditions.

10

Boral Plasterboard - Lighting & Decoration The Facts

GLANCING LIGHT The same ceiling under different lighting conditions when viewed from another angle.

Boral Plasterboard - Lighting & Decoration The Facts

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GLANCING LIGHT

Because the angle of the light illuminates even the most minute undulation and creates a shadow on the other side, imperfections are highlighted that under a more diffuse light would normally not be visible. In order to eliminate this glancing light effect on interior surfaces a number of factors can be considered:

1.

Either utilise suspended or recessed ceiling lights or alternatively, select shades that direct light downwards or directly at the picture to be highlighted (feature light).

2.

Utilise a number of lower-watt lightbulbs, rather than one or two bright ones to illuminate the room and reduce the shadowing effect.

3.

Diffuse the light entering the room through windows by using mesh curtains or other diffusers to disperse and soften light flow.

Lighting is very much a matter of cause and effect. Simply by understanding the role that light fittings play, and the consequence of their positioning, it is possible to minimise adverse effects on quite normal standards of workmanship. The most severe case of glancing light will occur when a surface-mounted fluorescent batten fitting is placed in the centre of a ceiling parallel with the plastered joints. They produce a high output white light at a shallow angle and magnify any surface irregularities.

Incorrectly positioning a spotlight to highlight an object can also shine glancing light on to walls and ceilings and emphasise surface defects.

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Feature lights such as that shown above will light only featured object.

Boral Plasterboard - Lighting & Decoration The Facts

Lighting Lighting is one of the most important elements in the design of a new home and can add that special finishing touch. It is quite possible to make almost any room look better simply by using a planned/informed approach to lighting. Be aware of the effects that glancing light can create when making decisions on the type of lighting and its positioning.

Although the selection of light fittings is usually governed by taste and budget, it is wise to choose your lighting requirements carefully before you begin building. As open living designs feature larger rooms, living and family areas etc, these areas are the most severely affected by glancing light. Consideration should be given to general diffused light from downlights or spotlights in combination with local accent lighting such as standard lamps, table lamps etc.

LIGHTING

Today’s modern lighting techniques can use balanced illumination with shadow by providing a little thought and planning, you will get greater satisfaction from your new home.

BE AWARE • Fluorescent lights installed in kitchen areas that form part of a large open living area will, in most cases, create unfavourable effects on the other ceilings by highlighting irregularities and shadows in the finished surface. • In two storey dwellings, some downlights may not fit between the floor cavity, so plan ahead.

Boral Plasterboard - Lighting & Decoration The Facts

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LIGHTING

Recessed ceiling lights, spaced correctly, give adequate illumination and do not highlight texture irregularities on walls and ceilings.

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Boral Plasterboard - Lighting & Decoration The Facts

LIGHTING

Boral Plasterboard - Lighting & Decoration The Facts

15

LIGHTING

Favourable & Unfavourable Lighting

16

FAVOURABLE

UNFAVOURABLE

An opaque shade directs the light downwards to illuminate the room not the ceiling.

A batten holder without lampshade casts harsh ceiling light to highlight imperfections.

A recessed fluorescent light avoids ceiling shadows and does not highlight texture irregularities.

Unguarded fluorescent lights close to the ceiling both illuminate surface imperfections near to the tube and cast ugly shadows on the ceiling.

Boral Plasterboard - Lighting & Decoration The Facts

FAVOURABLE

UNFAVOURABLE

Recessed down/spotlights avoid glancing light by providing good, even downward illumination.

Plasterboard joint

Under some circumstances, it may be expedient to install fluorescent lights directly over butt joints in order to conceal the joints. Plasterboard joint

Plasterboard joint

An area of ceiling in daylight. No imperfections are visible when ceiling light is off.

Boral Plasterboard - Lighting & Decoration The Facts

Never run fluorescent lights in the same direction as plasterboard joints. Position lights so that the light caps face joints - and so avoid illuminating any surface defects around joints.

LIGHTING

Plasterboard joint

A ceiling mounted circular fluorescent light provides very strong glancing light close to the surface and makes any imperfections glaringly apparent.

The same area at night when lit by ceiling mounted round fluorescent light.

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Gloss/Sheen Paints Full gloss paint finish is not recommended on plasterboard walls or ceilings. When semi-gloss paint is to be used in large open rooms or vast areas of uncurtained windows, then the highest level of finish is essential. If cost factors preclude this investment, then very careful consideration must be given to: • The placement of windows. • The standard of paint finish. • Building aspect – Northerly? Westerly?

• The type of lighting. • The positioning of joints both butt and recess.

G L O S S / S H E E N PA I N T S

Please Note: Horizontal joints are recommended for walls with areas of severe glancing light. Gloss paint, and even semi-gloss paint, on flat surfaces reflect light in a pattern distorted by the imperfections of the surface. This effect is enhanced as the observer moves around the room and the image changes in relation to the changing position when viewing the same surface. Flat paints, on the other hand, tend to reflect light back in a diffused form which does not draw the observer’s attention to the lining surface. It should be pointed out that plasterboard is a machine-made product with a textured paper surface. In most cases the jointing is a hand-applied operation and, when sanded, the two different surfaces are evident and, for this reason, gloss paints should be avoided where possible. It should be emphasised that, in some cases, gloss or impervious sheen paint finishes may be desirable for purely functional reasons e.g. kitchens, bathrooms etc. In which case, some loss of appearance will have to be accepted. Our observations are that, even when the work has been carried out by the most highly skilled tradesman, the end result can be most disappointing when gloss paints are used for decorating purposes. Full gloss paint finishes on plasterboard walls or ceilings is not generally recommended as providing a totally satisfactory finish is a difficult process.

Left surface area was finished with matt paint; right surface area with gloss paint.

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Boral Plasterboard - Lighting & Decoration The Facts

Preparation & Application The following comments should be taken as a guide in an effort to improve preparation and painting of plasterboard surfaces. • All surfaces should be clean and dust free prior to painting. • First coat should be a recommended sealer roller applied, not sprayed. If the spray method is used to paint the ceiling or wall, it is recommended that the surface be backrolled as recommended by the master painters of Australia and allowed to thoroughly dry prior to the application of the second coat. • Lightly sand between coats. • Any major defects made obvious by the first coat of paint would normally be referred to the plasterboard contractor for further attention before proceeding with second and final coats.

It is understood that the normal sequence of events when painting plasterboard would be for the painter to attend to minor blemishes and sanding on the surface between coats. APPLICATION – SPRAY PAINTING Contrary to popular belief, the spray method of painting is not the recommended application for the painting of plasterboard. • The spray method of painting emphasis face paper napping and highlights joint lines. • Spray application does not equalise the surface of what is basically two completely different materials (paper faced plasterboard and porous joint compound). • Spray painting application should be immediately back rolled to provide best results. Boral Plasterboard recommendation for the proper coverage of plasterboard is to first use a suitable sealer over the entire surface in order to equalise the porosity and varying textures. Choice of colours is also important as some darker colours tend to highlight imperfections. White gives better reflections and is recommended for ceilings. POINTS TO REMEMBER 1. In buildings, there is no such thing as a

4.

Glancing light is caused by natural external conditions and certain types of internal lighting.

5.

Detrimental circumstances include: • Large uncurtained windows. • Unshaded lightbulbs. • Ceiling-mounted fluorescent lights. • Badly-positioned spotlights.

perfectly flat surface.

2. 3.

Even after the most careful professional finish, every surface contains flaws and imperfections. The imperfections are normally invisible under most conditions. However, glancing light and gloss paint will emphasise any blemishes.

Boral Plasterboard - Lighting & Decoration The Facts

• Indiscrimate use of gloss paint. • Outdoor reflective surfaces – e.g. pools, canals, adjoining steel roofing and painted walls. • Running plasterboard joints parallel to fluorescent lights.

P R E PA R AT I O N & A P P L I CAT I O N

TRADE SEQUENCE

For more information, please call Boral TecASSIST on 1800 811 222.

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Paint Discolouration over Jointed Surfaces. Moisture associated problems in ceilings can result from a wide range of sources: • Water leaks migrating to joint location and transporting dust. • Animal waste from vermin entering the ceiling cavity. • The addition of Joint Compound contaminates (eg. accelerators/retarders). • Poor quality paint or decoration procedures. • Inadequate ventilation.

D I S C O L O U R AT I O N

• Inadequate insulation, especially in regions with high humidity and temperatures variations. Example 1: The joints, fastener points, and the imprint of the ceiling battens can be seen from below. The problem seems to be most obvious in the colder climatic conditions/regions ie. ACT, Tasmania or in Alpine Region and especially when preparing meals or while the heating system is operating. The Plasterboard ceiling installation appears to conform to the Australian Standard/New Zealand Standard 2589.1:1997.

Example 1

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Boral Plasterboard - Lighting & Decoration The Facts

OBSERVATIONS • The temperature in the ceiling cavity is much lower than inside the home. • No ceiling insulation. • Little or no cross flow ventilation in the ceiling cavity. • No ceiling fan or hood above the stove or oven to provide ventilation passage in order to exhaust smoke and or steam vapours from the source. • There has been no sealer coat paint preparation. OUTCOMES • Steam generated by the stove rises and makes contact with the cold surface of the ceiling forming moisture drops on the unsealed cold ceiling surface. • Moisture penetrates the most porous surface especially the unsealed joints and fastener points and retains a higher moisture level than other areas. • The coldest locations are steel fasteners or where metal battens are hard against the rear of the plasterboard ceiling. Naturally colder than the Plasterboard they support, these areas retain moisture in the porous areas immediately surrounding them. This causes the plasterboard to gradually look damp and lose its integrity.

• Install appropriate R levels of batt insulation in the ceiling. • Introduce fixed cross flow ventilation in the ceiling cavity. • Provide exhaust ventilation in the cooking and food preparation areas. • Allow the ceiling board to dry out thoroughly. • Inspect the ceiling joint surfaces for fungi and treat if present. • Repair any fastener points needing attention. • Use a quality paint to repaint with an approved roller applied sealer coat following the paint manufacturers recommendations.

D I S C O L O U R AT I O N

RECOMMENDATIONS

Reference documents: 1. CSIRO Notes on the science of Building No 61: CONDENSATION in Houses 1991. 2. Some Condensation Problems No 78 1994.

Boral Plasterboard - Lighting & Decoration The Facts

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Paint Discolouration over Jointed Surfaces in Subtropical and Tropical Regions. In recent years a growing number of concerns have been raised regarding plasterboard jointing surfaces being visible after decoration. This has prompted plasterboard manufacturers in Australia to conduct detailed studied into these issue. Mould and or mildew growth, contaminated paint, sheen staining, gloss bandings, paint yellowing due to age, mud cracking, nap raising, staining and smoke affected joints are among contributing factors of paint discolouration and visible joints. Any of the above can occur randomly and appear over even the most professional tradesman like plaster finishes. Discolouration can present itself intermittently throughout the residence, particularly in the kitchen, living and bathroom areas and mysteriously is seldom evident in well ventilated areas like the garage. When problems occur at the painting stage it has become common place for industry to suggest jointing compound retarders, additives, and/or contamination however with today’s range of modern formulated joint compounds there is no longer a need for additives that either accelerate or delay the setting times. Recent tests on Boral Plasterboard jointing compounds demonstrated clearly they contain nothing that is incompatible with paint formulations.

D I S C O L O U R AT I O N

Manufacturers specifications for the decoration of plasterboard are identical, all recommending a three coat system. A quality paint finish is more difficult achieve without top grade paint, industry cannot achieve an acceptable level of finish using a low cost system. We work in a price driven industry that fosters contractor competition. Paint is similar to most other products in the building industry in as far as you get only what you pay for, although to the untrained eye, the finish probably looks the same, unfortunately the real cost only becomes apparent at maintenance time.

Example 2

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Boral Plasterboard - Lighting & Decoration The Facts

Levels of Finish Determining the Level of Finish Australian/New Zealand Standard AS/NZS 2589.1:1997Gypsum Linings in Residential and Light Commercial Construction Application and Finishing. Part 1: Gypsum Plasterboard. This standard applies a system called ‘levels of finish’ to determine the quality of finish desired. AS/NZS 2589.1:1997 defines 6 (0-5) levels of finish. Each level requires a minimum set of specifications covering the installation process from framing to coating. The level of finish required is determined at the design stage. This is essential since each level of finish requires specific tolerances for frame alignment and plasterboard fixing and finishing. The desired level of finish is achievable only when these requirements are met throughout the stages of construction. The level of finish also affects the methods of jointing (particularly butt jointing and back-blocking), the number of coats of joint compound applied, and the fitting and finishing of stopping and corner/angle accessories.

Defined Levels of Finish LEVEL 0 May be useful in temporary construction. No stopping, taping, finishing or accessories required. Work involves only gluing and screwing/nailing plasterboard sheets in place. LEVEL 1 Used in concealed applications as in plenum areas above ceilings and in building service corridors. All joints and interior angles have tape embedded in joint compound. Surface is to be free of excess joint compound. Tool marks and ridges generally acceptable. Accessories in pedestrian spaces are optional.

Boral Plasterboard - Lighting & Decoration The Facts

LEVELS OF FINISH

A level 4 Finish is the quality of finish generally applied in domestic construction, unless a higher or lower level of finish is specified. When in doubt, consult your nearest Boral Plasterboard sales office.

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LEVEL 2 Suitable for storage areas where surface appearance is not of primary concern. All joints and interior angles shall have tape embedded in joint compound. Apply one separate coat of joint compound over all joints and fastener heads. Surface to be free of excess joint compound. Some minor tool marks and visible edges acceptable. LEVEL 3 Suitable for surfaces intended to have heavy or medium texture finishes through sprayed or hand-held application. Also where heavy wall covering is the desired final decoration. All joints and interior angles shall have tape embedded in joint compound. Apply one separate coat of joint compound over all joints and fastener heads. Finish all joint compounds smooth. This is easily done by scraping off nibs and ridges with the edge of a trowel. LEVEL 4 The accepted level of finish for domestic construction. Use where critical lighting shines on light textures, light wall coverings and smooth textured finishes. Also where smooth textured finishes and satin/flat/low sheen paints are illuminated by noncritical lighting. Flat paints in this situation tend to conceal joints. Evaluate carefully – weight, texture and sheen level of wall coverings/finishes. Conceal all joints adequately if wall-covering material is lightweight, glossy or lightly patterned or any combination of these three. All joints and interior angles shall be taped and finished with three coats of jointing material. Ensure joint compound is finished smooth and free of tool marks and ridges.

LEVELS OF FINISH

LEVEL 5

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Used where gloss or semi-gloss paints are specified. Also where critical lighting affects satin, flat or low-sheen paints. All joints and interior angles shall have tape embedded in joint compound. Apply a minimum of two separate coats of joint compound over all joints, angles, fastener heads and accessories. Finish all joint compound smooth and free of tool marks and ridges. Complete the work with proprietary surface preparations or, if required, skim coating to remove differential surface textures and porosity.

Boral Plasterboard - Lighting & Decoration The Facts

Tec

add a valuable member to your team

1800 811 222

Based in Melbourne,TecASSIST provides technical advice to builders, architects, contractors, distributors, engineers, regulators, home owners and students throughout Australia. Our friendly team comprising Geoff, Bernie and Danny are happy to assist with all your needs. It doesn't matter if you're a do-it-yourselfer, contractor, architect or engineer, our team can offer both practical and design input at all levels of the industry. When in doubt, ask! Telephone: 1800 811 222 Facsimile: 03 9645 1812 Email: [email protected]

Geoff Saxton, Len Pimm, Bernie Shalekoff and Danny Docherty.

SALES OFFICES Address

Telephone

Facsimile

QLD NSW SA VIC WA ACT TAS NT

733 Nudgee Rd Northgate 4013 3 Thackeray St Camellia 2142 119 Bedford St Gillman 5013 676 Lorimer St Port Melbourne 3207 53 Attwell St Landsdale 6065 7 Barrier St Fyshwick 2609 93 Albert Rd Moonah 7009 Cnr Coonawarra Rd & Mataram St Winnellie 0820

(07) 3215 2244 (02) 9638 0571 (08) 8240 8888 (03) 9214 2138 (08) 9400 2666 (02) 6280 4243 (03) 6278 9966 (08) 8984 4484

(07) 3215 2299 (02) 9638 5557 (08) 8341 1004 (03) 9646 1912 (08) 9302 2077 (08) 9280 5816 (03) 6278 9865 (08) 8984 3778

(03) 9214 2138

(03) 9645 2351

Export 676 Lorimer St Port Melbourne 3207

Boral Plasterboard - Lighting & Decoration The Facts

TecASSIST

Location

25

NOTES

Notes:

26

Boral Plasterboard - Lighting & Decoration The Facts

NOTES

Boral Plasterboard - Lighting & Decoration The Facts

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PB01686 02/05