Plastering

							Woodside General Learning Areas (6)

0611 PLASTERING

0611 PLASTERING

1 1.1

GENERAL AIMS

Responsibilities General: Provide plaster finishes as follows: - Resistant to impacts expected in use. - Free of irregularities. - Consistent in texture and finish. - Firmly bonded to substrates for the expected life of the application. - As a suitable substrate for the nominated final finish. Selections: Conform to the Selections. 1.2 CROSS REFERENCES

General General: Conform to the General requirements worksection. Associated worksections All sections of this specification are to be referred to as one document. 1.3 INTERPRETATION

Abbreviations General: For the purpose to this worksection the abbreviations given below apply. - CRF: Cement render – finish. - CRM: Cement render – medium. - CRS: Cement render – stronger. - CRW: Cement render – weaker. - GPF: Gypsum plaster – finish. Definitions General: For the purposes of this worksection the definitions given below apply. - Plastering: The process of coating the framing or solid surfaces of a building with a plastic material which hardens and then may be decorated or remain self-finished. - Substrate: The surface to which plaster is applied including lath or lath fixed to framing. - Base coat: A coat of a multi-coat plaster system which is applied before a finish coat, excluding any bonding treatment. - Bonding treatment: A treatment of a substrate which improves adhesion of a plaster system, not including a base coat. - Finish coat: The final coat of a multi-coat plaster system which may receive decoration or receive finishing treatment, including terms as follows: . Bedding coat. . Hardwall plaster. . Setting coat. . Skim coat. . Whiteset plaster. - Finishing treatment: The treatment applied to a finish coat which may include processes and results as follows: . Ornamental: Patterned surfaces achieved by working the hardening plaster with a trowel or other tool. . Plain: Even surfaces achieved by working the hardening plaster with a float or other tool. Page 138 of 405

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0611 PLASTERING

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. Sprayed: Textured surfaces achieved by projecting plaster onto a substrate using a purposedesigned machine also known as ‘tyrolean’. . Stippled: Textured surfaces achieved by working the hardening plaster with a stiff brush. . Thrown: Rough surfaces achieved by throwing plaster onto a substrate or pebbles onto a plastic plaster base. Control joints: Includes isolation joints, construction joints and crack control joints. Plaster: A mixture of binders, aggregate and water which are applied to substrates in a plastic state and dry and cure to a hard surface which may subsequently be decorated. . Cement: Plaster containing Portland cement as the principal binder. . Gypsum: Plaster containing hydrated or anhydrous calcium sulfate as the principal binder. Plastering system: One or more coats of plaster and associated treatments comprising some or all of the following in sequence: . Base coat 1 or 2. . Bonding treatment. . Finish coat. . Finishing treatment. Render, rendering: Plaster, plastering, usually single coat and usually cement:lime:sand. INSPECTION

1.4

Notice Inspection: Give sufficient notice so inspection may be made of the following: - Prototypes ready for inspection. - Substrates immediately before applying base coats. - Finish treatments before decoration. 1.5 SUBMISSIONS

Prototypes Plaster systems: Prepare prototypes of each plaster system complete with beads and other embedded items: - Size: 1200 x 2400 mm. 2 2.1 PRODUCTS MATERIALS AND COMPONENTS

Accessories Beads: To be metal proprietary sections manufactured to be fixed to substrates and/or embedded in the plaster to form and protect plaster edges and junctions. Lath: To be a proprietary product manufactured from raised expanded metal for use with plaster. 2 - Mass/unit area: ≥ 1.84 kg/m . - Material thickness: ≥ 0.70 mm. - Mesh size: 9.5 x 28.6 mm. Metallic-coatings: For beads or lath in cement plaster: To the Corrosion resistance and durability table. Admixtures Plasticizers or workability agents: Do not use in cement plasters. Aggregates Sand: To be fine, sharp, well-graded sand with a low clay content and free from efflorescing salts. Plaster for autoclaved aerated concrete General: To be a proprietary product manufactured for use with the wall system. Bonding products General: To be proprietary products manufactured for bonding cement-based plaster to solid substrates. Page 139 of 405

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0611 PLASTERING

Cement Standard: To AS 3972. - Type: GP. Colouring products General: To be proprietary products manufactured for colouring cement plaster. Integral pigment proportion:  5% by mass of cement. Cornice cement General: To be a proprietary product manufactured for use with the cornice. Cornices Cast plaster: To AS 2185 and AS 2590. Corrosion resistance and durability General: To the Corrosion resistance and durability table or proprietary products with metallic and/or organic coatings of equivalent corrosion resistance. Corrosion resistance and durability table – Low corrosivity category Situation
1

Metal lath, beads and embedded items

Internal External

Galvanize after fabrication 300 g/m Metallic-coated sheet Z275/AZ150 2 Galvanize after fabrication 300 g/m Stainless 316 Powder-coated aluminium

2

Minimum cement content (mix type) above dampproof course CRW CRW CRM

1

Situation - External: Includes external leaf and air spaces behind single skin brickwork or blockwork walls. - Internal: Includes building fabric protected from salt and moisture by vapour barriers, sarking, sheathing and building wraps. Corrosion resistance and durability table– Medium corrosivity category Situation
1

Metal lath, beads and embedded items

Internal External
1

Galvanize after fabrication 300 g/m Metallic-coated sheet Z275/AZ150 Stainless 316 Powder-coated aluminium

2

Minimum cement content (mix type) above dampproof course CRW CRM

Situation - External: Includes external leaf and air spaces behind single skin brickwork or blockwork walls. - Internal: Includes building fabric protected from salt and moisture by vapour barriers, sarking, sheathing and building wraps. Corrosion resistance and durability table– High corrosivity category Situation
1

Metal lath, beads and embedded items

Minimum cement content (mix type) above dampproof course CRW CRS

Internal (if plaster is painted) External
1

Galvanize after fabrication 300 g/m Metallic-coated sheet Z275/AZ150 Stainless 316 Powder-coated aluminium

2

Situation - External: Includes external leaf and air spaces behind single skin brickwork or blockwork walls. - Internal: Includes building fabric protected from salt and moisture by vapour barriers, sarking, sheathing and building wraps.

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0611 PLASTERING

Curing products General: To be proprietary products manufactured for use with the plaster system. Gypsum plaster General: To be a proprietary product containing calcium sulfate hemihydrate conforming to AS 2592 with additives to modify setting. Lime Limes for building: To AS 1672.1. Lime putty General: Prepare lime putty as follows: - Stand dry hydrate of lime to AS/NZS 1672.1 and water for 24 hours or more without drying out. - Stand quicklime and water for 14 days or more without drying out. Mixes General: Select a mix ratio to suit the conditions of application in conformity to the Mixes table. Measurement: Measure binders and sand by volume using buckets or boxes. Do not allow sand to bulk by absorption of water. Plaster mixing: Machine mix ≥ 3 < 6 minutes. Strength of successive coats: Ensure successive coats are no richer in binder than the coat to which they are applied. Mixes table – Cement render Mix type Substrate Upper and lower limits of proportions by volume Cement Lime Sand CRS - Single or multi-coat systems with integral finishing treatments - Base coats in multicoat systems with cement or gypsum finishes Second coat Internal Second coat External Dense and smooth concrete and masonry Regular clay or concrete masonry Lightweight concrete masonry and other weak substrates 1 1 1 1 1 1 0 0.5 0.5 1 1 2 1 2 1 2 3 4.5 4.5 6 6 9 6 9 5 6

CRM CRW

CRF CRF

Cement render base coats 1 1 Cement render base coats 1 1

Mix table - Gypsum finish coat Mix type Substrate

Upper and lower limits of proportions by volume Gypsum Cement Lime Sand 1.5 2 -

Gypsum finish coats

GPF

Cement render base coats 1 1

Dash coat Dash coat: 1:2 cement : sand. Control joint products General: To be proprietary products manufactured for use with the plastering system and to accommodate the anticipated movement of the substrates and/or the plaster. Water General: To be clean and free from any deleterious matter.

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Woodside General Learning Areas (6)

0611 PLASTERING

3 3.1

EXECUTION PREPARATION

Substrates General: Ensure substrates have: - Any deposit or finish which may impair adhesion of plaster cleaned off. - If framed or discontinuous, support members in full lengths without splicing. - If solid or continuous, excessive projections hacked off and voids and hollows filled with plaster stronger than the first coat and not weaker than the substrate. Absorbent substrates: If suction is excessive, control it by dampening but avoid over-wetting and do not plaster substrates showing surface moisture. Dense concrete: If not sufficiently rough to provide a mechanical key, roughen by scabbling or the like to remove 2 mm of the laitance and expose the aggregate then apply a bonding treatment. Painted surfaces: Remove paint and hack the surface at close intervals. Untrue substrates: If the substrate is not sufficiently true to ensure conformity with the thickness limits for the plaster system or has excessively uneven suction resulting from variations in the composition of the substrate, apply additional coats without exceeding the thickness limits for the substrate or system. Beads Location: Fix beads as follows: - Angle beads: At all external corners. - Drip beads: At all lower terminations of external plaster. - Movement control beads: At all movement control joints. - Stop beads: At all terminations of plaster and junctions with other materials or plaster systems. Joints in beads: Use dowels to maintain alignment. Mechanical fixing to substrate: ≤ 300 mm centres. Bonding treatment General: If bonding treatment is required, throw a wet mix onto the background as follows: - Cement plaster: 1 part cement to 2 parts sand. - Gypsum plaster: 1 part gypsum to 2 parts sand. Curing: Keep continuously moist for ≥ 5 days and allow to dry before applying plaster coats. Thickness: From ≥ 3 < 6 mm. Embedded items General: If there are water pipes and other embedded items, sheath them to permit thermal movement. Ensure embedded items conform to the Corrosion resistance and durability table. Lath Location: - Chases: To all chases or recesses fix metal lath extending ≥ 75 mm beyond each side of the chase or recess. - Fit metal lath to masonry and concrete substrates - Metal and other non-porous backgrounds: Fix metal lath to provide a key. Installation: - General: Run the long way of the mesh across supports with strands sloping downwards and inwards from the intended face of the plaster. - Fixing: Mechanically fix at centres of 150 mm or less. - Laps: Tie with 1.25 mm galvanized wire ≤ 150 mm. Do not stop edges of sheets at corners but bend around. - On solid substrates: Space the lath 5 mm or more clear of the substrate. - Support spacing: ≤ 400 mm.

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Woodside General Learning Areas (6)

0611 PLASTERING

3.2

APPLICATION

Plastering Base coats: Scratch-comb each base coat in two directions when it has stiffened. Metal lath: Press the plaster through the apertures of expanded metal lath and wings of beads. Finishing treatments Plain: - Bag: To be a finish mainly free from sand by rubbing the finish coat with a Hessian pad when it has set firm. - Carborundum stone: To be a smooth finish free from sand by, rubbing the finish coat with a fine carborundum stone when it has set hard. - Foam float: To be an even surface by a wood or plastic floating the finish coat on application and finishing with a foam float to a fine sand textured finish. - Steel trowel: To be a smooth dense surface by steel trowelling which is not glass-like and is free from shrinkage cracks and crazing. - Wood or plastic float: To be an even surface by wood or plastic floating the finish coat on application. Incidental work General: Return plaster into reveals, beads, sills, recesses and niches. Plaster faces, ends, and soffits of projections in the substrate, such as string courses, sills, pilasters and corbels. Run throating on soffits of external projections neatly finished. Trim around openings. Plaster exposed inside of built-in cupboards. Joining up General: If joining up is required, ensure joints will be imperceptible in the finished work after decoration. Control joints General: Provide joints in the finish to coincide with control joints in the substrate. Ensure that the joint in the substrate is not bridged during plastering. - Depth: Extend the joint right through the plaster and reinforcement to the substrate. - Width: 3 mm, or the same width as the substrate joint, whichever is greater. Damp-proof courses: Do not continue plaster across damp-proof courses. Plastering on metal lath: Provide movement joints to divide the plastering area into rectangular panels 2 ≤ 10 m . V-joints: Provide V-joints, cut right through the plaster to the substrate, at the following locations: - Abutments with metal door frames. - Abutments with other finishes. - Junctions between different substrates. Plaster thickness General: Conform to the Plaster thickness table. Plaster thickness table Plaster Application Upper limit of thickness (mm) Single coat systems Cement render base coats and cement or gypsum finish coats On smooth dense 12 concrete and masonry On clay and concrete 15 masonry and other substrates Multi-coat systems Base coat(s) 10 Finish coat 4

13

4

Temperature General: If the ambient temperature is ≤ 10ºC or ≥ 30ºC ensure that the temperature of mixes, substrates and reinforcement are, at the time of application, ≥ 5ºC or ≤ 35ºC. Page 143 of 405

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0611 PLASTERING

3.3

TOLERANCES

General Tolerances: Conform to the Tolerances table. Tolerances table Property Features : Verticality in 2000 mm Features: Horizontality in 2000 mm Soffits: Horizontality in 2000 mm Walls: Verticality in 2000 mm Walls: Flatness in 2000 mm
1 2 1

Tolerance criteria: Permitted deviation (mm) 2 2 4 4 3

Features: Conspicuous horizontal or vertical lines including external corners, parapets, reveals, heads, sills, movement control joints and mouldings. 2 Flatness: Measured under a straightedge laid in any direction on a plane surface.

3.4

COMPLETION

Cornices General: Accurately cut and mitre corners. Match and align ornament. Unless required, or full lengths are not available, do not make butt joints in the length of a cornice. Installation: Butter edges, mitres and joins for the full length of the cornice with adhesive: Mechanical fixing: If projection across ceiling ≥ 400 mm, provide additional mechanical fixing: - Fixing centres: ≤ 600 mm. Curing General: Prevent premature or uneven drying out and protect from the sun and wind. Keeping moist: If a proprietary curing agent is not used, keep the plaster moist as follows: - Base coats and single coat systems: Keep continuously moist for 2 days and allow to dry for 5 days before applying further plaster coats. - Finish coats: Keep continuously moist for 2 days. 4 4.1 SELECTIONS SCHEDULES Finishing Tool Wood float and sponge Surface Making good where directed on site, damaged, out of line or defective edges to raft External brick/masonry walls to be rendered.

CEMENT RENDER: Type Of Finish Sand-natural onecoat Sand-natural twocoat PLASTER: Type Of Finish Hard Plaster

Wood float and sponge

Finishing Tool Steel trowel

Surface Making good at new openings and wall removals. Refer Drawings

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