Specification Section 09 24 00 - Portland Cement Plastering.pdf

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SECTION 09 24 00

PORTLAND CEMENT PLASTERING

PART 1 - GENERAL

1.1 DESCRIPTION

A. This Section specifies lathing and Portland cement-based plaster / stucco.

1.2 RELATED WORK

A. Section 05 40 00, COLD-FORMED METAL FRAMING: Steel framing members for attachment of plaster bases

B. Section 09 06 00, SCHEDULE FOR FINISHES: Room Finish Schedule and

Color.

1.3 TERMINOLOGY

A. Definitions and description of terms shall be in accordance with

ASTM C11, ASTM C926, ASTM C1063, and as specified.

B. Self-Furring Lath: Metal plastering bases having dimples or crimps designed to hold the back plane of the lath 6 to 10 mm (1/4 to

3/8 inch) away from the plane of the solid backing.

C. Solid Backing or Solid Bases: Concrete, masonry, sheathing, rigid insulation, and similar materials to which plaster is directly applied.

D. Wet Areas: Areas of a building where cyclic or continuous exposure to very humid or wet conditions, or in which a dew point condition may occur in the plaster.

1.4 SUBMITTALS

A. Submit in accordance with Section 01 33 23, SHOP DRAWINGS, PRODUCT

DATA, AND SAMPLES.

B. Manufacturer's Literature and Data:

1. Accessories for plaster, each type.

2. Metal plastering bases, each type.

3. Fasteners.

4. Bonding compounds, including application instructions.

5. Admixtures, including mixing and application instructions.

C. Samples:

1. Accessories for plaster, each type, not less than 152 mm (6 inches) long.

2. Panel showing finish coat 152 to 305 mm (6 by 12 inches) minimum.

D. Installers qualifications.

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1.5 DELIVERY, STORAGE AND PROTECTION

A. Deliver manufactured materials in the manufacturers’ original unbroken packages or containers which are labeled plainly with the manufacturers’ names and brands. Keep cementitious materials dry and stored off the ground, under cover, and away from sweating walls and other damp surfaces until ready for use.

1.6 PROJECT CONDITIONS

A. Maintain work areas for interior work at a temperature of not less than

4 degrees C (40 degrees F) for not less than 48 hours prior to application of plaster, during application of plaster and one week after plaster has set or until plaster has dried.

B. Do not apply exterior plaster when the ambient temperature is less than 4 degrees C (40 degrees F), or when a drop in temperature below

4 degrees C (40 degrees F) is expected within 24 hours after application.

C. Do not apply plaster to frozen surfaces or surfaces containing frost.

D. Do not use frozen materials in the mix.

E. Protect plaster coats against freezing for a period of not less than

24 hours after application.

1.7 QUALITY ASSURANCE

A. Installers Qualifications: Work shall be performed by installer having a minimum of three (3) years’ experience for work relating to this

Section. Submit installer qualifications.

1.8 APPLICABLE PUBLICATIONS

A. The publications listed below form a part of this specification to the extent referenced. The publications are referenced in the text by basic designation only.

B. ASTM International (ASTM):

A653/A653M-20...........Steel Sheet, Zinc-Coated (Galvanized) or Zinc-

Iron Alloy-Coated (Galvannealed) by the Hot-Dip

Process

A1064/A1064M-18a........Carbon-Steel Wire and Welded Wire

Reinforcement, Plain and Deformed, for Concrete

C11-18b.................Terminology Relating to Gypsum and Related

Building Materials and Systems.

C91/C91M-18.............Masonry Cement

C150/C150M-20...........Portland Cement

C206-14.................Finishing Hydrated Lime

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C207-18.................Hydrated Lime for Masonry Purposes

C260/C260M-10a(2016)....Air Entraining Admixtures for Concrete.

C847-18.................Metal Lath

C897-15(2020)...........Aggregate for Job-Mixed Portland Cement Based

Plasters

C926-20.................Application of Portland Cement-Based Plaster

C932-06(2019)...........Surface-Applied Bonding Compounds for Exterior

Plastering

C933-18.................Welded Wire Lath

C979/C979M-16...........Pigments for Integrally Colored Concrete

C1002-18................Steel Self-Piercing Tapping Screws for the

Application of Gypsum Panel Products or Metal

Plaster Bases to Wood Studs or Steel Studs

C1063-19a...............Installation of Lathing and Furring to Receive

Interior and Exterior Portland Cement-Based

Plaster

E90-09(2016)............Test Method for Laboratory Measurement of

Airborne Sound Transmission Loss of Building

Partitions and Elements

E119-20.................Test Methods for Fire Tests of Building

Construction and Materials

E413-16.................Classification for Rating Sound Insulation

C. Commercial Item Description (CID):

A-A-55615-95(R2006).....Shield, Expansion (Wood Screw and Lag Bolt

Self-Threading Anchors)

PART 2 - PRODUCTS

2.1 METAL PLASTERING BASES

A. Expanded Lath:

1. ASTM C847, galvanized except as modified by ASTM C1063 and this specification. Self-furring where applied over solid backing.

2. Flat diamond mesh weighing not less than 1.8 kg per square meter

(3.4 pounds per square yard).

B. Stucco Mesh: Flat expanded diamond mesh pattern, with openings approximately 38 by 75 mm (1-1/2 by 3 inches), weighing not less than

1.9 kg per square meter (3.6 pounds per square yard), with backing as specified.

C. Wire Lath:

1. Zinc-coated (Galvanized).

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2. Welded-Wire Lath: ASTM C933, with backing as specified.

3. Self-furring where applied over solid backing.

D. Building Paper Backing for Metal Plastering Bases:

1. Backing Attached to Lath: As specified in ASTM C933.

2. Vapor-Permeable Backing: Fed. Spec. UU-B-790, Type I, Grade D.

3. Water-Resistant Backing: Fed. Spec. UU-B-790, Type I, Grade B.

2.2 ACCESSORIES FOR CEMENT PLASTER / STUCCO

A. Provide accessories that are roll-formed galvanized steel, except that cornerite and strip lath that are formed from steel sheets with manufacturer’s standard galvanized coating.

B. Provide welded-wire corner reinforcements of galvanized 1.4 mm

(17 gauge) steel wire conforming to ASTM A1064/A1064M.

C. Provide furring, including hangers, bolts, inserts, clips, fastenings, and attachments of number, size, and design to develop the full strength of the members.

D. Control Joints: ASTM C1063, zinc-coated (galvanized) steel;

one-piece-type, folded pair of unperforated screeds in M-shaped configuration; with perforated flanged and removable protective tape on plaster face of control joint.

E. Foundation Weep Screed: Fabricated form hot-dip galvanized-steel sheet, ASTM A653/A653M, G60 (Z180) zinc coating.

F. Cornerite: Fabricated from metal lath with ASTM A653/A653M, G60 (Z180), hot-dip galvanized-zinc coating.

G. External- (Outside-) Corner Reinforcement: Fabricated from metal lath with ASTM A653/A653M, G60 (Z180), hot-dip galvanized-zinc coating.

H. Cornerbeads: Fabricated from zinc-coated (galvanized) steel.

1. Smallnose cornerbead with expanded flanges; use unless otherwise indicated on Construction Documents.

2. Smallnose cornerbead with expanded flanges reinforced by perforated stiffening rib; use on columns and for finishing unit masonry corners.

I. Casing Beads: Fabricated form zinc-coated (galvanized) steel;

square-edged style; with expanded flanges.

2.3 FASTENERS

A. Tie, wire, screws, staples, clips, nails, and other fasteners

ASTM C1063, except as otherwise specified.

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B. Provide fasteners for securing metal plastering bases having heads, or inserted through washers large enough to engage two (2) strands (two

(2) on each side of screw) of the metal plastering base.

C. Screws: ASTM C1002.

D. Expansion Shields: CID A-A-55615, of the Type and Class applicable.

2.4 CEMENT

A. Portland: ASTM C150/C150M, Type I.

B. Masonry: ASTM C91/C91M, Type N.

2.5 LIME

A. ASTM C206, Type S; or ASTM C207, Type S.

2.6 AGGREGATES (SAND)

A. ASTM C897, graded as required to suit texture of finish specified.

2.7 BONDING AGENT

A. ASTM C932.

2.8 FACTORY-PREPARED FINISH COAT FOR CEMENT PLASTER / STUCCO)

A. Factory-prepared dry blend of materials, integrally colored, designed for exterior finish coat application.

B. Pigments: ASTM C979/C979M, lime proof mineral oxide.

C. Particle Size: Not more than 35 percent, by weight of all ingredients, including cement, aggregate, hydrated lime, admixture and coloring pigment is to pass a number 100 sieve.

2.9 ADMIXTURES

A. Air Entrainment: ASTM C260/C260M.

PART 3 - EXECUTION

3.1 METAL PLASTERING BASES (LATH) LOCATIONS

A. Where plaster is required on solid concrete or masonry bases, metal plastering bases are not required, unless shown on the Construction

Documents. Where shown use wire lath or stucco mesh.

B. Where metal plastering bases are used as a base for exterior cement plaster over wall sheathing, provide wire lath or stucco mesh with water-resistant backing.

3.2 APPLYING METAL PLASTERING BASES

A. In accordance with ASTM C1063, except as otherwise specified or indicated on Construction Documents.

B. Form true surfaces, straight or in curves where shown on Construction

Documents, without sags or buckles and with long dimension of lath at right angles to direction of supports.

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C. Terminate lath for ceiling or soffit construction at casing bead

(floating angle construction) at perimeter angles between walls and ceilings or soffits.

D. Lath with backing shall be applied to produce a paper-to-paper and metal-to-metal lap at ends and sides of adjacent sheets, whether full sheets or less than full sheets are provided:

1. Lap backing 50 mm (2 inches) for both horizontal and vertical laps.

2. Install horizontal laps in a ship lap fashion to conduct water to the outside and over flashing or waterproofing.

E. Do not install continuous metal plastering bases through expansion and control joints. Terminate at each side of joint.

F. Attach lath directly to masonry and concrete with hardened nails, power-actuated drive pins or other approved fasteners. Install fasteners at dimples or crimps only.

G. Wood plugs will NOT be acceptable.

3.3 INSTALLING PLASTERING ACCESSORIES

A. Install accessories in accordance with ASTM C1063, except as otherwise specified.

1. Set plastering accessories plumb, level, and true-to-line, neatly mitered at corners and intersections, and securely attach to supporting surfaces.

2. Install in one (1) piece, within the limits of the longest commercially available lengths.

B. Corner Beads: External-corner reinforcement or corner bead at exterior corners, as required to establish grounds, and where shown on

Construction Documents.

C. Strip Lath:

1. Install centered over joints between dissimilar materials, such as hollow tile, brick, concrete masonry units, concrete, and joints with expanded lath on framing or furring, where both such surfaces are required to be plastered and are in contact with each other in same plane, except where expansion joints and casing beads are required.

2. Wire tie or fasten strip lath to base along both edges at not over 152 mm (6 inches) on centers.

D. Casing Beads:

1. Provide at locations where shown on Construction Documents and at following locations where plaster terminates to provide finish trim:

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a. Against non-plastered surfaces such as masonry and // concrete.

b. Against trim of steel frames and trim of other materials and equipment, except where trim overlaps plaster.

c. Around perimeter of openings except where edge is covered by flanges. Locate to conform to dimensions shown on Shop Drawings.

d. Where plaster for new walls or furring (vertical or horizontal) terminates against existing construction.

e. Both sides of expansion and control joints unless shown otherwise on Construction Documents.

2. Provide at perimeter angles between walls and ceilings so as to provide floating angle (unrestrained) construction in accordance with ASTM C1063.

E. Cornerites:

1. Provide at interior corners of walls, partitions, and other vertical surfaces to be plastered, except where lath is carried around angle.

2. Fasten only as necessary to retain position during plastering.

3. Omit cornerites at junction of new plastered walls with existing plastered walls at locations where casing beads are specified.

F. Control Joints:

1. Where control joints are placed parallel to framing members, install joints within 101 mm (4 inches) of the framing member.

2. Install control joints only to the edges of abutting sheets of lath so that the lath is not continuous or tied across the joint.

3. Extend joints the full width and height of the wall or length of soffit/ceiling plaster membrane.

3.4 SURFACE PREPARATION OF SOLID BASES

A. Surfaces that are to receive plaster shall be prepared and conditioned in accordance with ASTM C926, except as otherwise specified.

B. New surfaces of masonry and concrete:

1. Remove projections and clean concrete surface of form oil.

2. Fill depressions, holes, cracks and similar voids flush with

Portland-cement plaster to provide substrate within the tolerance specified in ASTM C926.

3. Use bonding agent.

4. Cover with self-furring lath where required to keep the total plaster thickness as specified in Table 4 of ASTM C926.

C. Existing surfaces of concrete and masonry:

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1. Clean surface of dirt and other foreign matter which will prevent bond.

2. Apply dash bond coat or bonding agent as specified herein.

3. Where existing surfaces have a coating such as paint or bituminous waterproofing apply metal plastering base as indicated.

3.5 PORTLAND-CEMENT-BASED PLASTER

A. Provide Portland-cement-based plaster where cement plaster / stucco is shown and specified, and as follows:

1. Three-Coat work shall be used over all metal plastering bases, with or without solid backing.

2. Two-Coat work may only be used over solid bases conforming to requirements of Paragraph, SURFACE PREPARATION OF SOLID BASES.

B. Proportion, mix, and apply plaster in accordance with ASTM C926, except as otherwise specified.

1. Provide air-entrained plaster for all exterior work.

2. Provide coloring pigments for finish coat.

3. Factory-Prepared Finish Coat: Add water, mix, and apply as specified by manufacturer.

4. Color:

a. As specified in Section 09 06 00, SCHEDULE FOR FINISHES.

5. Finish coat is to have a sand float finish.

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