SECTION PORTLAND CEMENT PLASTER (STUCCO) WITH ACRYLIC FINISH

Transcription

1 SECTION PORTLAND CEMENT PLASTER (STUCCO) WITH ACRYLIC FINISH PART I - GENERAL 1.01 SECTION INCLUDES A. Building paper B. Lath and accessories C. Plaster materials D. Acrylic finish E. Exterior Portland cement plasterwork (stucco) on metal lath on unit masonry, for new walls, infilling areas at openings to be infilled, patching of existing, and repairs RELATED SECTIONS A. Section Sealants and their installation REFERENCES A. Workmanship and installation shall be performed in accordance with: 1. Building code (s) in effect. 2. Manufacturer s requirements. 3. ASTM C1063 Lathing and Furring for Portland Cement Plastering. 4. ASTM C926 Standard Specifications for Application of Portland Cement-Based Plaster SUBMITTALS A. Submit the following in accordance with Section 01300: 1. At least (1) 24 inch square samples of plaster with acrylic finish in color (s) and textures (s) specified, for approval. Do not proceed with work until samples have been approved. B. Product Data C. Shop Drawings: show locations and installation of control and expansion joints including plans, elevations, sections, details of components, and attachment to other work QUALITY ASSURANCE A. Qualifications 1. Applicator must be qualified in the workmanship of plastering and must be able to show completed work of equal scope. 2. Contractor/Applicator shall have successfully completed (3) contracts in the past (3) years, each having a construction value of $50,000 or greater. 3. Applicator shall be approved by the manufacturer of the acrylic finish to apply that material. B. Pre-Installation Conference: The Construction Manager may schedule a pre-installation conference with the Owner, Architect and plastering subcontractor, to review the work of this Section. Attendance by this subcontractor will be mandatory DELIVERY, STORAGE AND HANDLING A. Deliver materials in original containers with labels intact and legible. Store and protect materials furnished PROJECT/SITE CONDITIONS A. Environmental Requirements

2 1. Cement Plaster a. Cold Weather 1. Do not use frozen materials. 2. Do not apply cement plaster to frozen surfaces or surfaces containing frost. 3. Do not mix materials or apply cement plaster when ambient temperature is less than 40 degrees F. b. Hot Weather 1. Protect cement plaster from uneven and excessive evaporation during hot, windy, or dry weather. 2. In hot, windy or dry weather, the cement plaster should be moistened down and then covered with a single sheet of clear polyethylene plastic. 2. Acrylic Finish a. Protect cement plaster from all forms of precipitation during the application and the setting/curing period of finish coat. Ensure that the finish is fully set prior to removing protective covering. b. Do not use frozen materials or materials that have been frozen. c. Do not apply acrylic finish when ambient temperature is less than 40 degrees F. d. Do not apply acrylic finish unless the temperature has been 40 degrees F for at least 24 hours before the application. e. Do not apply acrylic finish when there is any form of precipitation. f. Do not apply acrylic finish to brown coat of cement plaster if sun is directly on the wall surface and temperature is 75 degrees F. Work in shade whenever possible. B. Comply with ASTM C 926 requirements C. comply with manufacturer s written recommendations for environmental conditions for applying finishes. PART 2 - PRODUCTS 2.01 MATERIALS A. Building Paper: ASTM D226, non-perforated, 15 pound. B. Metal Lath: ASTM C847, with ASTM A 653/A 653M, G60 (Z180), hot-dip galvanized zinc coating, self-furring, not less than 3.4 pounds per square yard. Diamond metal lath. Paper Backing: FS UU-B-790, Type 1, Grade D, Style 2 vapor-permeable paper (provide paper-backed lath unless otherwise indicated) C. Accessories 1. Shapes used as grounds shall be sized and dimensioned to provide required plaster thicknesses. 2. Weather-exposed accessories shall be fabricated from zinc alloy materials. 3. Profile of casing beads and control joints shall provide lip flange and/or embedment section; #75 or equal - U.S.G. or Keene s. 4. Corner reinforcing shall be galvanized welded wire equal to Corneraid (Stockton) and fabricated for full embedment in the brown coat. 5. Provide standard trim items including control joints, casing beads, exterior corner beads, and base screeds. D. Plaster Materials 1. Portland Cement: ASTM C150, Type II. 2. Masonry Cement: ASTM C91, Type N 3. Lime: ASTM C 206, Type S; or ASTM C 207, Type S 4. Sand Aggregate: ASTM C897, color for job-mixed finish coats in color to match color selected. 5. Admixtures: Acrylic liquid admix equal to Acryl 60 (Thoro System Products, Inc.) 6. Acrylic Finish: Factory mixed 100 percent pure acrylic finish with aggregate and integral color (e.g. Dryvit, Parex/Insulcrete, Senergy, Sto, Thoro, U.S.G., Ful-O-Mite, Finestone or approved equal)

3 a. Color (s): color to match STO 3003 Amarilla (Custom color (s) as required) b. Texture: to match existing. E. Miscellaneous Materials 1. Water: Clean and free of substances harmful to plaster, lath or accessories 2. Fiber: 1/2 inch long chopped fiberglass strands, alkali-resistant glass or polypropylene fibers, free of contaminants, manufactured for use in Portland cement plaster. 3. Bonding Compound: ASTM C Steel Drill Screws: For metal-to-metal fastening, ASTM C 1002 or ASTM C 954, as required by thickness of metal being fastened; with pan head that is suitable for application; in lengths required to achieve penetration through joined materials of no fewer than three exposed threads. 5. Fasteners for attaching metal lath to substrates: Complying with ASTM C Wire: ASTM A 641/A 641M, Class 1 zinc coating, soft temper, not less than inch (1.21-mm) diameter, unless otherwise indicated MIXES A. General 1. Comply with ASTM C 926 for applications indicated. a. Fiber content: Add fiber to base-coat mixes after ingredients have mixed at least two minutes. Comply with fiber manufacturer s written instructions for fiber quantities in mixes, but do not exceed 1 lb of fiber/cu yd. (0.6 kg of fiber/cu m) of cementitious materials.) 2. Base-Coat mixes for use over metal lath: Scratch and brown coats for three-coat plasterwork as follows: a. Portland Cement Mixes: i. Scratch coat: For cementitious material, mix 1 part Portland cement and ¾ to 1-1/2 parts lime. Use 2-1/2 to 4 parts aggregate per part of cementitious material. ii. Brown coat: For cementitious material, mix 1 part Portland cement and ¾ to 1-1./2 parts lime. Use 3 to 5 parts aggregate per part of cementitious material, but not less than volume of aggregate used in scratch coat. 3. Job-Mixed Finish-Coat Mixes: a. Portland cement mix: for cementitious materials, mix 1 part Portland cement and ¾ to 1-1/2 parts lime. Use 1-1/2 to 3 parts aggregate per part of cementitious material. b. Plastic cement mix: 1 part plastic cement and 1-1/2 to 3 parts aggregate. 4. Factory-prepared Finish-coat mixes: acrylic-based finish coatings, comply with manufacturer s written instructions. 5. Accurately proportion materials for each batch using measuring devices of known volume. PART 3 - EXECUTION 3.01 EXAMINATION A. Installer/Applicator must examine the areas and conditions under which the work is to be performed and notify the Contractor in writing of conditions detrimental to the proper and timely completion of the work. Do not proceed with installation/application until unsatisfactory conditions have been corrected in a manner acceptable to the installer/applicator

4 B. Concrete and masonry surfaces must be free of dust, loose particles, oil, and other foreign matter which would affect a bond of cement plaster. C. Protect adjacent work from soiling, spattering, moisture deterioration, and other harmful effects caused by plastering. D. Prepare solid substrates for plaster that are smooth or that do not have the suction capability required to bond with plaster according to ASTM C INSTALLATION/APPLICATION A. General 1. Secure building paper to sheathing shingle style lapping edges and ends not less than 3 inches. Apply double layer over plywood sheathing. 2. Attach lath to framing or substrate according to ASTM C , lapping sides not less than 1/2 inch and ends not less than one inch. 3. Attach accessories level, plumb and true, and to create a proper screed and depth for the cement plaster. a. Install control joints to create panels relatively square, not larger than 144 square feet and with no dimension exceeding 18 feet or a length to width ratio of 2-1/2:1. Verify joint placement with Architect. B. Installing Metal Lath 1. Expanded-Metal lath: Install according to ASTM C 1063 a. partition framing and vertical furring: install flat diamond-mesh lath. C. Installing Accessories 1. Install according to ASTM C 1063 and at locations indicated on Drawings. 2. Reinfocement for External Corners: a. Install lath-type, external-corner reinforcement at exterior locations b Install cornerbead at interior and exterior locations. 3. Control Joints: Install control joints per industry standards and as identified on drawings for visual effect. a. As required to delineate plasterwork into areas (panels) of the following maximum sizes: a. Vertical Surfaces: 144 sq. ft. (13.4 sq. m) b. Horizontal and other non-vertical surfaces: 100 sq. ft. (9.3 sq. m) b. At distances between control joints of not greater than 18 feet (5.5 m) o.c. c. As required to delineate plasterwork into areas (panels) with length-to-width ratios of not greater than 2-1/2:1. d. Where control joints occur in surface of construction directly behind plaster. e. Where plasterwork areas change dimensions, to delineate rectangular-shaped areas (panels) and to relieve the stress that occurs at the corner formed by the dimension change. D. Plaster Application 1. General: Comply with ASTM C Bonding compound: apply on unit masonry plaster bases. 3. Walls; Base-coat mixes for use over metal lath: Scratch and brown coats for threecoat plasterwork, on masonry, on concrete, ¾ thickness (verify to match existing). a. Portland cement mixes b. Portland and plastic cement mixes 4. Plaster Finish Coats: apply to provide finish to match existing 5. Acrylic-Based Finish Coatings: Apply coating system, including primers, finish coats, and sealing topcoats, according to manufacturer s written instructions. 6. Concealed Exterior Plasterwork: Where plaster application will be used as a base for adhered finishes, omit finish coat. D. Plaster Repairs

5 3.03 CLEANING 1. Repair or replace work to eliminate cracks, dents, blisters, buckles, crazing and check cracking, dry outs, efflorescence, sweat outs, and similar defects and where bond to substrate has failed. A. Remove spattering of plaster and acrylic finish from other finished surfaces, paving and walks. END OF SECTION