SPECIAL SPECIFICATION 2242 LATH, STUCCO AND PLASTER

Transcription

1 2004 Specifications CSJ: SPECIAL SPECIFICATION 2242 LATH, STUCCO AND PLASTER 1.1 DESCRIPTION A. Section Includes 1. This Item shall govern for the installation of lath, stucco and plaster particularly at metal wall flashing locations and interior work plaster reconstruction as indicated on the plan drawings. B. Supply and install all laths and plaster work or plaster work only as shown on drawings and as specified herein. C. Coordination: Work herein requires coordination with trades whose work connects with, is affected, or concealed by lathing and plastering. Before proceeding, make certain all required inspections have been made. D. Inspection: Inspect surfaces to receive lath and plaster before starting work and do not start until surfaces are acceptable. Starting work under this section implies acceptance of surfaces. E. Delivery and Storage: Deliver all manufactured materials in original packages bearing manufacturerʼs name and brand. Use only one brand of each material throughout job. Store materials in dry areas. F. General Requirements: Comply with all applicable requirements of the Texas Bureau of Lathing and Plastering, Inc. Manuel for Lathing and Plastering, and Texas Lathing and Plastering Contractorʼs Association Standards, except where more stringent requirements are called for herein or in local building codes. Do all cutting and patching required to accommodate work of other trades. G. Submittals: Product Data for each product specified and Samples for each type of finish indicated. H. Fire-Test-Response Characteristics: Where indicated, provide materials and construction identical to those tested per ASTM E MATERIALS A. Expanded Type, diamond shaped, copper bearing steel, weighing 3.4#/Sq. Yd., galvanized

2 B. Installation: Apply to true surfaces, straight without warps or buckles, long dimension of lath at right angles to supports. Secure lath to supports at 6 inch intervals. Secure the side laps to supports and tie between supports. Lap 1/2 at sides and 1 at ends; and laps must be staggered and supported. No sheet ends allowed less than one support distant from any angle or corner, bend sheets for internal corners or use corner laths. Install strip lath over joints between dissimilar base materials where surfaces lie in the same plane and where base materials cannot be effectively bonded together. C. Accessories: 1. Install all accessories to plumb, true and level lines, and backing plates as located by the trade furnishing these items. D. Manufacturers: Subject to compliance with requirements, provide products by one of the following or equal: 1. Expanded-Metal Lath: a. California Expanded Metal Products Co. b. Dietrich Industries, Inc. c. National Gypsum Co. d. United States Gypsum Co. e. Western Metal Lath Co. 2. Metal Accessories: a. California Expanded Metal Products Co. b. Metalex (Keene Products). c. National Gypsum Co. d. United States Gypsum Co. e. Western Metal Lath Co. 3. Stucco: a. California Stucco Products Corp. b. Florida Stucco Corp. c. Highland Stucco. d. IPA Systems, Inc. e. United States Gypsum Co. E. Ceiling Support Components: ASTM C Wire for Hangers and Ties: ASTM A 641 Class 1 zinc coating, soft temper. 2. Rod Hangers: Mild steel, zinc coated

3 3. Flat Hangers: Mild steel, zinc coated or protected with rust-inhibitive paint. 4. Channels: Cold-rolled steel, minimum inch- thick base (uncoated) metal and 7/16-inch- wide flanges, and as follows: a. Carrying Channels: 1-1/2 inches deep, 475 lb/1000 feet. b. Furring Channels: 3/4 inch deep, 300 lb/1000 feet. c. Finish: ASTM A 653, G60 hot-dip galvanized. F. Vertical Metal Furring: Comply with the following: 1. Protective Coating: ASTM A 653, G40 hot-dip galvanized coating. 2. Protective Coating: Manufacturer's standard corrosion-resistant coating. 3. Channel Furring and Braces: Cold-rolled steel, minimum inch- thick base (uncoated) metal and 3/4-inch- deep-by-7/16-inch- wide flanges, 300 lb/1000 feet. 4. Hat Channels: Hat-shaped screwable furring channels, 7/8 inch deep, formed from Zinc-coated (galvanized) steel sheet, minimum inch thick, Grade Z-Furring Members: Screw-type Z-shaped furring members formed from minimum inch- thick, zinc-coated (galvanized) steel sheet. 6. Furring Brackets: Serrated-arm type, minimum inch- thick base (uncoated) metal, adjustable from 1/4- to 2-1/4-inch wall clearance for channel furring. 7. All metal laths, corner beads, anchors and accessories to be Galvanized Steel Components: Fabricated from zinc-coated (galvanized) steel sheet complying with ASTM A 653, G40 minimum coating designation. 8. Zinc-Alloy Components: ASTM B 69, 99 percent pure zinc. 9. Metal Cornerbeads: Fabricated from zinc-coated (galvanized) steel. 10. Corner Laths: As specified for expanded metal lath, 3 legs bent to a 105% corner, weighing 40#/1000 L.F.. Install at interior angles and where one or both abutting surfaces are metal lath. Corner laths are not required where metal is continued around corner at junction of walls and where ceiling lath turns down wall. 11. Casing Beads: #66 Type, expanded metal flange, galvanized, depth as required by plaster thickness, weighing approximately 289#/100 L.F. for 3/4 and 7/8 Types. Install at all edges of plaster, continuously, including where plaster butts all other materials, by securing to lath at 6 o.c. 12. Strip Reinforcement: Smooth-edge strips of expanded-metal lath fabricated from uncoated or zinc-coated (galvanized) steel sheet. Provide cornerite or stripite form as required

4 13. Casing Beads: Square-edged style, fabricated from aluminum coated with clear plastic, with short or expanded flanges to suit kinds of plaster bases indicated. 14. Control Joints: Aluminum coated with clear plastic and adjustable for joint widths from 1/8 to 5/8 inch. 15. Control and Expansion Joints: 7/8 ground, expanded metal flanges, galvanized minimum 28 gauge, (Type #15). 16. Steel Drill Screws: ASTM C 1002 & ASTM C 954 G. Water for Mixing and Finishing Plaster: Potable and free of substances capable of affecting plaster set or of damaging plaster, lath, or accessories. H. Lime: ASTM C 206, Type S; ASTM C 207, Type S. I. Bonding Agent: ASTM C 932. J. Expanded-Metal Lath: ASTM C 847, diamond mesh, flat or self-furring configuration as indicated, and with minimum 3.4-lb/sq. yd. weight. K. Waterproofing: Application procedures for Self-adhesive Water-proofing membrane will be to apply coating by brush, roller, spray, or other applicators according to manufacturer's written instructions. Exterior wall application only. L. Scratch Coat: 1 part Portland Cement, 4 parts sand and hydrated lime equal to 25% of volume of cement. Apply with sufficient material and pressure to shove material through metal lath and form a good key; 3/8 minimum thickness, score in horizontal direction with metal scorer with clipped teeth to provide good mechanical key for second coat. M. Brown Coat: 1 part Portland Cement, 5 parts sand and hydrated lime equal to 25ʼ% of the volume of cement. N. Finish coat to match adjacent wall surface interior and exterior applications. O. Curing: Keep each base coat moist for at least 48 hours; commence moistening as soon as plaster has hardened sufficiently so to prevent injury; apply water in a fine fog spray; avoid soaking; curing shall proceed over holidays, Saturdays and Sundays if necessary. If atmospheric conditions are hot and dry, curing time shall be extended as necessary. Allow plaster base coats to cure for a minimum of 7 days before applying finish coat. P. Mechanically mix cementitious and aggregate materials for plasters to comply with applicable referenced application standard and with recommendations of plaster manufacturer. 1. Stucco Finish Coat: Factory-packaged stucco, including portland cement, aggregate, coloring agent, and other proprietary ingredients. Add water only; comply with stucco manufacturer's written instructions

5 2. Thickness: 7/8 thick; measured from back of lath or equivalent to original finish thickness. 1.3 EXECUTION A. Lathing: Apply lath with long dimension at right angles to supports; lap sides and ends as recommended by manufacturer. B. Lathing and Furring: Install lath and furring indicated to comply with ML/SFA 920, "Guide Specifications for Metal Lathing and Furring," and with ASTM C C. Install supplementary framing, blocking, and bracing at terminations in work and for support of fixtures, equipment services, heavy trim, grab bars, handrails, furnishings, and similar work to comply with details indicated or, if not otherwise indicated, to comply with applicable written instructions of lath and furring manufacturer. D. Ceiling Suspension Systems: Install ceiling suspension system components of sizes and spacings indicated, but not in smaller sizes or greater spacings than those indicated in ASTM C Coordinate installation of ceiling suspension system with installation of overhead structural systems to ensure inserts and other structural anchorage provisions have been installed to receive ceiling hangers in a manner that will develop their full strength and at spacings required to support ceiling. 1. Hanger Installation: Attach hangers to structure above ceiling to comply with ML/SFA 920, "Guide Specifications for Metal Lathing and Furring," and with referenced standards. E. Installation of Vertical Metal Furring: Install ceiling suspension system components of sizes and spacings indicated, but not in smaller sizes or greater spacings than those required to comply with ML/SFA 920, "Guide Specifications for Metal Lathing and Furring," and with referenced standards. For furring on interior side of exterior walls, provide furring brackets, unless otherwise indicated. F. Preparing Solid Surfaces for Plastering: Clean plaster bases and substrates for direct application of plaster, removing loose material and substances that may impair the Work. 1. Etch concrete and concrete unit masonry surfaces indicated for direct plaster application to obtain adequate suction and mechanical bond of plaster (where dash coat, bonding agent, or additive is not used). 2. Apply bonding agent on concrete and concrete unit masonry surfaces indicated for direct plaster application; comply with manufacturer's written instructions for application. 3. Apply dash coat on concrete surfaces indicated for direct plaster application. Moist-cure dash coat for at least 24 hours after application and before plastering. 4. Install temporary grounds and screeds to ensure accurate rodding of plaster to true surfaces; coordinate with scratch-coat work

6 5. Surface Conditioning: Immediately before plastering, dampen surfaces indicated for direct plaster application, except where a bonding agent has been applied. Moisten to obtain optimum suction for plastering. G. Installation of Plastering Accessories: Comply with referenced lathing and furring installation standards for provision and location of plaster accessories of type indicated. Install accessories of type indicated at following locations: 1. External Corners: Install corner reinforcement at external corners. 2. Terminations of Plaster: Install casing beads, unless otherwise indicated. 3. Control Joints: Install at locations indicated or, if not indicated, at locations complying with the following criteria and approved by Architect / Engineer: a. Where an expansion or contraction joint occurs in surface of construction directly behind plaster membrane. b. Distance between Control Joints: Not to exceed 18 feet in either direction or a length-to-width ratio of 2-1/2 to 1. c. Wall Areas: Not more than 144 sq. ft. d. Horizontal Surfaces: Not more than 100 sq. ft. in area. e. Where plaster panel sizes or dimensions change, extend joints full width or height of plaster membrane. H. Plaster Application: Sequence plaster application with installation and protection of other work so that neither will be damaged by installation of other. Do not use materials that are frozen, caked, lumpy, dirty, or contaminated by foreign materials. Do not use excessive water in mixing and applying plaster materials. 1. Plaster Application Standard: Apply plaster materials, composition, mixes, and finishes indicated to comply with ASTM C Tolerances: Do not deviate more than plus or minus 1/8 inch in 10 feet from a true plane in finished plaster surfaces, as measured by a 10-foot straightedge placed at any location on surface. 3. Grout hollow-metal frames, bases, and similar work occurring in plastered areas, with base-coat plaster material, before lathing where necessary. Except where full grouting is indicated or required for fire-resistance rating, grout at least 6 at each jamb anchor. 4. Plaster flush with metal frames and other built-in metal items or accessories that act as a plaster ground, unless otherwise indicated. Where plaster is not terminated at metal frame by casing beads, cut base coat free from metal frame before plaster sets and groove finish coat at junctures with metal. 5. Corners: Make internal corners and angles square; finish external corners flush with cornerbeads on interior work, square and true with plaster faces on exterior work

7 6. Thickness: As indicated or as required by ASTM C 926. I. Finish Coats: To match adjacent wall surface finish. J. Moist-cure plaster base and finish coats to comply with ASTM C 926, including written instructions for time between coats and curing in "Annex A2 Design Considerations." K. Cutting and Patching: Repair cracks and indented surfaces. Point-up finish plaster surfaces around items that are built into or penetrate plaster surfaces. Repair or replace work to eliminate blisters, buckles, check cracking, dry outs, efflorescence, excessive pinholes, and similar defects. Repair or replace work as necessary to comply with required visual effects. L. Cleaning and Protecting: Remove plaster from other surfaces not to be plastered. When plastering is completed, remove unused materials, containers, equipment, and plaster debris. Protect plaster work from damage or deterioration until Substantial Completion. 1.4 MEASUREMENT A. This Item will be measured by the square foot installed complete and in place. A square foot is further defined as a 12 by 12 area or 144 square inch area. B. Note: It is unknown how much area under of the existing exterior stucco will require to be cut and patched due to the installation of the metal wall flashing so for bidding purposes it will be assumed that 100 sq. ft. of vertical wall surface will require replacement / repair. C. Note: There is one (1) area within the building s interior that will require plaster-work. Located above the south main entry door and in an Alamo shape that has deteriorated from a roof leak. 1.5 PAYMENT A. Lath, Stucco and Plaster and Incidentals: The work performed and materials furnished shall be in accordance with this Item and measured as provided under Measurement will be paid for at the unit price bid for Lath, Stucco and Plaster. This price shall be full compensation for furnishing all materials, anchoring, support members, equipment, labor and incidentals to complete the work as shown on the plans