1、 Recommended Levels of Gypsum Board Finish GA214M97 Introduction In 1988, as a means of resolving a common problem, four major trade associations concerned with the manufacture, erection, finish, and deco-ration of gypsum board wall and ceiling systems developed an industry-wide, Recommended Levels
2、of Gypsum Board Finish. The document was intended to assist specification writers, architects, contractors, and building owners to more precisely describe the finish of walls and ceil- ings prior to the application of paints and other finishes, to encourage competitive bidding of suitably finished s
3、urfaces, and to enhance the ap-pearance of the final decorative treatment and thereby enlist a satisfied client. The original document was updated and revised in 1996. This document takes the section of the 1996 document that discusses the specific criteria required to achieve individual levels of f
4、inish and presents them in a non-text format. The information contained in the document is technically identical to the original; however, it is formatted, solely for ap-pearance purposes, into a matrix or grid simply to improve its readabili- ty. The scope, terminology, comments and resources secti
5、ons are repro-duced in their entirety from the original document. Scope. This document describes various levels of finish of gypsum board surfaces prior to the application of specific types of final decoration. The recommended level of finish of gypsum board wall and ceiling surfaces varies with the
6、 final decoration to be applied and can also be dependent on their location in a structure and the type of illumination striking the sur-face. Each recommended level of finish is described with typical applica-tions. Terminology. The following definitions are applicable to this document. Accessories
7、: Metal or plastic beads, trim, or moulding used to protect or conceal corners, edges, or abutments of the gypsum board construction. Critical Lighting: Strong sidelighting from windows or surface-mounted light fixtures. syn severe lighting. See “comments“ section of this document. Joint Photographi
8、ng: The shadowing of the finished joint areas through the surface decoration. syn telegraphing. Drywall Primer: A paint material specifically formulated to fill the pores and equalize the suction difference between gypsum board surface paper and the compound used on finished joints, angles, fastener
9、 heads, and accessories and over skim coatings. See “comments“ section of this document. Skim Coat: A thin coat of joint compound, or a material manufactured especially for this purpose, applied over the entire surface to fill imperfec-tions in the joint work, smooth the paper texture, and provide a
10、 uniform surface for decorating. Excess compound is immediately sheared off, leaving a film of skim coating compound completely covering the paper. Spotting: To cover fastener heads with joint compound. Texture: A decorative treatment of gypsum board surfaces. Texturing: Regular or irregular pattern
11、s typically produced by applying a mixture of joint compound and water, or proprietary texture materials including latex base texture paint, to a gypsum board surface previously coated with drywall primer. See “comments“ section of this document. Comments. Critical (Severe) Lighting Areas. Wall and
12、ceiling areas abutting window mullions or skylights, long hallways, or atriums with large surface areas flooded with artificial and/or natural lighting are a few examples of critical lighting areas. Strong sidelighting from windows or surface-mounted light fixtures may reveal even minor surface impe
13、r-fections. Light striking the surface obliquely, at a very slight angle, greatly exaggerates surface irregularities. If critical lighting cannot be avoided, the effects can be minimized by skim coating the gypsum board surface, by decorating the surface with medium to heavy textures, or by the use
14、of draperies and blinds which soften shadows. In general: gloss, semi-gloss, and enamel finishes highlight surface defects; textures hide minor imperfections. Manufacturer Recommendations. The recommendations of individual manufacturers of gypsum board, joint tapes and compounds, acces-sories, drywa
15、ll primers, wallcoverings, adhesives, texture materials, and paints may vary from what is recommended herein and as such are not a part of this recommended specification. Drywall Primer. Applied as a first coat to the entire prepared gypsum board surface with brush, roller, or spray prior to decorat
16、ion. Where final appearance is critical, the application of high quality, high solids, drywall primer will minimize most decorating problems. For finish paints: A good quality, white, latex drywall primer formulated with higher binder solids, applied undiluted, is typically specified for new gypsum
17、board surfaces prior to the application of texture materials and gloss, semi-gloss, and flat latex wall paints. An alkali and moisture-resistant primer and a tinted enamel undercoat may be required under enamel paints. Consult with the finish paint man-ufacturer for specific recommendations. For wal
18、lcoverings: White, self-sizing, water base, “universal“ (all-pur-pose) wallcovering primers have recently been introduced into the mar-ketplace for use on new gypsum board surfaces. These products are claimed to minimize damage if wallcoverings are subsequently removed, bind poor latex paint, allow
19、hanging over glossy surfaces and existing vinyls, hide wall colors, and to be water washable. Texturing. Texture material is applied by brush, roller, spray, or trowel, or a combination of these tools, depending on the desired result. Tex-tured wall surfaces are normally overpainted with the desired
20、 finish; overpainting of textured ceiling surfaces may not be deemed necessary where an adequate amount of material is applied to provide sufficient hiding properties. A drywall primer may not be required under certain proprietary texture materials; consult with the manufacturer of the tex- ture mat
21、erials for specific recommendations. Tool Marks and Ridges. A smooth surface may be achieved by lightly sanding or wiping joint compound with a dampened sponge. Care shall be exercised to ensure that the nap of the gypsum board facing paper is not raised during sanding operations. For additional inf
22、ormation on the finishing of gypsum board surfaces consult ASTM Standard C 840. Resources: Designers and specifiers are encouraged to consult the fol-lowing reference documents: ASTM C 840, Standard Specification for Application and Finishing of Gypsum Board. American Society far Testing and Materia
23、ls, West Con-shohocken, PA. GA-216, Specifications for the Application and Finishing of Gypsum Board, 1996. Gypsum Association, Washington, D.C. GA-505, Gypsum Board Terminology, 1991. Gypsum Association, Washington, D.C. Master Painters Glossary, Painting and Decorating Contractors of America, Fair
24、fax, VA. Contact one of the following associations for additional assistance or copies of this recommended specification: The Association of the Wall and Ceiling IndustriesInternational 803 West Broad Street, Suite 600 Falls Church, Virginia 22046 Telephone: (703) 534-8300 http:/www.awci.org Ceiling
25、s & Interior Systems Construction Association 1500 Lincoln Highway, Suite 202 St. Charles, Illinois 60174 Telephone: (630) 584-1919 http:/www.cisca.org Gypsum Association 810 First Street NE, #510 Washington, DC 20002 Telephone: (202) 289-5440 Painting and Decorating Contractors of America 3913 Old
26、Lee Highway, Suite 33B Fairfax, Virginia 22030 Telephone: (703) 359-0826 http:/ Notice All of the statements, opinions, specifications, and recommendations on levels of gypsum board finish contained in this publication are for general information purposes only and are not intended to imply that thes
27、e are the only materials, procedures, process- es, or methods which are available or suitable. By publishing this document, the co-sponsoring trade associations, and their member com-panies, individually or collectively, make no express or implied warranty or other repre-sentation as to the quality, characteristics, or suitability of the materials or techniques de-scribed herein, and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose which may arise by operation of law or otherwise. Matrix Edition:
