Updated: Aug 29, 2019
Handling/Storage: Although GFRG is strong, it is a gypsum product that is subject to damage when improperly stored or handled. Pieces should be stored upright, in a controlled, weather protected environment, and on a level surface similar to conditions that are required for drywall. It is important not to lea GFRG at angle, lay flat, or stack parts on top of each other. Parts that are improperly stored may become warped. Imperfections in the shape can usually be corrected by wetting out the back of the pieces and installing before drying.
Cutting/Drilling: Blades and drills designed for metal produce good results. Slow, steady cuts reduces chipping and the number of teeth on the blade determines the quality of the cut. Pre-drill and countersink all fastener heads. Wear a mask to minimize inhalation of gypsum dust produced by the cutting and drilling of GFRG products.
Assembly/Installation: Before starting, one should review show drawings and familiarize themselves with the dimensions of the product. The dimensions of the product should be confirmed to match the shop drawings. Large profiles (ceiling panels, etc…) will be somewhat flexible which will allow for some adjustments, but also provide some difficulty in measuring. If necessary, use clamps or other methods to correct shape. Any discrepancies or confusion must be brought to the manufacturer’s attention before installing the product. Basic methods and criteria are the same as those required to install drywall. Due to GFRG’s many different shapes/applications, specific installation instructions are most appropriately developed from the shop drawings of the parts supplied. The following information is a general guide for GFRG products that may or may not apply to your specific product. Structural framing and attachment spacing is subject to applicable local code and may supersede those shown in the shop drawings. Control and expansion joint locations are the same as required for drywall.
Metal Framing/Supports: Minimum 20 gauge studs, angles, 12 gauge hanger wires, threaded rods, clips, etc., plumbled/aligned with inside or back of attachment flanges and securely anchored to adjacent structures. Additional supports not shown in shop drawings may be required.
Fasteners: As required for framing being used, but typically standard drywall screws of lengths as required. Pre-drill and countersink into the surface at thickened flange locations, inside tape/bed recesses if provided for field finishing to a “seamless” appearance. Do not “overdrive” but instead, shim out from framing to the back of GFRG flanges. GFRG will flex somewhat to allow minor adjustment. For “returned” flanges it is possible to “toe screw” across seams to secure parts until adhesive set or if necessary for alignment.
Adhesive: Good quality, construction adhesive suitable for plaster/drywall applications. Apply liberally at piece to piece connections and/or adjacent construction. Liquid nails, PL400, PL-Premium, etc. or equal.
Fiberglass Mesh Tape: 2” wide, suitable for plaster applications. Paper tape is not recommended.
Patching/Joint Finishing/Painting: Clean the GFRG surface to remove any dust, oils, etc. with a non-oil based solvent such as acetone or isopropyl alcohol and/or plain water without soap. GFRG is hydroscopic meaning it will tend to pull water from the joint compound as it is being spread across the surface. Pre-moisten the surface to be patched and/or filled prior to applying the compound with a damp sponge and allow excess to be absorbed. Embed standard 2” mesh into the seam recess with joint compound. Multiple coats are required as with drywall, “floating” away from the seams to create a monolithic surface. Sand patches and compounds with 120 grit production paper, back to the original profile, following the curvature of the piece if applicable. Take care to prevent “crowning” of pacth at seams as this will read through after priming. Proper priming of GFRG and joint compound surfaces is extremely important to minimize the differences in porosity between the two materials and eliminate the chances of seam “read through”. Use both a good quality primer and final coating designed specifically for interior drywall and/or plaster. Two primer coats, rolled on, may be needed. Re-sand surfaces between coats as needed. Finish quality levels and the methods to achieve them are also as required for drywall per the references listed above, especially for critical lighting applications and for coatings with any gloss appearance. High-gloss paints are specifically not recommended. These will almost surely exhibit seam “read through” even if properly specified and all parties are aware of the extra field measures necessary for their use. GFRG is not inherently perfect, smooth, non-textured finishes may require additional floating, primer coats, and sanding to obtain an acceptable finish. In some cases an applied skim coat may be necessary for the entire surface. Consult the manufacturer for further instructions in these situations.