Specifying laminated core noise-reducing gypsum board and insulation
The first step in writing specifications for laminated core noise-reducing gypsum board, including noise-reducing fibreglass insulation in the cavity, is calculating the sound rating needed for the building’s wall assemblies and designing them accordingly.
In this process, the following options should be considered:
- thicknesses of 13 or 16 mm (1/2 or 5/8 in.) Type X;
- widths of 1.2 m (4 ft);
- lengths of 2.4 m (8 ft) or custom;
- tapered edges; and
- compliance with ASTM C1396, Standard Specification for Gypsum Board, and ASTM C1629, Standard Classification for Abuse-resistant Nondecorated Interior Gypsum Panel Products and Fiber-reinforced Cement Panels
The second step is to compare the laminated core noise-reducing gypsum board systems against other contemporary gypsum board systems. Online calculator tools have been developed for this very purpose. By inputting site-specific material and installation costs and collaborating with manufacturers’ field sales representatives, design professionals can determine a customized comparison of the cost per area for the wall assemblies.
The final step is to calculate the extra real estate rewards from thinner laminated gypsum walls. Again, a calculator tool can be used for this purpose. For example, using the most recent Toronto average condo price of $382,070 and a 93-m2 (1000-sf) condo area, it is estimated an extra profit of $1800 and $1500 (for a total of $3200) are possible by using laminated core noise-reducing gypsum versus double layer 15.9-mm (5/8-in.) Type X and 12.5-mm (½-in.) resilient channels respectively. Financial savings will vary depending on the market where the analysis is based.
Installers may follow traditional interior gypsum board application and finishing methods when working with laminated noise-reducing gypsum board, but with a little more attention to detail for better acoustic performance. For instance, the board layout should stagger joints from one side of the wall to the other. Next, sound-absorbent fibreglass batt insulation should be installed in wall cavities for higher STC ratings where needed. Again, resilient channels in this application are no longer needed to achieve performance except in very acoustically sensitive situations. However, it is appropriate to specify putty pads—tested per ASTM E90, Standard Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and Elements—or acoustical sealant to seal off sound flanking paths, such as electrical outlets and switch cutouts.
Panels of noise-reducing gypsum board should be installed per Gypsum Association (GA)-216/ASTM C840, Application and Finishing of Gypsum Panels and the manufacturers’ application instructions. Best practices call for a 6-mm (1/4-in.) gap around all wall perimeter edges to allow for any movement. Installers can cut laminated noise-reducing gypsum boards as they would other gypsum board—by deeply scoring from both sides and snapping. However, cutting across a 1.2 m (4 ft) width may require use of a hand or power saw. An acoustical sealant should be specified to seal the perimeter gaps and wall penetrations per ASTM C919, Standard Practice for Use of Sealants in Acoustical Application.
Laminated core noise-reducing gypsum board may be finished, painted, or wallpapered using conventional techniques. GA-214, Recommended Levels of Gypsum Board Finish, should be referenced when specifying the level of finishing desired.
