M-Bloc Wallboard FAQs
American Gypsum provides answers to the most commonly asked questions about our paper faced mold & moisture resistant M-Bloc Wallboard Panels.
Fire and Sound Ratings
Fire and Sound Ratings are established at certified laboratories to the requirements of ASTM E119 or UL U263 for fire endurance and ASTM E90 for sound rated systems. The designs found on the following pages or at www.americangypsum.com/resources/design-library are summaries only, and building owners, design professionals, builders and contractors are strongly encouraged to review the listing or test report to ensure that each component of the design is being used and assembled properly on their projects. For details of a specific test, call 1-800-545-6302 ext. 5607.
Supplementary Information about Fire and Sound Ratings
- Indicated stud, truss or joist spacings are maximums.
Greater stud, truss or joist sizes/depths shall be permitted to be used in wood or metal systems.
- Metal studs and runners of a thicker/heavier mil thickness than those specified in a design are permitted.
- The use of the thicker/heavier mil framing member, or the reduction of spacing of such framing member may reduce the STC or IIC sound rating of a system.
- The use of sound isolation clips to separate a gypsum panel from its framing member, will improve the sound dampening performance of the assembly.
- The assigned rating of any load-bearing system shall also apply to the same system when used as a non-load-bearing system.
- 5/8" FireBloc® Type C may be substituted for 5/8" FireBloc® Type X, but FireBloc® Type C must be used in designs specifying that product.
- Fasteners shown in designs are minimums length, head diameter, etc. Screws may be substituted for a specified nail, when the length and head diameter are equal or exceed those of the nails, and then spaced not to exceed those described for the identified nail. Nails shall meet the requirements of ASTM F547 or ASTM C514, and screws are to adhere to ASTM C1002.
- Unless noted in the design, the face layer of an assembly (except those with pre-decorated surfaces or exterior gypsum sheathing) shall have joints taped and fastener heads treated (minimum Level 1 as found in GA-214 - Recommended Levels of Finish for Gypsum Board, Glass Mat and Fiber-Reinforced Gypsum Panels). Additionally, the base layers in multi-layer assemblies are not required to have joints or fasteners treated with tape and joint compound.
- For the use of insulation (glass, mineral fiber or blown-in) in floor/ceiling and roof/ceiling assemblies, the user shall identify the designs requirements. For fire rated assemblies with no mention of insulation, the user may add such – when an additional layer of gypsum wallboard of the same type specified in the design is added to the ceiling.
Wood structural panels (OSB, plywood) may be added to a fire rated wall system. A minimum 7/16" OSB or 15/32" plywood complying with DOC PS1 or PS2, or APA Standard PRP-108, may be installed horizontally or vertically and applied as a base layer, in between wallboard layers, or as the face or final layer to complete a system. When wood structural panels are added, the length of the fastener must be increased to compensate for the additional thickness.
In each UL fire rated design, approved wallboard panels are listed by their "UL Type" designations. Below are American Gypsum's "UL Types" and our wallboard panel or panels that correlate to each.
||5/8" FireBloc® Type X Gypsum Wallboard
5/8" Exterior Sheathing
5/8" Exterior Soffit Gypsum Wallboard
5/8" M-Bloc® Type X with Mold & Moisture Resistance
5/8" M-Bloc® AR Type X Abuse with Mold & Moisture Resistance
5/8" M-Bloc® IR Type X Impact with Mold & Moisture Resistance
||1/2" FireBloc® Type C Gypsum Wallboard
5/8" FireBloc® Type C Gypsum wallboard
5/8" FireBloc® Type C Soffit Gypsum Wallboard
5/8" M-Bloc® Type C with Mold & Moisture Resistance
||5/8" LightRoc® Type X Gypsum Wallboard
||1" M-Bloc® Shaft Liner
||5/8" M-Glass® Exterior Gypsum Sheathing with Mold & Moisture Resistance
1" M-Glass® Shaft Liner with Mold & Moisture Resistance