Your questions answered


Questions most frequently asked by callers to National Gypsum Construction Services

800 NATIONAL Construction Services

What is the difference between 5/8” Type X and 5/8” Type C gypsum board?

Both Gold Bond® Fire-Shield® Gypsum Board and Gold Bond® Fire-Shield C™ Gypsum Board meet the definition of Type X as defined by ASTM C1396. There is no definition for “Type C” in ASTM C1396. Fire-Shield C is simply a more fire-resistant Type X gypsum board for fire-rated assemblies that are more difficult to pass. Typically, these are horizontal assemblies such as roof-ceiling or floor-ceiling assemblies.

Are steel studs better than wood studs to use for acoustical wall assemblies?

Yes, light gauge steel studs provide the best STC acoustical performance. Wood studs are more rigid and transfer more sound.

Does stud spacing affect the performance of an acoustical wall assembly?

Yes, maximum 24” on center stud spacing provides the best STC results. Decreasing the stud spacing to 16” on center will stiffen the wall decreasing the STC results.

I don’t see my assembly. Is there a way to calculate the STC?

No, there is no material additive method for calculating the STC of an assembly. Estimates can be made based on similar systems.

What gypsum board product can I use in an indoor swimming pool area?

Gypsum board is not permitted in swimming pool areas. Use PermaBASE® Cement Board or Gold Bond® eXP® Tile Backer with a direct-applied pool enclosure coating.

What is the proper screw pattern for the application of gypsum board to walls and ceilings?

  • Space screws 12” o.c. max. for walls framed 24” o.c.
  • Space screws 16” max. for walls framed 16” o.c.
  • Space screws 12” o.c. max. for ceiling applications.

Can I use 1/4” PermaBASE® Cement Board on walls?

No, 1/4” cement board products should only be installed over wood floors or counter tops with a continuous substrate.

What products can I use for an exterior soffit?

Use Gold Bond® XP® gypsum board products or Gold Bond® eXP® glass mat gypsum panel products for protected exterior soffits. eXP products will require a skim coat of setting-type joint compound prior to painting. Finish joints and spot fastener with setting-type joint compound.

What is the difference between ready mix and setting type joint compound?

Ready mix compounds are ready-to-use out of the pail and harden by drying. Additional coats can be applied after the prior coat is dry, usually in about 24 hours. Setting type compounds come in powder form and are mixed with water. They harden by way of a chemical reaction known as setting and are available in various set times from 5 to 210 minutes. Once set, additional coats can be applied.

What gypsum board products are permitted to be installed prior to building dry-in (pre-rock)?

Paper-faced products are not permitted to be installed before weather protection is provided. Use Gold Bond® eXP® Interior Extreme® glass-mat faced gypsum panel products before the building is enclosed.

What is the difference between Hi-Abuse and Hi-Impact gypsum board?

Gold Bond® XP® Hi-Abuse® Gypsum Board is manufactured for use in areas where surface abrasion, indentation and mold/moisture resistance is a concern. Gold Bond® XP® Hi-Impact® Gypsum Board has all the attributes of Hi-Abuse board, plus an additional layer of fiberglass mesh embed into the core, providing impact penetration resistance.