Specification

ManualsBrandsSHEETROCK ManualsBuilding materials3/8 in. x 4 ft. x 8 ft. Gypsum Drywall

A large size, rigid base for economical application of gypsum veneer plasters

— Special gypsum core and multi-layered laminated face paper to control water absorption, provide maximum plaster bond

and resist sag.

— Economical construction. Large-size panels reduce handling.

— Panels are designed for direct or resilient attachment to wood or steel framing.

— I

MPERIAL

Brand Bases comply with ASTM C588 and have gypsum cores UL-Classiﬁed as non-combustible per ASTM E136.

— Foil-Back I

MPERIAL

Brand Gypsum Base has bright aluminum foil backing which meets HUD requirements for a vapor retarder.

Description I

MPERIAL

Brand Gypsum Base is ideally suited for veneer plaster systems. Available in 1/29 and 5/89 thicknesses, 48 wide by

88 to 148 lengths, the panels are large enough to be installed like drywall panels. The distinctive blue face paper is designed

to provide the qualities desirable for veneer plaster applications, that is, it controls water absorption, provides for a strong

plaster bond and resists plaster slide. The panels provide a rigid base that resists sag. When securely attached, gypsum base

adds lateral stability to the assembly. Also, gypsum base partitions faced with gypsum plaster on both sides have high

resistance to sound transmission. Resilient attachment further improves ratings. These panels are not affected by decay, dry

rot or normal moisture; they will not attract vermin.

MPERIAL

Brand Gypsum Base is designed to be used with the following plaster products: I

MPERIAL

Brand Finish Plaster,

MPERIAL

Brand Finish Plaster—Special White, D

IAMOND

Brand Interior Finish Plaster, Norfolk Special Veneer Plaster,

MPERIAL

Brand Basecoat Plaster, D

IAMOND

Brand Veneer Basecoat Plaster, Custom Veneer Basecoat Plaster and USG

Special Basecoat Plaster.

Foil-back panels are intended for use in exterior walls. The bright aluminum foil backing has a permeability of 0.06

perms, which is substantially below the 1.00 perm limit permissible under HUD requirements for a vapor retarder.

Limitations 1. I

MPERIAL

Brand Gypsum Bases should only be used with veneer plaster products.

2. I

MPERIAL

Brand Gypsum Bases should not be used in areas exposed to excessive moisture for extended periods or as a base

for adhesive application of ceramic tile (S

HEETROCK

Brand Gypsum Panels, Water-Resistant, or D

UROCK

Brand Cement

Board are recommended for this use).

3. Do not apply D

IAMOND

Interior Finish Plaster to I

MPERIAL

Brand Gypsum Base that has faded from exposure to sunlight. Where

fading has occurred, treat surface with either USG

™

Plaster Bonder or a spray-applied solution of USG

™

Accelerator-Alum

Catalyst before application of ﬁnish.

4. Gypsum base surfaces should be isolated with control joints or other means where: (a) Partition or furring abuts a structural

element (except ﬂoor) or dissimilar wall or ceiling; (b) Ceiling abuts a structural element, dissimilar wall or partition, or other

vertical penetration; (c) Construction changes within the plane of the partition or ceiling; (d) Partitions or furring run exceeds

308; (e) Ceiling dimensions exceed 308 without relief, or 508 with relief; (f) Expansion or control joints occur in the base

exterior wall. Ceiling-height door frames may be used as control joints, as may door frames that are less than ceiling height,

if control joints extend to ceiling from both corners.

5. Do not exceed the maximum spacing of framing members shown in the table below.

Maximum spacing of framing members for new construction:

base and ﬁnish assembly framing spacing

(1)

in. mm in. mm

1/2 12.7 I

MPERIAL

Brand Gypsum Base

one layer, 1-coat system 16 406.4

one layer, 2-coat system 16 or 24

(2)

406.4 or 609.6

(2)

two layer, 1 & 2-coat system 24 609.6

5/8 15.9 I

MPERIAL

Brand Gypsum Base

one layer, 1-coat system 16 or 24

(2)

406.4 or 609.6

(2)

one layer, 2-coat system 24

(2)

609.6

(2)

two layer, 1 & 2-coat system 24 609.6

(1) For perpendicular or parallel application to framing. Perpendicular is preferred for maximum strength; parallel application is not recommended for

ceilings.

(2) 249 (609.6 mm) spacing requires joint treatment with S

HEETROCK

Brand Joint Tape and S

HEETROCK

® Brand Setting-Type Joint Compound

URABOND

or E

ASY

AND

™

Submittal Sheet

09210

IMPERIAL

Gypsum Base

(Regular Core and Foil Back)

Gypsum Base

Tapered Edge

Summary of content (4 pages)

PAGE 1
® Submittal Sheet 09210 ® IMPERIAL Gypsum Base (Regular Core and Foil Back) A large size, rigid base for economical application of gypsum veneer plasters — Special gypsum core and multi-layered laminated face paper to control water absorption, provide maximum plaster bond and resist sag. — Economical construction. Large-size panels reduce handling. — Panels are designed for direct or resilient attachment to wood or steel framing.
PAGE 2
Directions Installation Preparation Protect the product from moisture during storage and on the job. In cold weather, heat the interior of the building to a minimum of 55 °F (13 °C) for an adequate period before the application of plaster, while basecoat and finish is being applied, and until the finish is dry. Air circulation should be kept at a minimum level during this period. Warning: Store all IMPERIAL Brand Gypsum Base flat. Panels are heavy and can fall over, causing serious injury or death.
PAGE 3
Product Data Materials: Panels with gypsum core, paper encased, square or taped edges. Compliance with Standards: IMPERIAL Brand Gypsum Base meets ASTM Designation C588. Thermal coefficient of expansion (unrestrained): 9.2x10–6 in./in. x °F (40-100 °F); 16.2 mm/km x °C (4-38 °C). Thermal resistance value: R = 0.45 (1/29 base), 0.56 (5/89 base). Hygrometric coefficient of expansion (unrestrained): 7.2x10–6 in./in. x °F (7.2 mm/km x °C) at 5-90% R.H. Vapor Permeance: Vapor Permeance is 0.
PAGE 4
United States Gypsum Company Trademarks The following trademarks used herein are owned by United States Gypsum Company: DIAMOND, DURABOND, DUROCK, EASY SAND, IMPERIAL, SHEETROCK and USG. Note Products described here may not be available in all geographic markets. Consult your U.S. Gypsum Company sales office or representative for information. 125 South Franklin Street P.O. Box 806278 Chicago, IL 60680-4124 A Subsidiary of USG Corporation (800) USG-4YOU (874-4968) http://www.usg.