USG Manufactured Housing Handbook User Manual

Page 8

its blade should be kept sharp so
that the score will be made through
the paper and into the gypsum core
without tearing or rolling up the
paper.

HEETROCK

Brand Gypsum Panels

should not be exposed to exces-
sive or continuous moisture or
extreme temperature (maximum
continuous temperature less than
125 °F). Specially formulated
S

HEETROCK

Brand Panels, Water-

Resistant, are recommended for
areas periodically exposed to high
moisture. For areas subject to
direct or continuous exposure to
moisture, and as a base for

ceramic tile, D

UROCK

௡ Brand Cement

Board is recommended.

7 Ceilings

Ensure that the ceiling assembly
fixture is clean, flat, and square.
Lay out the gypsum panels in
accordance with the design of the
home. Take precautions to avoid
damaging the face, edges, and
ends of the gypsum panel during
layout.

The Gypsum Industry generally
recommends perpendicular
installation for ceiling board.
However, at the discretion of the
home manufacturer, ceiling board

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may be installed parallel if ade-
quate measures are taken to pre-
vent board sag. Board sag is
caused by exposure to moisture
from finishing products, high
ambient humidity, and insulation
loading on the back of the board.
Humidity/moisture control
requires adequate ventilation in
the plant to remove moisture
introduced during finishing.
Supplemental heat and dehumid-
ifiers may be required to remove
moisture.

Assemble the roof structure over
the gypsum panels and attach the
gypsum panels to the framing
using the specified mechanical or
adhesive fastening schedule.

Do not extend the gypsum ceiling
board between the roof end rail
and the perimeter bearing walls.
Use a wood compression strip to
carry the load.

8 Walls

Apply panels horizontally or verti-
cally to framing so as to minimize
the amount of joint work required.

a For gypsum board attached on

the assembly table, take pre-
cautions to avoid wiping adhe-
sive off the framing as panels
are slid into place. Do not allow
the gypsum board to extend
beyond the plates or wall ends.

b For boards installed with the

walls in the unit (back panel-
ing)—if applied horizontally,
install top row first. Position
first panel tight against the
installed ceiling panel and fas-
ten to studs. Space nails or sta-
ples maximum 8

Љ apart along

framing, screws 16

Љ apart,

starting at the restrained edge
or end of the panel and working
outward toward the free end.
Cut panels accurately so that
they do not have to be forced
into place.

Apply lower row of panels so
that tapered edges meet with
those of top row. Vertical joints
should be staggered. Avoid ver-
tical joints directly above or
below the corner of a window,
door, or other opening for best
decorating results.

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Maximum Support (Studs, Joists, Channels, Furring) Spacing
for Gypsum Panels:

Max. Support

Panel

Spacing o.c. (in.)

Thickness

(1)

Location

Application Method

(2)

in.

Single-layer application—T

-B

ASE

or Regular Gypsum Panels

3/8

ceilings

(3)

perpendicular

(4)

406

(9.5 mm)

sidewalls

parallel or perpendicular

406

1/2

ceilings

parallel

406

(12.7 mm)

perpendicular

(5)(6)

610

sidewalls

parallel or perpendicular

610

5/8

ceilings

(6)

parallel

406

(15.9 mm)

perpendicular

610

sidewalls

parallel or perpendicular

610

Single-layer application—1/2

Љ S

HEETROCK

MH Brand Gypsum

Ceiling Board, U

LTRA

-B

ASE

1/2

ceilings

(

parallel or perpendicular

610

(12.7 mm)

sidewalls

parallel or perpendicular

610

(1) A 5/8

Љ thickness is recommended for the finest single-layer construction, providing increased resistance to fire and

transmission of sound; 1/2

Љ is standard for single-layer application in new residential construction. (2) Long-edge

position relative to framing. (3) Not recommended below unheated spaces. (4) Not recommended if water-based tex-
turing material is to be applied. (5) Max. spacing 16

Љ if water-based texturing material to be applied. (6) If 1/2Љ

HEETROCK

MH Brand Gypsum Ceiling Board (U

LTRA

-B

ASE

) is used, max. spacing is 24

Љ o.c. for parallel application with

weight of unsupported insulation not exceeding 2.2 psf. When water-based texturing materials are used, environmen-
tal controls must be in place to adequately dry interior finishes and reduce high ambient humidity.
Application method: “Parallel” and “perpendicular” refer to the position of the paper-wrapped edge of the gypsum
panel.
Limitations on 3/8

Љ panels: 3/8Љ gypsum panels shall not be used for ceilings below unheated spaces or as a sub-

strate for water-based finishes.
Limitations on regular 1/2

Љ panels: 1/2Љ gypsum panels shall not be used in ceiling applications when truss spac-

ing exceeds 16 in. o.c. and water-based finishes are applied.
U

LTRA

-B

ASE

Ceiling Board: 1/2

Љ S

HEETROCK

MH Brand Gypsum Ceiling Board (U

LTRA

-B

ASE

) is recommended for ceiling

applications when water-based finishes are specified.

CAUTION: Continuous film poly-vapor barriers used in conjunction with wet-textur-
ing will increase the tendency of the board to sag.Alternative vapor barriers should
be used when texturing is specified.