National Gypsum Construction Guide

Wood Frame Walls and Ceilings/Double Layer Construction
DESCRIPTION
09 29 00/NGC
BUYLINE 1100
INSTALLATION
The Gold Bond double layer
system consists of a face
layer of gypsum board joblaminated
to a base layer of
gypsum wallboard, or
gypsum sound deadening
board applied with power
driven screws or staples, or
nailed to the framing in the
conventional manner.
DETAILS
CEILING DETAIL
STUD
PLATE
JOIST
RECOMMENDATIONS
DOUBLE LAYER
WALLBOARD
1. Base layer
The first layer may be
specified the same as single
layer application except
that fasteners shall be
driven flush with the board
surface and joints will not
be treated. Base layer must
not be secured to framing
with clips.
2. Adhesive Application of
Face Layer, General
a. All joints shall fall at least
10" from parallel joints in
the base layer. Adhesive
shall be: (select one)
b. ProForm all-purpose ready
mix joint compound or
Sta-Smooth setting type
compound applied with a
notched spreader to the
back side of the finish
layer.
c. Adhesive is applied with a
caulking gun. Align board
edges. Reference ASTM
C 840, section 9.
OUTSIDE CORNER
PLATE
CORNERBEAD
PLATE
INSIDE CORNER
3. Adhesive Application,
Regular Gypsum Board
The finish layer shall be
positioned on the wall or
ceiling within 10 minutes
(unless otherwise specified
above) and held in place
with sufficient temporary
(nails) (Type G Drywall
Screws) (bracing) to ensure
adequate contact and
alignment of the gypsum
boards. When the bond
has developed (usually
24 hours) the temporary
(fasteners) (bracing) shall be
removed. Resulting holes
shall be filled flush to the
surface with Joint
Compound and the joints
shall be finished.
Cornerbead shall be
applied at all exterior
angles.
4. Adhesive Application,
Prefinished Gypsum Board
a. Pre-bow board by storing
overnight in such a position
that the ends of each board
curve away from the base
layer when put in vertical
mounting position.
b. Apply ready-mix or Sta-
Smooth joint compound in
nominal 5" ribbons of four
1/4" x 1/4" beads located
around the perimeter and
center of the boards
(approximate coverage for
ready-mix is 9-10 gal./1000
sq.ft and Sta-Smooth is 50-
60 lbs./1000 sq.ft.). An
alternative is 2" diameter
daubs 1 /2" thick, 16" o.c.
(approximate coverage for
ready-mix is 5 1/2"-6
gal./1000 sq.ft. and Sta-
Smooth is 30 - 35 lbs./1000
sq.ft.).
c. Temporarily brace, as
required, to ensure proper
contact and edge alignment
of boards.
5. Mechanical Application of
Face Layer
Mechanical attachment of
face layer for fire or sound
rated constructions shall be
made in accordance with
the specifications for the
system selected.
For non-rated construction,
nails used in wood framing
to supplement adhesive
shall be type GWB, of a
length to provide 7/8"
minimum penetration into
framing and shall be
spaced 16" o.c. max.
Screws used in wood
framing shall be Type W, of
a length to provide
minimum 5/8" penetration
into the framing and shall
be spaced 24" o.c. max.
If no adhesive is used,
standard fastener spacings
shall prevail.
SPECIFICATIONS
See CSI 3-Part format
Generic/Proprietary
Specifications on
page 118.
In double layer construction
use any of the following
appropriate laminating
adhesives: (1) Sta-Smooth
Compound or Sta-Smooth
Lite for fast hardening;
(2) All-Purpose Joint
Compound for spreading
on the back surface of the
finish layer boards: (3)
drywall adhesive meeting
ASTM C 557.
Base layer is applied on
ceilings, then sidewalls,
secured with 1 1/4" Type
W Screws 12" o.c. on
ceilings, 16" o.c. on walls;
nails located 7" o.c. on
ceilings; 8" o.c. on
sidewalls; staples 5" o.c. on
ceilings and 6" o.c. on
sidewalls.
Finish layer is temporarily
nailed or braced until
adhesive dries. On walls,
prefinished boards, applied
vertically, can be prebowed,
nailed just top and
bottom.
RECOMMENDATIONS
1. Double layer wallboard
application over wood
framing is recommended
for the ultimate in wall
surfacing and in areas
where increased fire
protection and better sound
insulation are desired
between rooms. (For test
results see pages 13-14 of
this guide.) Custom built
homes, commercial
buildings and party walls
between apartments would
be considered appropriate
areas for double layer
application.
09 29 00
NATIONAL GYPSUM WALLBOARD PRODUCTS
101