Installation Guide

21
DECKING
20
DECKING
GAPPING
You must gap Trex
®
decking, both end-to-end and
width-to-width. Gapping is necessary for drainage and
the slight thermal expansion and contraction of Trex
decking boards. Gapping also allows for the shrinkage
of the wood joist system.
» ALWAYS follow Trex-recommended gapping
gu
idelines.
»
M
aximum allowable perpendicular overhang for Trex
is 4" (10.2 cm).
» All decks require air circulation to keep them dry
a
nd looking good. To improve air flow, leave
openings under the decking or increase gapping to
3
/8" (1 cm).
End-to-End/End-to-Width
Gap Trex decking end-to-end, based upon the
temperature at installation. See chart at left. For
fastening tips, see page 17.
Abutting Solid Objects
When decking is abutting a wall, you must also gap it
1/4" - 1/2" (0.6 - 1.3 cm) depending on the temperature
at installation. See chart at left.
Width-to-Width
The minimum required width-to-width gapping is
1 /4" (0.6 cm). When installing in temperatures below
40°F (4.5°C), Trex recommends 3/8" (1 cm) gapping.
For docks and heavily wooded areas, Trex recommends
a 3/8" (1 cm) gap as well. No gapping should ever
exceed 1/2" (1.3 cm).
1/4" – 3/8"
(0.6 cm – 1 cm)
*Temperature at installation.
*Temperature at installation.
END-TO-END/END-TO-WIDTH AND ABUTTING GAP
End-to-End/
End-to-Width
Abutting Gap
Above 40°F* (4.5°C)* 1/4" (0.6 cm)
Below 40°F* (4.5°C)* 3/8" (1 cm)
WIDTH-TO-WIDTH GAP
» When you use the recommended hidden fasteners,
t
he placement of the hidden fastener establishes the
designated gap size.
» When installing fascia, gapping rules must apply.
1/8" – 3/16"
(0.3 cm – 0.5 cm)
1/4" – 1/2"
(0.6 cm – 1.3 cm)
Above 40˚ F* (4.5 C)* 1/8" (0.3 cm) 1/4" (0.6 cm)
Below 40˚ F* (4.5 C)* 3/16" (0.5 cm) 1/2" (1.3 cm)
STAIRS
Stairway Detail
» Stair treads built with Trex
®
meet requirements by
t
he major national building codes. Consult your local
municipality for specific requirements.
» Fasten stair treads continuously across at least four
s
tringers.
»
S
ee chart (at right) for center-to-center spacing of
profiles.
» Dress the sides of the stringers and risers with Trex
f
ascia or trim for a finished look.
»
M
ost model building codes require the stair treads
to be constructed under the following requirements:
› Stairways must be at least 36" (91.5 cm) wide
› Stair treads must be at least 11" (28 cm) deep*
» Gapping between Trex boards on stair treads must
b
e 1/4" - 3/8" (0.6 cm - 1 cm).
»
T
he overhang of the stair tread is not to exceed
1/2" (1.3 cm).
* 5" (12.7 cm) wide Contours® will require gapping at the riser to
meet the 10" tread requirement with 3/4" – 1-1/4" (2 cm - 3.2 cm)
nosing.
NOTE: Trex rails meet all major building codes for use
as a guardrail system. Local municipalities may require
a graspable handrail on stairways. Check with your local
building code official for local requirements. See Trex
ADA Handrail System on pages 72 - 75.
5” Wide Contours Stairs
Option 1: Using two deck boards.
a
.
3
/8" (1 cm) gap at riser and between each board.
Op
tion 2: Using two deck boards.
a. 1/2" (1.3 cm) gap at riser and 1/4" (0.6 cm) gap
b
etween each board.
Op
tion 3: Using a feature board—a ripped piece of
Contours 1-1/8" (3 cm) from the edge.
a
.
F
eature board should be installed with factory
end side facing up.
b
.
T
here should be no gap at the riser.
c. Install as follows:
» R
iser, full board, 1/4" (0.6 cm) gap, featur
e
board, 1/4" (0.6 cm) gap, full board.
» R
iser, feature board, 1/4" (0.6 cm) gap, full
board, 1/4" (0.6 cm) gap, full board.
MAXIMUM SPACING ON CENTER OF JOIST
2" x 6" (5.1 x 15.2 cm), 1" (2.5 cm) Boards 12" (30.5 cm)
Brasilia, 5" Contours, and Escapes 9" (24 cm)
Riser trim removed
for clarity
12" (30.5 cm) max
for 2" x 6" (5.1 cm x 15.2 cm)
and 1" x 6" (2.5 x 15.2),
9" (24 cm) for Brasilia, Contours
and Escapes
36" (91.5 cm)
min. width –
4 stringers
required
Stair Tread
1" x 8"
(2.5 cm x 20.3 cm)
Riser
11" (27.9 cm)
min. depth
Stringer
NOTE: 4 stringers
are required if 12"
(30.5 cm) span; 5
stringers are required
if 9" (22.9 cm) span.