Installation Guide

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DECKING

ROOFTOP AND SLEEPER DECK SYSTEMS

NOTE: Construction methods are always improving. Please refer to www.trex.com for the most up-to-date installation requirements.

» It is recommended that building code approved

structural material be used as the supports.

» Gapping rules are required when installing Trex

decking:

TYPE OF GAP

Above 40°F

(4.5°C)

Below 40°F

(4.5°C)

Width-to-Width 1/4" (6 mm) 3/8" (10 mm)

End-to-End 1/8" (3 mm) 3/16" (5 mm)

End-to-Width 1/8" (3 mm) 3/16" (5 mm)

Abutting Solid Objects 1/4" (6 mm) 1/2" (13 mm)

» This system should not be allowed to ﬂ oat; it must

be attached in a manner that secures the framing/

system.

» The sleeper system must be level and have no uneven

undulations. Any uneven areas of the substructure

will transfer to the Trex decking, resulting in uneven

decking.

» Trex, when used with a sleeper system, must be

supported below its entire length and if using in

a rooﬁ ng application, the supports must run the

direction of the pitch of the roof to facilitate proper

drainage. Sleeper should be placed perpendicular to

the deck board orientation.

» For Commercial applications it is recommended

to consult local building code ofﬁ cial for speciﬁ c

requirements.

» If installing decking at angle, decrease spans

4" (100 mm) for each of the above. (12" (305 mm)

for residential and 8" (204 mm) for commercial.)

» For sleeper systems where little debris (pine needles,

leaves, sand, dirt) can accumulate either between

or under deck boards, a minimum of 1-1/2" (38mm)

height is allowable. Trex recommended the use of

Trex Universal Hidden Fasteners or 2" Starborn

Cap-Tor

xd - Epoxy Coated screws. (NOTE: Trex

recommended composite decking screws are too long

when using 1-1/2" (38 mm) height as this will penetrate

through the sleeper.) For areas with the potential for

debris buildup, a minimum 3-1/2" (89 mm) or greater

height is recommended to allow the debris to be

removed along with the use of either Trex Universal

Hidden fasteners or any Trex recommended screws.

» ALWAYS consult your local building code authority

for proper details on roof and railing installation to the

roof structure if required.

» Any deviation from these recommendations could

result in the voiding of the Trex warranty.

A sleeper system is a substructure between a solid surface and Trex decking. Drainage, access, and airﬂ ow are

critical. Water must be able to ﬂ ow through and away from the deck. For repairs and removal of debris, joist system

access may be necessary.

Solid Wall

Attach sleeper/bearer

joists to stable substructure

(i.e. wall and/or concrete

Gap decking width-to-width 1/4" (6 mm)–3/8" (10 mm)

depending on temperature at installation

(See note below for more information.)

Code-approved bearer substructure

Minimum 1- 1/2" (38 mm) thick and

1- 1/2" (38 mm) in height

(See note below for more information.)

Gap decking from solid object (i.e. wall)

1/4"–1/2" (6–13 mm) depending

on temperature at installation

(See note below for more information.)

Trex Decking

Where Trex decking is end-to-end and meets at a joist,

add a “nailer or sister joist” at the butt joint of the decking.

This will allow ends of each board to rest on a seperate

joist and be attached properly.

Flat level surface (i.e. concrete)

DO NOT ATTACH to unstable

substructure such as concrete

blocks or pavers setting in gravel,

sand, dirt, etc.

Residential = No greater than 16" (407 mm) on center

Commercial = No greater than 12" (305 mm) on center

(See note below for more information.)