Installation Guide

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DECKING

ROOFTOP AND SLEEPER DECK SYSTEMS

Sleeper Deck Systems

A sleeper system is a buffer between a solid surface

and Trex

decking. Drainage, access, and airﬂow are

critical. Water must be able to ﬂow through and away

from the deck. For repairs and removal of debris, joist

system access is necessary. Good airﬂow will keep the

decking dry and in good condition.

Trex, when used with a sleeper system, must be

supported below its entire length and if used in a

rooﬁng application, the supports must run the

direction of the pitch of the roof to facilitate proper

drainage. In addition, sleeper joists must be attached

to the roof structure in a manner that stabilizes the

deck frame. Failure to do so may result in a poor

structure which will compromise deck performance.

In areas of application where a sleeper system is

required that would not be susceptible to excessive

debris buildup (examples would include covered areas

such as balconies, porches, etc.), a minimum height

of 1-1/2" (3.8 cm) for pressure-treated joists as well as

a minimum 1/4" (0.6 cm) gap between Trex decking

would be acceptable. These areas would still have to

be designed to allow for proper drainage and hidden

fasteners would be acceptable. However, if access to

the structure under the decking is required, it would

be recommended to use either the Universal Fastener

(plastic) or 2” (5.1 cm) composite decking screws. A

1 /4" (0.6 cm) to 1/2" (1.3 cm) gap is still required when

abutting walls or other ﬁxed objects.

In all other areas where there could be excessive water

buildup along with debris buildup, Trex would still

recommend a minimum height of 3-1/2" (8.9 cm) for

pressure-treated joists, as well as a gap of 3/8"

(1 cm). For this application, hidden fasteners would not

be recommended and standard 3" (7.6 cm) composite

screws would be used.

ALWAYS consult your local building code authority for

proper details on roof and railing installation to the roof

structure if required.

SPECIAL PATTERNS

When planning a unique pattern, you will need to adjust the framing to support the surface pattern. Refer to the

span and gapping charts on pages 19 and 20. Many decks are designed to take advantage of angles, as shown

below.

Herringbone Pattern Tile Pattern Picture Frame Pattern

ROOFTOP DECK TIPS

» If you want to access the roof, you must build

rex deck in removable sections or with

removable fasteners.

» You must attach the sleeper joists to the roof

tructure so that they stabilize the deck frame.

Failure to do so may result in a poor structure

hich will compromise

eck performance.

At a 60° angle, maximum

joist spanning is 2"

(5.1 cm) less than listed in

the chart below.

60°

Perpendicular to joists.

See chart below.

90°

At a 45° angle, maximum

joist spanning is 4"

(10.2 cm) less than listed

in the chart below.

45°

At a 30° angle, maximum

joist spanning is 1/2 of

the distance listed in the

chart below.

30°

CODE COMPLIANCE

Joist Spanning for Decking

Trex

decking meets all applicable national model

building codes. The joists must be spaced on center

according to the chart below. Be sure that joists are

level and plumb. Trex decking must span at least three

joists. For heavy items such as hot tubs, planters,

etc., consult a local building engineer or inspector

for span recommendations. If you want to minimize

the appearance of joists through the spaces between

boards, paint the top of your joists black.

Code Listings

Trex complies with major model building codes and

has been evaluated by the International Code Council

evaluation service.

Trex Complies with these Model Building

Codes:

» 1997 Uniform Building Code (UBC).

999 Standard Building Code (SBC).

» 2006 International Residential Code (IRC).

006 International Building Code (IBC).

» International One and Two Family Dwelling Code 1998.

OCA

National Building Code/1999 (BNBC).

rex decking is included in the National Research

Council of Canada’s Registry of Product Evaluations.

ee trex.com for CCMC Evaluation Report 13125-R.

For an Materials Safety Data Sheet (MSDS), please visit

trex.com

TREX DECKING SPAN CHART (On Center)

Commercial Decks,

Boardwalks and Marinas

Residential Decks, Light Duty Docks,

Residential/Day care Playground

Decking Loading 100psf (4826 Pa) 100psf (4826 Pa) 200psf (9576 Pa)

1" (2.5 cm) Boards 16" (40.6 cm) 16" (40.6 cm) 12" (30.5 cm)

2" x 6" (5.1 cm x 15.2 cm) Boards 24" (70 cm) 24" (70 cm) 16" (40.6 cm)

Maximum Railing Span for all Applications (on center of posts)

Transcend Railing 96" (244 cm)

Designer Railing/ 72" (183 cm)

Traditional Railing

Trex Accents Fire Defense

and Trex Escapes

Trex Accents Fire Defense

* and Trex Escapes

boards meet California and San Diego ﬁre code requirements. For California,

the requirements are that the board meets ASTM E84 Class B Flame Spread and 12-7A-4 Part A Underﬂame requirement. For

San Diego, the requirements are that the board meets 12-7A-4 Part A Underﬂame and Part B Burning Brand (all parts).

Trex

Escapes meets ASTM E84 Class A Flame Spread and CA SFM 12-7A-4 Underﬂame and Burning Brand requirements.

For more information, e-mail

question@trex.com

or call 1-800-BUY-TREX (1-800-289-8739). Trex Transcend

Lava Rock and

Spiced Rum are compliant with the Wildland-Urban Interface, California State and San Diego County ﬁre codes.**

ADJUST JOIST SPANNING TO ACCOMMODATE

ANGLED DECKING PATTERNS*

TREX RAILING SPAN CHART

* Only available in select areas.

** ASTM E84 Class B Flame Spread and CA SFM 12-7A-4 Underflame and Burning Brand requirements.