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TREX Products
TREX Decking Installation Guidelines

TREX® Decking Installation Guidelines

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 the 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 the boards, paint the tops of your joists black.

Code Listings
Trex complies with major model building codes and has been evaluated by the International Code Council evaluation service.

For an Materials Safety Data Sheet (MSDS), please visit www.trex.com

TREX DECKING
TREX DECKING

TREX DECKING SPAN CHART (On Center)
 
Residential Decks,
Light Duty Docks,
Residential/Day Care Playground
Commercial Decks,
Boardwalks and Marinas
Deck Loading
100 psf = 4.8 kN/m2
100 psf = 4.8 kN/m2 | 200 psf = 9.5 kN/m2
1" Boards
(including Porch)
16"
      16" 12"      

TREX RAILING SPAN CHART
 
Maximum Railing Span for all Applications
Transcend Rail
96" on center

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 guidelines.
  • Maximum allowable perpendicular overhang for Trex is 4"for non-walking surfaces only.
  • All decks require air circulation to keep them dry and looking good. To improve airflow, leave openings under the decking or increase gapping to 3/8".

WIDTH-TO-WIDTH GAP
Above 40°F*
Below 40°F*
1/4"
1/4"

*- Temperature at installation.

END-TO-END/END-TO-WIDTH AND ABUTTING GAP
 
End-to-End/
End-to-Width
Abutting
Above 40°F*
1/8"
1/4"
Below 40°F*
3/16"
1/2"

*- Temperature at installation.

When you use the recommended hidden fasteners, the placement of the hidden fastener establishes the designated gap size.

When installing fascia, gapping rules must apply.

TREX DECKING

Width-to-Width
The minimum required width-to-width gapping is 1/4". This is allowed for both hot and cold weather installations. For docks and heavily wooded areas, Trex recommends a 3/8" gap as well. No gapping should ever exceed 1/2".

TREX DECKING

End-to-End, End-to-Width
Gap Trex decking end-to-end, based upon the temperature at installation. See chart above.

TREX DECKING

Abutting Solid Objects
When decking is abutting a wall, you must gap it 1/4" - 1/2" depending upon the temperature at installation. See chart above.

STAIRS

Stairway Detail
  • Stair treads built with Trex meet requirements by the major national building codes. Consult your local municipality for specific requirements.
  • Fasten stair treads continuously across at least four stringers.
  • See chart at right for center-to-center spacing of profiles.
  • Dress the sides of stringers and risers with Trex fascia or trim for a finished look.
  • Most model building codes require the stair treads to be constructed under the following requirements:
    • Stairways must be at least 36" wide*
    • Stair treads must be at least 11" deep
  • Gapping between Trex boards on stair treads must be 1/4" - 3/8".
  • The overhang of the stair treads is not exceed 1/2".

*-For railings that are installed directly over stair treads, the stair treads must be larger than 36" wide. Refer to local building code regulations for details prior to installing stairs and railings.

NOTE: Trex rails meet 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.

MAXIMUM SPACING ON CENTER OF STAIR STRINGER
Transcend 1" x 6"
Actual dimensions: .94" x 5.5"
12"
Select 1" x 6"
Actual dimensions: .82" x 5.5"
9"

TREX DECKING

Decking Installation Page 3

Decking Installation Page 1

Trex Transcend Decking


TREX Transcend
Transcend Rail available in many colors

Other Trex Products:

Enhance Decking

Select Decking

Transcend Porch Flooring

Trex Rail Lighting

Trex LED Post Lights

Trex LED Rail Lights

Trex LED Riser Lights

Trex LED In-Deck Lights

 
Trex LV Transformers

Trex Remote Dimmer

Trex 6-Way Splitter

Trex Wire Packages

Trex Female Adaptor

 

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