Following assumptions are made:

  1. The post is pinned at the base and the post is pinned at the Trex® decking beam.
  2. Gravity load is transferred to the post by the box beam.
  3. Calculations were done for the maximum Trex joist span and maximum Trex cantilever length and maximum Trex box beam span.

    (See “Column Load Assumptions Table” below for maximum Trex span lengths used to obtain the loads on the columns.)

Column Selection Table — HSS posts for house-attached deck
Single BB Double BB
HSS Selection Dimensions (in) 3 1/2 x 3 1/2 x 1/8 5 1/2 x 5 1/2 x 1/8
* Column Load Assumptions Table – HSS posts for house-attached deck
Load Case (psf) 50 75 100 125 150 200
Max. Trex Joist Span to obtain loads on Columns 15 14 12 10 9 8
Max. Trex. Joist Cantilever Length (ft) to obtain loads on Columns 4 4 4 3 2.5 1
Max. Trex. DBL Box Beam Span to obtain loads on Columns 13.67 12.83 12.1 12.1 11.83 11.75
Max. Trex. SGL Box Beam Span to obtain loads on Columns 10.33 9.83 9.17 8.75 8.33 8.25

*Columns shown in the "column selection table" are based on assumed span loading shown in the "column load assumptions table." the "column load assumptions table" should not be used for selecting actual trex joists or box beam members as this information is provided separately.

  1. The Trex deck is attached to the main structure or house and the lateral loads have been designed to transfer though the connection to the main structure or house, therefore, there is no lateral load considered to transfer to the columns. The attachment of the steel track to the wood rim should result in the transfer of all of the lateral loads to the main structure or house. The design of the deck connection to house is not a part of the post design. Refer to the Trex Elevations® Installation Guide for detailed specifications regarding the connection.
  2. Yield stress of the steel is 46 ksi, A500 G (B) HSS square.
  3. Maximum height of post is 10'-0".
  4. Other assumptions are mentioned within the calculations.

DISCLAIMERS:

  1. If any of the installation conditions vary from the listed assumptions, an engineer should be contacted to specify the HSS post to be used.
  2. The base plate design and connection is not considered a part of the post design. These base plates and connections should be selected by others.
  3. Trex and Trex affiliates are not responsible for the foundation or geotechnical design.
  4. See Trex post warranty information for maintenance and required site conditions. Trex post cannot be placed below grade.