Joist tape (double-joist) applied to top of deck understructure

Joist tape (double-joist) being applied to deck joists

Joist tape (single-joist) applied to top of deck understructure

Joist & Flashing Tape

Self-adhesive butyl tape for composite or wood decks

Protect and maximize the life of your deck by using joist and flashing tape on a wood or composite deck's substructure.

  • Available Sizes: 1-5/8 in. x 50 ft. (for single-Joist) and 3-1/8 in. x 50 ft. (for double-Joist/beam)
  • Can be applied to the top of joists, rim joists, and ledgers to protect wood against water damage
  • Increases the holding power of deck screws
  • Acts as a barrier to protect screw holes from moisture
  • Ideal for both wood and composite deck understructures for which we recommend using ProWood® professional grade treated lumber

Installation Instructions


Yes. Deckorators decking must be gapped at the ends to allow for expansion and contraction and gapped between boards for water runoff. At the ends of the deck boards, allow a minimum of 1/16" gap for every 20°F of difference between the installation temperature and the hottest temperature expected. Allow a 1/4" gap between the deck boards and between all decking and any permanent structure or post for water runoff. For more information, refer to the installation instructions.

Deckorators composite decking, manufactured by UFP Ventures II, Inc., has been evaluated by ICC-ES to be code compliant with details listed under the PFS-TECO RR-0100 Evaluation Report (pdf - 1 MB). The structural performance of the Deckorators CXT railing system has been tested and evaluated by professional engineers at an independent third-party test laboratory known as Architectural Testing Inc (ATI). The results demonstrate that the different combinations of the Deckorators railing system as noted in ATI's CCRR Report 0171 complies with 2012 International Building Code; 2012 International Residential Code; ICC-ES AC174 effective January 2012; ASTM D7032-08; and ANSI Z97.1-2009.

A clear 2" space between the bottom edge of the joists and grade is recommended to allow proper ventilation.