Is Deck Joist Tape Necessary?
Most decks are built with pressure-treated lumber, which is made of lumber that has been treated with a preservative to give it resistance to rot and pests. However, it’s still an organic material, and with time and moisture (a big problem around Seattle), even pressure treated lumber will decay.
Click to learn more about Pressure Treated Lumber
In treated lumber, the preservative isn’t able to penetrate fully to the center of boards, so penetrations into this area can allow water and microbes access to the less treated portions of the wood, and this can cause earlier decay of the structure. The tops of joists and beams also tend to collect water and debris, which further accelerates decay.
This is where joist tape comes in.
Joist tape provides a barrier on top of structural members to protect them from moisture, sealing around fasteners and helping extend the lifespan of your deck.
Joist tape isn’t absolutely necessary. We sometimes see decks with pressure treated lumber that is 20 years old and shows no sign of rot. However, when we do see rot, it typically starts where the decking fasteners penetrate into the framing, or where cut lumber ends butt tightly into another surface, trapping moisture.
So adding joist tape may prolong the life of your deck structure, possibly by 10 years or more, and with a relatively small cost. That’s why it’s standard on all Tool & Trade decks.
Deck Joist Tape Testing
We tested 7 joist protection and self-sealing flashing tapes and found that Nichigo G-Tape and Trex Protect Joist Tape outperformed the others in both adhesion and ease of use, and both passed our Leak Check Test with flying colors.
G-Tape was the easiest to use, applying effortlessly with great adhesion in most conditions.
Trex Protect was a bit harder to install, with packaging that was a bit difficult to remove and a liner that had to be dealt with, but it had the best adhesion of any tapes we tested, even sticking to a surface with oily residue. It also has a thicker, stretchier adhesive which really seals out moisture.
Nichigo G-Tape and Trex Protect Joist Tape are both stocked at Dunn Lumber.
*Your surface should be clean and relatively dry before applying joist tape, or you may have problems with adhesion.
Tapes Tested: Nichigo G-Tape, Trex Protect Joist Tape, Vycor Deck Protector, Vycor Plus Flashing Tape, Huber ZipSystem Seam Tape, Huber ZipSystem Stretch Tape, Henry FortiFlash Butyl Tape
