What is Joist Tape and Why Should I Care?

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, 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. Your deck can last plenty long without it, but it’s a relatively small cost that goes a long way to protecting your investment and minimizing structural repairs over time. That’s why it’s a standard on all of our decks.

Pro-tip: We prefer Nichigo G-Tape, it’s fairly priced, tears like duct tape, and sticks better than any other tape we’ve tried including Trex Protect and Vycor Deck Protect. It’s also available in 2”,4”,6” and 2” unlined rolls (the liner paper slows things down and makes a mess to clean up). Lumber should be relatively dry (and clean) before applying joist tape, or you may have problems with adhesion.