Joist Tape: What Is It and Do I Need It?

When building or upgrading a deck, most homeowners focus on visible features like boards, rails, and lighting. But what lies beneath the surface is just as important. One small but powerful product that can significantly extend the life of your deck is joist tape.

Joist tape is a waterproof, adhesive-backed tape that’s applied directly to the tops of joists, beams, and ledger boards before deck boards are installed. Its main job is to prevent moisture from penetrating the wood framing, which is especially vulnerable to water damage over time.

1. How Joist Tape Works
Deck joists are typically made of pressure-treated lumber, which is resistant to decay but not immune. When water gets trapped between the decking and joists, it can sit there for days after rain. Joist tape creates a moisture barrier, sealing the top of the joist and the screw holes where water might otherwise enter.

2. Benefits of Using Joist Tape
The biggest advantage is protection from rot, mold, and structural weakening. By keeping water out of the wood, joist tape helps your deck frame last longer. It also reduces the risk of corrosion in metal fasteners and hidden brackets, which adds to the longevity of the entire structure.

3. When to Use Joist Tape
Joist tape is highly recommended when installing composite or PVC decking, since these boards often outlast the wooden frame underneath. If you’re building a new deck with a high-end surface, it makes sense to protect the substructure too. It’s also a smart addition during resurfacing projects where the frame is still in good shape and being reused.

4. Is Joist Tape Worth It?
Joist tape adds a small amount to the overall cost of your deck but can save you thousands in repairs over time. It’s a low-cost, high-impact solution for protecting your investment. When installed correctly, it stays in place for decades and requires no maintenance.

5. Installation Tips

• Apply joist tape to dry, clean joists
• Cover the top of every joist, beam, and ledger
• Wrap it over the sides slightly for better protection
• Press firmly to bond and trim the excess
• Puncture holes for screws—no need to pre-drill

Conclusion
Joist tape may not be the most visible part of your deck, but it plays a major role in keeping your structure solid and safe for years to come. At North Georgia Elite Decks, we always recommend joist tape for clients who want long-lasting performance and maximum value. Contact us to learn more or include it in your next deck build.