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

When you add a deck to your home, you’re not just adding outdoor living space. You’re making an investment. According to HomeAdvisor, a 200- to 500-foot deck can cost you around $7,000.

Why do You Need Joist Tape?

According to research, we conducted with builders, over 90 percent of a deck substructure starts to split and rot at around 8 to 10 years. The boards supported by that substructure are usually warranted to last about 25 years. If you want your deck to be safely supported by its substructure for the life of the deck, you can protect your investment for a minimal extra cost.

Joist tape is an affordable way to protect your deck substructure. Peel-and-stick flashing tape allows the wood to breathe because it is applied as a cap directly on top of joists and beams. The tape protects screw holes from moisture by acting as a barrier. Joist tape will protect your substructure from decay to guarantee your foundation lasts as long as your deck.

What to Shop for in Joist Tape

Here are some things to consider when shopping for the right joist tape to protect your investment.

  • Material - Asphalt and butyl are the two main types of joist tape. Look for a butyl tape, like Trex Protect, because it has less high-temperature oozing, endures less stain, is stickier and can be applied in a wide range of temperatures. Butyl tape also creates a tighter seal around deck screws to prevent moisture from seeping in.
  • Ease of installation - Butyl tape requires little trimming because it lies directly on the boards, requiring minimal cuts and having little overlap. This makes it simple and quick to install.
  • Thickness - The joist tape you select should be just about a perfect fit on the deck boards. Tape that is too thick is difficult to install because it will require trimming. Tape that is too thin may not be as durable over time.
  • Price - You want a joist tape that is affordable, but you are also shopping for high quality. Remember that this is like your insurance policy on your deck substructure, so while you don’t want to bust your budget on joist tape, you don’t want to skimp on quality to get a slightly lower price.
  • Reputation - You could choose from several brands of butyl joist tape. The chart below gives you a comparison. Trex Protect is the leading joist and beam tape on the market and it comes with a 20-year warranty from Trex, the world’s number 1 decking brand!

Joist Tape Table