How Do You Apply Joist Tape?

A deck’s beauty may exude from its boards, railings, and design, but its strength is in what lies beneath. To keep your wood substructure from succumbing to the ravages of rot — whether you choose to build a hardy ipe wood or low-maintenance composite deck — you’ll want to protect it from the start with joist tape.

This small investment up front will pay you back with more years on deck and more peace of mind. A quality joist tape can protect the top of the deck joist, rim joist, and ledger board from water infiltration, as well as helping seal screw holes and fasteners. 

How Do you Apply Joist Tape?

Before you apply, you’ll need to buy—our advice: choose a tape that is easy to install and requires little trimming. A butyl tape that lies directly on the deck boards will require minimum cuts. Trex Protect® Joist & Beam Tape can be applied to horizontal and vertical surfaces and comes in two widths.

To find out exactly how much joist tape your project requires, use our Materials Estimator.

Installing joist tape has just a few straightforward steps, detailed in this video. You can also find a summary of the instructions below:

1. Prepare. Clean the surface, ensuring it is clean and free from debris. 
2. Remove the butyl tape backing while applying directly to the surface. Run your hand over the tape and firmly press it onto the joists and beams.
3. Apply Trex Protect to all the joists, rim joists, beams, stringers, support posts, and the ledger board. After covering all horizontal and vertical surfaces, cut the tape to length with a utility knife.

It can also act as a barrier between wood and galvanized metal, such as joist hangers. 

Benefits of Deck Joist Tape

The best benefit of deck joist tape is the overall health and durability of your deck. It can save you on future maintenance and replacement costs. Joist tape extends the life of your deck and improves your deck’s structural integrity. 

Along with protecting your wood, it can keep your metal hangers from corroding. Because copper is used in the process of treating wood, the dangers of corrosion in metal fasteners are even greater. 

When to Use Joist Tape

Applying joist tape should be a must for any builder or homeowner wanting to DIY a new deck. If you want your deck to last, you’ll want to prevent moisture from penetrating your joists and be sure your deck substructure lasts as long or longer than your new composite decking boards.

What to Consider Before Buying a Deck Joist Tape

The three main choices for deck flashing tape include butyl, rubberized asphalt, and bitumen. What’s the difference and which should you choose?

Bitumen, made from petroleum and asphalt, will dry out over time, reducing its flashing effectiveness. That leaves butyl or acrylic adhesive as better choices, but butyl as the best choice. 

Butyl rubber tape has many advantages over acrylic-based tape. It is sticker, has less high-temperature oozing, can be applied in a wide range of temperatures, and is more rubbery than acrylic-based tape. Butyl tape flows better around the deck screws and deck fasteners. Overall, butyl tape provides superior weatherproofing for the wood foundation of your deck.  

Trex Protect is guaranteed to withstand the test of time. It comes with a 25-year warranty, so it lasts as long as the decking it supports. Acrylic tape typically comes with only a 300-day warranty.  

For a comparison of top joist tapes on the market, including Trex Protect, Deckwise Wisewrap, and Vycor Deck Protector, check out our blog or this comparison by Decks.com. 

Don’t begin your deck building without flashing tape. It’s a home improvement investment worth its weight in peace of mind.