Benefits of Butyl Joist Tape vs. Asphalt Based Joist Tape
By Dave KileIf you’re interested in joist and bearer tape, you probably already know the immense benefits that come when you waterproof the timber on your deck with the right building products. Whether you’re building a composite deck or one with timber decking boards, your substructure (the bearers and joists holding up your deck) is likely to be timber.
Water leaking through your deck boards can cause hidden damage unless your bearers and joists are covered. While sealants are essential to protect your decking boards, you need protection for your timber substructure too.
Using a high-quality flashing tape can protect the top of the deck joist, rim joist, and ledger board from developing rot and timber decay. Flashing tape will hold water, and also help seal around screw holes and fasteners, to help prevent cracks.
The three main choices for deck flashing tape are butyl, asphalt or bitumen. What’s the difference and which should you choose?
Butyl or Asphalt Flashing Tape?
Bearer tape typically comes in three types: acrylic tape (G Tape), butyl and bitumen. Bitumen, made from petroleum and asphalt, will dry out over time, reducing the effectiveness of flashing. That leaves butyl or acrylic.
Butyl rubber tape has many advantages over an acrylic-based tape:
- It is stickier
- It endures less stain
- It has less high-temperature oozing
- It can be applied in a wide range of temperatures
- It is more rubbery than acrylic-based tape, allowing it to flow better around the deck screws and deck fasteners to create a tighter seal.
The net result: butyl tape provides superior weatherproofing for the timber foundation of your deck.
The Longevity of Deck Flashing Tape
You want a butyl adhesive that will last as long as your bearers and joists.
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 comes with only a 300-day warranty.
The average deck begins to experience water damage within 8 to 10 years. High-performance Trex Protect fights the rot and guards against costly future water damage — at a low cost. Protecting an average-size deck measuring 3.5m x 7.5m will require approximately five rolls of Trex Protect Bearer tape and one roll of Trex Protect Bearer Tape. For less than a $200 investment, your deck substructure can last as long as the decking it supports.
As with any item you are buying, cost comparisons alone may not be the right approach to selecting the best joist and bearer tape. It would help if you considered the full cost to protect your deck, which involves not only the price you pay but the quality of the tape. Bearer flashing tape is like your insurance policy on your deck substructure, so while you don’t want to bust your budget, you also don’t want to skimp on quality to get a slightly lower price.
Installation
Contractors or DIYers will tell you to buy a butyl tape that is easy to install and requires little trimming. A self-adhesive butyl tape that lies directly on the boards requires minimum cuts with little overlap.
When applying bearer tape to your bearers and joists, you want to be sure to purchase a tape that is not too thin and not too thick. With thin tape, you risk long-term durability of the tape. A thick tape can be difficult to install. Trex Protect is available in two widths: 40 mm x 20 m for joists and 100 mm x 20 m for bearers.
To find out exactly how much Trex Protect® Joist & Bearer Tape your project requires, use our Materials Estimator.
Step-by-Step Installation Instructions
Installing self-adhering bearer tape is a relatively simple process, with four main steps.
Begin by preparing your surface. Apply Trex Protect Joist & Bearer Tape to horizontal and vertical surfaces. This peel and stick flashing has two widths making it convenient to apply to double bearers and joists. For best results, install Trex Protect Tape when the temperature range is 10˚C or greater.
When pulling deck boards onto the deck, use a piece of plywood or wafer board to overhang the edge of the deck. This method will prevent the product from rolling up and pulling up from the joist.
- Clean the Joist Surface, making sure it is dry and free of debris.
- Remove the backing while applying the tape directly to the surface.
- Cut the tape to length with a utility knife or scissors.
Don’t let timber rot become the enemy of your beautiful outdoor living experience. As you begin deck building, don’t forget the bearer tape. This simple home improvement will provide hidden protection you can count on.
