What Is Butyl Tape?
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When you need an adhesive or sealant, you want the best one to get the job done. If you’re building a new deck, butyl tape can add years of safety and usefulness to your home improvement. Butyl tape provides a protective barrier against the moisture and condensation that seeps through the decking boards when it rains or snows, keeping your wood stronger for the long run.
Let’s get down to the sticky details!
What Is Butyl Tape?
Adhesives come in three main varieties: silicon-based, rubber-based, or acrylic-based. In addition, you can find both natural and synthetic rubber adhesives.
This article focuses on butyl adhesives, part of the rubber-based category. Butyl was developed to augment traditional rubber adhesives. Butyl tapes are less temperature-sensitive and maintain their stickiness at much lower temperatures than natural rubber.
With butyl rubber tape, you find a tape that instantly adheres to most surfaces and has a high adhesion level. Due to its flexibility bonds well in applications where moisture is a factor, such as with decks. In addition, homeowners and builders appreciate how quickly they can repair with butyl seal tape.
What are the Uses of Butyl Tape?
When might you use this flexible adhesive? You can use Butyl tape in a variety of situations:
- RV butyl putty tape (for a camper)
- Small home repairs
- With glass or metal, including ductwork
- On a wide range of surfaces, including wood, it is an excellent choice for deck substructures.
What are the Pros and Cons of Butyl Tape
Of course, with any tool, there are advantages and disadvantages. Let’s start with the pros.
Butyl tape:
- Securely bonds to even resistant surfaces
- It is less temperature-sensitive and oozes less in high temperatures
- It can be applied in a wide range of weather conditions — very flexible
- It is more affordable than acrylic or silicone in most instances
- Provides an effective barrier that is airtight and watertight
- Flows better around decking screws and deck fasteners, creating a tighter seal.
However, no adhesive is perfect. Butyl tape and butyl sealant also have cons:
- Because it is solvent-based, it can dissolve if exposed to strong solvents such as gasoline, turpentine, or mineral oil
- It does not adhere well if the surface is very rough
- Though it has improved, it can be affected by extreme temperatures
Butyl tape is best used during construction. However, if a sealant is needed after construction, such as around a window frame, you may need caulk or other material that works like caulking.
A deck’s substructure, its beams, and joists can start to rot around 8 to 10 years, even with treated lumber. Therefore, ensure your deck’s substructure lasts as long as the deck boards it supports with butyl tape.
Water leakage through your decking boards can cause hidden damage unless your beams and joists are covered. Even tiny cracks around screws and can lead to wood rot. For a small cost, you can protect your deck substructure by applying flashing tape. Trex Protect can waterproof the tops of the deck joists, rim joists, beams, and the ledger board. It will hold water out and help seal around screw holes and metal fasteners to prevent corrosion.
Which Butyl Tape Should You Buy? 
Butyl tapes are often considered an all-in-one solution due to their many application uses. It is compatible with these surfaces:
- Glass
- Rubber roofing
- Metal roofing
- Wood
- Galvanized
- Aluminum
- Metal
- Plastic
The flexibility, strong adhesion, and weatherproof nature of butyl tape make it the perfect choice to be deck flashing tape. When considering which butyl tape to purchase, consider these factors:
- What is easier to install? Purchase a self-adhesive butyl tape that is easy to install. Because of its strong adhesion, you want to put the tape down once on a dry surface. Pick one that installs directly on the boards and requires minimum cuts and overlap. Additionally, go for a tape that’s not too thick (which will be difficult to install) and not too thin (which won’t be as durable).
- What about durability? Choose heavy-duty adhesive tape with an excellent warranty. Trex Protect Joist & Beam Tape comes with a 20-year warranty backed by Trex, the World’s No. 1 Decking brand. Newer products don’t enjoy this kind of track record.
- What is the cost? Protecting your joist, beams, and deck support posts should not cost a fortune. At the same time, cost comparisons on Amazon may not be the right approach.
Look at the total cost to protect your deck and the value of the warranty — and peace of mind — when choosing a quality product.
“Man is a tool-using animal,” said Philosopher Thomas Carlyle. “Without tools, he is nothing; with tools, he is all.” So get the right tool to protect your deck with excellent butyl tape!
How to Properly Install Butyl Tape
To begin, choose a tape that is easy to install and requires little trimming. For example, a butyl tape that lies directly on the deck boards will require minimum cuts. Trex Protect® can be applied to horizontal and vertical surfaces and comes in two widths.
To find out exactly how much tape your project requires, use our Materials Estimator.
Installing joist tape has just a few straightforward steps, detailed below:
- Prepare. Pay attention to application temperatures. The tape will seal when the product warms above 40˚F. Trex Protect works really well in high temperatures. It is best applied to a dry surface.
- Clean the joist surface, making sure it is dry and free of debris.
- Remove the butyl tape backing while applying directly to the surface. Run your hand over the tape and firmly press it onto the joists.
- After covering all horizontal and vertical surfaces, cut the tape to length with a utility knife or scissors.
A deck’s strength is in what lies beneath. To keep your wood substructure from succumbing to the ravages of rot, you’ll want to protect it from the start with joist tape. This small investment upfront will pay you back with more years on deck and more peace of mind.
