Let’s talk about an increasingly popular innovation in the decking industry: deck joist tape. This topic has been gaining traction, and it’s important to understand its uses, benefits, and potential drawbacks.
What is Deck Joist Tape?
Deck joist tape is a protective adhesive tape applied to the top of deck joists, beams, and ledger boards to help prevent damage from the elements, especially moisture. It is typically made from either butyl, asphalt, or acrylic-based materials, providing a waterproof barrier that extends the lifespan of the wooden framing beneath your deck.
Deck framing is often constructed from pressure-treated lumber, which, while durable, is still susceptible to moisture penetration over time. Without protection, prolonged exposure to water can lead to rot, decay, and even structural failure. Applying deck joist tape is a simple yet effective way to mitigate these risks.
Types of Deck Joist Tape
1. Butyl-Based Joist Tape
Butyl joist tape is the most common type used in deck construction. It is thick, sticky, and highly effective at sealing wood against moisture. Some of the key characteristics include:
- Durability – Once applied, it adheres permanently to the wood surface.
- Waterproofing – Forms a strong seal that prevents water intrusion.
- Weather Resistance – Withstands extreme temperatures and exposure to the elements.
However, butyl tape requires careful application. Once the backing is removed, it must be placed correctly, as repositioning can be nearly impossible. If two sticky sides of a strip of this tape touch, there is no seperating them, and the strip becomes waste.
2. Acrylic-Based Joist Tape (G-Tape)
Acrylic-based joist tape, like G-Tape by Mitsubishi Nichigo, is a newer alternative that has gained popularity due to its ease of use. Key benefits include:
- Repositionable Application – Unlike butyl tape, acrylic tape does not stick to itself permanently, making it easier to handle. The full adhesive properties of this tape increase over time, and are fully set in a few hours, depending on the environmental temperatures.
- Tears easily – Can be torn by hand, unlike butyl tape, which requires a knife or blade.
- Weather and Temperature Resistance – Performs well in extreme temperatures.
G-Tape has become a favorite among contractors because it simplifies installation without sacrificing durability or effectiveness.
Alternative Option: Roll-On Deck Frame Coating by FastenMaster
Another effective solution for protecting your deck framing is the Roll-On Deck Frame Coating by FastenMaster. This product offers a liquid-applied roll-on alternative to joist tape and is ideal for those looking for a full-coverage method of sealing their framing components.
What is It?
FastenMaster’s Roll-On Deck Frame Coating is a durable, elastomeric coating designed to be applied directly to the top and sides of deck joists, beams, and ledger boards. Once cured, it forms a waterproof barrier that seals the surface against moisture and UV exposure.
Key Benefits:
- Full Coverage Protection – Covers the entire surface, including edges, corners, and gaps where joist tape might not reach.
- Easy Application – Can be rolled or brushed on like paint, making it simple for DIYers and professionals alike.
- UV Resistant – Unlike some joist tapes, it provides protection from sun damage.
- Adheres to Damp Wood – Allows for greater flexibility in weather conditions during application.
- When temps are warm, coating can be ready for decking in 30-60 minutes.
When to Use It
This coating is ideal for complex deck designs or areas where tape might be difficult to apply. This product is great for intricate blocking work on stairs, box steps, or heavy framing with sistered beams or joists.
Why Use Deck Joist Tape?
1. Protection Against Moisture Damage
The primary function of deck joist tape is to protect wooden framing from moisture exposure. Water that seeps between deck boards can sit on the joists, leading to mold, mildew, and rot. Joist tape provides a waterproof barrier that prevents this from happening.
2. Extending the Lifespan of Your Deck
High-quality composite decking materials often come with warranties ranging from 25 to 50 years. However, if the frame underneath deteriorates due to moisture damage, the deck’s longevity is compromised. Joist tape ensures the framing has a change to lasts as long as the decking itself.
3. Preventing Fastener Corrosion
When fasteners penetrate untreated wood, moisture can seep into these small openings, causing screws and nails to rust. Joist tape self-heals around screws and nails, creating a seal that reduces corrosion.
4. Cost-Effective Insurance
Applying joist tape is a relatively low-cost investment compared to the potential cost of deck repairs or replacement. A standard roll of deck joist tape ranges from $20 to $50, and an entire deck can be protected for a few hundred dollars.
Choosing the Right Width and Size
Deck joist tape comes in a variety of widths to accommodate different framing components. Common sizes include:
- 1 5/8″ to 2″ – Ideal for standard joists.
- 3″ to 4″ – Suitable for double beams and wider surfaces.
- 6″, 9″, and 12″ – Used for larger posts, blocking, and stair framing.
Manufacturers like Trex, Camo, and G-Tape offer multiple sizes to fit various decking needs.
How to Apply Deck Joist Tape
Applying deck joist tape is a simple process that requires minimal tools and effort. Follow these steps for optimal results:
Step 1: Prepare the Surface
Ensure the joists are clean and dry before application. While some tapes adhere well to slightly damp surfaces, a dry joist ensures the best adhesion.
Step 2: Measure and Cut (or Tear)
Cut the tape to the appropriate length. If using G-Tape, you can tear it by hand. For butyl tape, use a utility knife for precise cuts.
Step 3: Apply the Tape
Remove the backing (if applicable) and press the tape firmly onto the top of the joist. Ensure it covers the full surface and overlaps slightly on the edges.
Step 4: Smooth and Secure
Use a roller or hand pressure to smooth out any air bubbles and ensure full adhesion.
Common Mistakes to Avoid
- Applying Tape to Wet Wood – Butyl tape may not adhere properly to damp surfaces.
- Not Covering the Entire Joist Surface – Leaving gaps can allow water infiltration.
- Using the Wrong Width – Using too narrow tape can limit its protective effect.
- Not Pressing the Tape Firmly Enough – Ensuring a strong bond prevents peeling or lifting over time.
Is Deck Joist Tape Worth It?
In our professional opinion at The Deck Supply, deck joist tape is an invaluable addition to any deck construction project. For a relatively small investment, you can add years of life to your deck’s framing, ensuring that moisture doesn’t compromise your structure.
While both butyl and acrylic-based tapes offer excellent protection, your choice will depend on your preference for ease of use versus ultimate adhesion. G-Tape is ideal for those looking for a mess-free application, while butyl tape remains a strong choice for those seeking maximum durability.
Alternatively, if you’re looking for full-coverage protection, FastenMaster’s Roll-On Deck Frame Coating is an excellent option. It delivers long-term moisture and UV protection and is a great solution for complex or intricate deck framing.
Conclusion
Deck joist tape is an affordable and highly effective way to protect your deck’s framing from moisture damage, rot, and fastener corrosion. Whether you choose butyl or acrylic-based tape, or opt for FastenMaster’s roll-on coating, you’ll be making a smart investment in the longevity of your deck.
If you have any questions or need recommendations, feel free to reach out to us at 866-8-ON-DECK or email us at info@thedecksupply.com. You can also browse our selection of deck joist tape and frame coatings on TheDeckSupply.com.
Protect your deck today—because a strong foundation is the key to a lasting structure!
