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. For a 400 sq foot deck, it can cost between $12,000 and $24,000 for composite decking, and between $10,000 to $17,000 for a wood deck.
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!

How to Decorate Deck Support Columns
Browse some examples of decorative deck support posts for tall decks.
Beam Span Chart
Learn how to size your deck beam using this easy-to-use span table. Just cross-reference the post spacing and joist length to determine the beam size.
Decking Patterns
Installing your decking at a 45-degree angle is a popular style for decks. This can be done to reduce decking seams or just for appearance.
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Install a picture frame or perimeter board to finish the edge of your deck with style.
Dos & Don'ts for Homeowners to Consider When Building a Deck
Your dream deck can take whatever shape you like. The trick is making it fit your budget and site conditions. While the deck doesn’t have to be built as a rectangle, there could be good reasons for doing just that.
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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. For a 400 sq foot deck, it can cost between $12,000 and $24,000 for composite decking, and between $10,000 to $17,000 for a wood deck.
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!

How to Decorate Deck Support Columns
Browse some examples of decorative deck support posts for tall decks.
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Explore Articles by Topic

Footings
Information related to installing frost footings for decks

Framing
Learn structural framing methods

Decking
Learn about wood and composite decking materials

Stairs
An in-depth look at the complex issue of how to build stairs

Railings
How to install guardrails and handrails to meet IRC code

Features
An overview on water drainage, benches, planters and lights

Design
The basics of deck design

Planning
Learn about permits and working with contractors

Porches & Patios
Build a covered deck to enjoy all seasons

Ledger
Proper attachment techniques

Care
Maintain your deck to maintain your investment

Materials
An overview on water drainage, benches, planters and lights