Want to keep your deck safe from rot without using standard joist tape? You’re not alone. Many homeowners wonder how to protect their deck joists so their deck lasts longer and stays strong.
Deck joist tape is a popular option, but it’s not the only one. In fact, there are many great alternatives that can seal joists, block water, and give your deck years of extra life.
In this guide, we’ll walk you through 8 deck joist tape alternatives, explain the pros and cons of each, and help you figure out which one fits your deck best.
Why Protect Your Deck Joists?
Think about how rainwater works. When it falls on your deck, water slips between the boards and often gets trapped on the joists below. Over time, that trapped water leads to rot.
It doesn’t stop there. Screw holes and metal fasteners also give water an easy way inside the wood, speeding up damage. To make matters worse, modern pressure-treated wood isn’t as resistant to rot as older lumber used to be. That’s why protecting joists is so important. A small step now can save you from costly repairs later.
8 Deck Joist Tape Alternatives
Butyl Rubber Tape
Butyl tape is a sticky, waterproof tape made for outdoor use. It is very durable, works well in both hot and cold weather, and does an excellent job of sealing screw holes. The drawback is the cost, since rolls usually range from $10 to $25, and once you place it down, it is difficult to adjust. This option is best for decks in tough weather conditions. If you choose butyl tape, go for a wider roll three to four inches to make sure your joists are fully covered.
Acrylic Tape (like G-Tape)
Acrylic tapes are lighter and cheaper, which makes them easier to work with. They are affordable, usually between $5 and $15 per roll, and they can be repositioned, which is a big help for DIYers. The downside is that acrylic tape is not as tough as butyl in extreme weather and may wear out faster. Still, it works well for small decks or budget projects in mild climates. For better results, look for UV-resistant acrylic tape so it lasts longer in the sun.
Bitumen Paint
Bitumen paint is a liquid that you brush or spray directly onto joists to block water. It is inexpensive, costing around $15 to $40 per gallon, and it covers large areas quickly, even joists with odd shapes. However, it can crack if the wood shifts, it is messy to apply, and it does not hold up well in sunlight. Bitumen paint is best suited for large decks or complex frames. Applying two thin coats instead of one thick one gives stronger protection.
Roofing Felt (Tar Paper)
Roofing felt, also called tar paper, can be cut into strips and stapled onto joists. It is very cheap, usually $10 to $30 per roll, and easy to find. Installing it is simple, but it does not offer the same waterproofing as tape and can wear out quickly in wet conditions. This makes it a better choice for budget decks in drier climates. To improve its performance, staple it tightly and overlap the edges so water has less chance of getting in.
Liquid Rubber Sealant (like Flex Seal)
Liquid rubber sealant is sprayed or brushed on, creating a flexible waterproof layer over joists. It is good at sealing around screws and works well on uneven surfaces. A gallon typically costs $20 to $50. On the downside, it can be messy, takes time to dry, and gets expensive for large decks. This method is ideal for older decks or tricky framing where tape does not stick properly. For a cleaner finish, apply it with a foam brush.
EPDM Shower Pan Liner
An EPDM shower pan liner is a thick rubber sheet normally used in showers, but it can also be cut to fit deck joists. It is extremely waterproof, very durable, and flexible enough to handle wood movement. The trade off is cost sheets usually run from $100 to $300 and installation can be difficult. This makes EPDM best for high end decks in wet or coastal areas. If you use it, practice cutting on scraps first with a sharp utility knife to avoid mistakes.
Roll-On Deck Frame Coating
Roll on deck frame coatings work like paint, covering joists completely. They are DIY-friendly, with prices ranging from $30 to $60 per gallon, and they cover edges and gaps that tape might miss. The downside is that they take longer to dry, are less flexible than tape, and may need to be reapplied over time. These coatings are a good choice for decks with complex framing or multiple joists. For best results, apply them on a dry day and let them cure fully before adding boards.
Ice and Water Shield
Ice and water shield is a roofing membrane that can be cut into strips for joists. It sticks well, is highly waterproof, and is easy to find for about $20 to $40 per roll. The drawback is that it is bitumen-based, which means it can damage PVC or composite decking. For this reason, it is better suited for wood decks in moderate climates. If you choose this product, always confirm it is safe with your type of decking material.
Pick the Best Joist Tape Alternative for Your Deck
So, which joist protection should you pick? The answer depends on a few key factors. If you are working on a tight budget, roofing felt or acrylic tape are the most affordable choices, while butyl tape or EPDM liners cost more but usually last longer. Weather also plays a big role. Homeowners in rainy or coastal areas will get better results with butyl or EPDM, while those in dry climates may find that simple tar paper is enough.
The size of your deck matters too. Large decks often benefit from liquid coatings or bitumen paint because they cover more surface area at once, while smaller decks can be protected easily with tape. Your level of DIY skill is another thing to consider. Beginners usually do better with easy-to-handle products like acrylic tape or roll-on coatings, while EPDM sheets require more cutting and fitting experience. Finally, always check your local building codes before making a decision, since some areas may have specific rules about what materials can be used.
Easy Steps to Get It Right
- Clean first: Wipe off dirt and sawdust so tapes and coatings stick well.
- Have tools ready: Utility knife for tapes, foam brush or roller for liquids.
- Seal tight: Overlap edges and seams so water can’t sneak in.
- Press down: Smooth tapes firmly to remove air bubbles.
Pick the right day: Avoid extreme heat or rain for best results.
Never Make These Mistakes
- Not cleaning the wood first – If your joists are dusty, wet, or dirty, the tape or coating won’t stick well. Always wipe them clean and let them dry before starting.
- Using tape that’s too narrow – Thin tape won’t fully cover the top of the joist, which means water can still get in around the edges. Choose a wider tape so the whole top is sealed.
- Mixing the wrong materials – Some products don’t work well together. For example, bitumen can damage PVC or composite decking. Always check that your tape or coating is safe for the decking you’re using.
- Working too fast – Rushing the job often leaves tape crooked, wrinkled, or with gaps. Take your time to apply it straight and press it down firmly.
- Ignoring screw and nail holes – Water often enters in through fastener holes. Make sure your tape or coating seals tightly around screws and nails to stop leaks.
Is Joist Protection Worth It?
Yes, it really is. Builders and tests show that sealing deck joists can add 5–15 extra years to a deck’s life. Why? Because modern lumber rots faster, especially around screws and nails. A small investment in protection today saves you from paying thousands later for repairs or replacements.
At LHC Services, we’re more than just builders. We’re deck experts in Richmond who care about durability, safety, and happy customers. Whether you need a brand-new deck, repairs, or advice on protecting your frame, we’ve got you covered.
Conclusion
You’ve now seen 8 strong alternatives to standard deck joist tape. From simple roofing felt to heavy-duty EPDM liners, there’s an option for every budget, climate, and skill level. Take your time, pick the product that fits your deck, and protect your investment the smart way. If you want expert help, LHC Services is here for you. We build decks designed to last and can guide you on the best joist protection for your project.
Frequently Asked Questions
Yes, you can use ice and water shield instead of joist tape. It’s sticky, waterproof, and costs around $20–$40 a roll. You just cut it into strips and place it on the joists. It works well in normal, not-too-extreme weather. But here’s the catch: it’s made with bitumen, which can hurt PVC or composite decking. For wood decks, it’s a safe and strong choice that keeps water out.
If your deck is old or the wood is rough, tape can peel off. In that case, a liquid option works better. Liquid rubber sealant (like Flex Seal) or a roll-on deck frame coating (like FastenMaster) are good picks. You can brush or roll them on, and they flow into cracks and around screws. They bend with the wood as it moves, so they don’t break. Just apply on a dry day with a foam brush, and you’ll get a neat, tough layer.
Good news is tapes like butyl rubber don’t trap water. Instead, they block it from getting into the wood. At $10–$25 a roll, they stick well in hot and cold weather and seal up screw holes so water can’t sneak in. Builders and tests show it really works, helping your deck last years longer. Just make sure the joists are clean before you stick it on.
Yes, you don’t always have to use tape. One strong choice is EPDM shower pan liner. It’s a thick rubber sheet that you cut into strips. It’s tough, waterproof, and great in rainy or coastal areas. It costs more ($100–$300 a sheet) but lasts a long time. Another option is bitumen paint. It’s cheap and easy to brush on, especially for joists with odd shapes. Just remember it can crack if the wood moves, so use thin coats.
Yes, you can. Foundation coatings or wood sealers (like elastomeric sealers) work well. You brush them on, and they cover the whole joist, even the screw holes. A gallon costs about $20–$50. They’re easy for beginners and don’t need the wood to be super clean, but they take longer to dry. Many builders say they keep water out and stop rot, so they’re a smart backup if tape feels too tricky.