MOLYLY Butyl Deck Joist Tape (1-5/8 in x 50 ft) — 12 Rolls Waterproof & Anti-Corrosion Sealing Tape
Product description
If your outdoor deck, shed, or roof framing needs a tougher barrier against water, MOLYLY’s butyl deck joist tape is built for sealing the gaps where moisture likes to sneak in. It’s a self-adhesive joist tape aimed at protecting wood structures and helping extend how long they hold up, especially in wet conditions.
That said, it’s not a magic fix for every problem—on paper it’s a sealing tape solution, so it works best when the surface is prepared properly and you’re using it where a tape-style seal makes sense.
What it is and what it’s for
This product is a butyl joist tape for decking and outdoor construction uses. The “joist tape” concept is simple: you run the adhesive strip along the framing/joist area to help form a continuous seal that improves water resistance and can reduce deterioration over time.
It’s described as waterproof and anti-damage, with a focus on protecting wooden deck structures. It’s also positioned as a flexible seal you can apply to different base materials, including wood and metal, which is helpful if your project mixes surfaces.
A practical way to picture it: before you close up deck layers or structural boards, you clean the surface, measure the run length, cut the tape, peel off the backing, then press it down. The aim is to bond even when the surface isn’t perfectly smooth, creating a more “seam-like” barrier.
Key points
The core appeal here is the butyl adhesive design. Butyl sealants are commonly chosen for their staying power and ability to remain flexible, and this tape is described as weather resistant and able to withstand temperatures from -20°F to 230°F. That temperature range matters if you’re dealing with freeze-thaw swings, hot sun, or cold storage/shipping conditions for outdoor materials.
You also get multiple rolls—12 rolls total—so you’re not forced to buy again halfway through a larger job. The listing notes a total length of 600 feet, and that it can be customized by cutting to the length you need.
Key takeaways for installation
Installation is straightforward, but it’s also where tapes can win or disappoint. The recommended approach is to clean the surface first, then peel, cut, and stick. The tape is described as easy to duct/stretch (the listing language is “duct”), easy to apply, and able to form an instant bond on uneven surfaces like wood and metal.
One limitation to keep in mind: if the surface isn’t clean or properly prepped, adhesion can suffer. Also, tape can’t replace the need for correct flashing/drainage design where water management is critical—think of it as a sealing layer within your overall build.
What it covers (and where it may not)
The product is marketed for waterproofing and protection, and it’s said to work on multiple material surfaces, including wood, metal, plastic, and rubber. That broad “surface coverage” is useful when you’re doing a project like an outdoor repair where you may encounter different components.
But it might not be the best choice if your goal is structural reinforcement or if you need a product specifically designed to handle moving joints, major construction gaps, or complicated flashing systems. Based on the description alone, it’s best treated as a sealing tape for joints/edges where water resistance is the priority.
It also spans a wide temperature range, but if you’re working outside that window—or in conditions where the surface can’t be conditioned for reliable bonding—you may find performance doesn’t match what you’d expect.
Pros
- Waterproof and anti-damage focus for helping protect wooden deck structures
- Self-adhesive design intended to stick quickly after surface cleaning
- Flexible/temperature-resilient positioning (-20°F to 230°F) for outdoor conditions
- 12-roll bundle with 600 feet total length for larger projects
- Intended to bond to uneven surfaces (including wood and metal)
Tech specs
- Name: MOLYLY Butyl Deck Joist Tape
- Type: Deck joist sealing tape (butyl adhesive)
- Size: 1-5/8 in x 50 ft per roll
- Quantity: 12 rolls
- Total length: 600 ft
- Temperature range: -20°F to 230°F
Is it worth it?
Worth considering if you’re building or repairing an outdoor deck, roof framing area, beams, RV-related construction, or a shed where you want an extra moisture barrier. It makes sense if you can do basic prep (clean surfaces, cut to length, press firmly) and you want a tape-style solution that stays flexible for weather exposure.
It may not be a great match if you’re expecting tape to solve a deeper drainage/installation issue, or if your surfaces can’t be cleaned and conditioned for reliable adhesion. Also skip it if you need a specialized flashing or system-rated component rather than a sealing strip.
If your plan is a straightforward joist/edge sealing step, this is the kind of product you buy to reduce future headaches—just don’t treat it like a substitute for correct building practices.
Mini FAQ
How do you install butyl joist tape?
Clean the surface, peel the tape, cut it to the needed length, and stick it down. The listing emphasizes bonding to uneven surfaces once applied.
Is it meant for outdoor use?
Yes. It’s described as weather resistant and rated for temperatures from -20°F to 230°F.
What surfaces can it seal?
The description says it can be applied to wood, metal, plastic, and rubber.
How much tape do you get?
You get 12 rolls for a total of 600 feet, with the ability to cut to your project length.
Can it handle uneven surfaces?
According to the listing, it’s designed to bond to uneven surfaces like wood and metal to help form a seamless seal.