What is decking joist tape?

What is decking joist tape?

Joist tape is a simple and cost effective way to protect your decking substructure. The tape is easily stuck to the top of any joist and beams facing up. Once applied the chosen decking material is fixed over the top. This ultimately stops the opportunity for any water or moisture to sit on the top and penetrate into the treated timber.

I use treated joists; do I still need joist tape?

Any professional decking installer knows using Class IV treated pine is standard for decking substructures. This treated timber will last in the ground approximately 15-20 years depending on the environmental factors. Choosing to invest in a premium decking material that carries a warranty of 25 years+. This warranty won’t cover your substructure so if that rots then you will need to start again. It is certainly worth the little extra in cost and time to apply the tape because you will get a much better return on your investment.

What is decking joist tape?

Why not use HDPE plastic joists instead of Joist tape?

Of course, timber isn’t the only material that can be used for decking substructures. However, timber is and will always be the most cost effective and quickest way to build a substructure.

Yes, plastic last forever but plastic costs add up very quickly to the point where you’re easily spending double. When using a high-quality decking brand – fitted by an approved installer – this will often carry a big warranty of 25 years plus. Let’s assume everything lasts 25 years. By then would you want to change it for something new or will you have already moved?

What’s the best decking joist tape?

There are range of brands available that all vary in cost and quality. You’ll see these tapes are made from either Butyl or Asphalt. Look for Butyl if you can. Butyl tape is easier to apply because it sticks better in different temperatures. Also, Butyl tape creates a far better seal around screws so offers better protection against moisture.

Trex are the number 1 decking manufacturer worldwide. They have an extensive collection of approved TrexPro installers and all of them must use their TrexProtect tape on every single one of their installations.  It’s strict guidelines like these that mean they put a 25 year warranty on every deck built by their pro’s

Cutting the tape and using liquid sealants instead?

There are many contractors that assume that a liquid product is the war forward and will try anything to circumvent the cost of decking tape. The idea of decking tape is two fold. The primary objective is to prevent rain water from penetrating into the upper surface of the joist. The second is to prevent water from penetrating into the joist via the screw hole. The tape prevents water from entering the same hole as the screw by self sealing around the screw during installation.

If you use a bitumastic paint or sealant you will take far too long and the labour is costly. You have to wait for the product to dry fully before further works can take place. The liquid product is not designed for this application. The product may breakdown over time. The product doesn’t self seal once the screw has penetrated through it… Plenty of reasons why it not the right move as a professional.


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