Installing Composite Joists: The Perfect Solution For Low-Lying Decking Projects
NeoTimber composite joists are designed to be installed directly onto a solid concrete base. This low-load bearing subframe option is made from a similar material as our composite deck boards and is a moisture resistant, long-life alternative to timber joists.
Learn How To Install Composite Joists
Key Tips
While other subframe materials are available to installers, NeoTimber’s composite joists are purpose built to work with our decking boards. This solution is excellent for installing a low-lying decking subframe that sits directly onto a solid, flat base.
While the installing composite joists video outlines each step in detail, we thought we would outline the key tips below:
- Incorporate a decline of 1% to your base in order to aid with drainage.
- Lay your joists at right angles to the direction of your boards.
- Install your composite joists at 250-350mm spacings.
- Leave an 8mm gap where joists meet at joins.
- Double-joist the areas you expect deck boards to meet at joins.
- Attach the joists to your concrete base using a 60mm screw; pre-drill and countersink the material to avoid cracking.
- When attaching the composite joist to the concrete base, be sure to begin screwing at least 70mm in from the joist edge.
- Be sure to also leave an 8mm gap from the joist to any solid surfaces, such as a brick wall.
1. Begin With The Base
Your concrete base should have a minimum thickness of 60mm and have a slight decline to allow for drainage. You may also wish to add drainage holes to the base where we recommend an 80mm hole every 4 square metres (4m2).
2. Laying Your Joist Network
Begin installing composite joists by laying your joists directly onto your concrete base. The spacings (or centres) of your joists should be 250-350mm, and they should ideally run at right angles to the direction of your deck boards. Ensure that your joists are orientated with the guidance channel facing upwards before attaching them to the concrete base (this will assist with screwing and water drainage). A gap of approximately 8mm should be left between joins in joists, allowing for expansion. Double joisting is required where you expect deck boards to meet at butt-joins.
3. Attach The Joists To Your Concrete Base
Begin attaching the subframe by pre-drilling through the joist and into your concrete base. Your first fixing should be approximately 70mm from the edge of the joist. Continue to attach the joist at 500-600mm intervals using a 60mm screw.
Installing Composite Joists
Ensure a strong and durable foundation for your NeoTimber® deck by mastering the process of installing composite joists. Follow our practical tips to achieve a level, long-lasting subframe and enjoy a beautifully stable deck for years to come.
