Decking Joists

Decking joists are an integral part of the structure of your decking. C16 and C24 structural graded, treated decking joists are perfect for a decking project that is designed to last.

Filter Results

Shop by

No filters applied

Apply Filters

Check local branch stock

Special Offer

Special Offer

ArborJoist Recycled Plastic Sub-Frame Decking Joists 3000 x 50 x 50mm

WAS: each

WAS £18.65

£15.30 each (Inc VAT)

WAS: each

WAS £15.54

£12.75 each (Ex VAT)

The ArborJoist Recycled Plastic Sub-Frame system provides a high quality, high performance substructure, and a long-lasting and durable alternative to timber. As it is made from solid recycled plastic it means that is rot resistant and weather resistant,...

WAS: each

WAS £18.65

£15.30 each (Inc VAT)

WAS: each

WAS £15.54

£12.75 each (Ex VAT)
Special Offer

Special Offer

ArborJoist Recycled Plastic Sub-Frame Decking Joists 3000 x 125 x 50mm

WAS: each

WAS £62.68

£47.94 each (Inc VAT)

WAS: each

WAS £52.23

£39.95 each (Ex VAT)

The ArborJoist Recycled Plastic Sub-Frame system provides a high quality, high performance substructure, and a long-lasting and durable alternative to timber. As it is made from solid recycled plastic it means that is rot resistant and weather resistant,...

WAS: each

WAS £62.68

£47.94 each (Inc VAT)

WAS: each

WAS £52.23

£39.95 each (Ex VAT)

Decking Joists

When choosing the right decking joists for your project, the size you need will depend on the overall dimensions of your deck. We offer a variety of decking and joists in different lengths, all available for delivery from any of our branches. For timber decking, a good rule of thumb for decking joist spacing is 450mm centres (or 400mm if using a chevron pattern). For composite decking joists, spacing should be 400mm centres, or 300mm when opting for a chevron pattern.

Additionally, consider using deck joist tape to protect the joists from moisture, and joist hangers for decking to ensure a secure and durable installation.

Frequently Asked Questions

What size deck joists?

The deck joist size required depends on your project design. Our most popular sizes are 47x100mm, 47x125mm, and 47x150mm. These are available from every Howarth branch in lengths of 3m, 3.6m, 4.2m, and 4.78m. We also have availability of 5.4m and 6m at select branches

What size screws for decking joists?

Camo deck screws are perfect for fastening deck boards to joists. For the framing, structural wood screws will do a great job.

How far apart should deck joists be?

When designing how far apart your deck joists should be, a good timber decking spacing is 450mm centres (or 400mm centres is using a chevron pattern), and 400mm centres for composite decking (or 300mm centres if using a chevron pattern).

How many decking joists do I need?

The number of decking joists needed is dependant upon the size of the decking project. It can be calculated based on spacing of 450mm centres for timber decking (400mm centres for chevron pattern) and 400mm centres for composite decking (300mm centres for chevron pattern).

What wood to use for deck joists?

C16 or C24 timber is ideal for decking joists. It is structural graded and when well put together will keep the decking strong and stable.

How thick should decking joists be?

Decking joists are most commonly 47mm in size.

Should I stain deck joists?

We always recommend treating timber and maintaining it over time, this includes decking joists. This will increase the longevity of the decking structure. Don’t forget to protect the ends!