Decking Joists

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C16 Timber Joists UC3u Treated Kiln Dried Regularised FSC 44 x 95mm (4x2)

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£4.09 - £23.49 per piece (Ex VAT)

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£4.91 - £28.19 per piece (Inc VAT)

Our planed & regularised treated sawn timber is perfect for structural timber carcassing as it comes in��C24 grade. This timber is ideal for a number of uses in the home and garden. The pressure treatment on this timber protects it...

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£4.09 - £23.49 per piece (Ex VAT)

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£4.91 - £28.19 per piece (Inc VAT)
Rough Sawn Timber UC3u Treated Kiln Dried Regularised FSC 44 x 44mm (2x2)

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£2.04 - £11.75 per piece (Ex VAT)

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£2.45 - £14.10 per piece (Inc VAT)

Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers. Carcassing is a...

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£2.04 - £11.75 per piece (Ex VAT)

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£2.45 - £14.10 per piece (Inc VAT)
Timber Floor Joist UC3u Treated C16 FSC 44 x 145mm (6x2)

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£6.13 - £35.23 per piece (Ex VAT)

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£7.36 - £42.28 per piece (Inc VAT)

Our treated timber floor joists are designed for external use, making them ideal for wet areas or direct ground contact. Common applications include timber decking joists, shed bases, posts, and sleepers. Available in various timber joist dimensions,...

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£6.13 - £35.23 per piece (Ex VAT)

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£7.36 - £42.28 per piece (Inc VAT)
C16 Timber Joists UC3u Treated Kiln Dried Regularised FSC 47 x 75mm (3x2)

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£3.25 - £18.67 per piece (Ex VAT)

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£3.90 - £22.40 per piece (Inc VAT)

Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers. Regularised timber has...

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£3.25 - £18.67 per piece (Ex VAT)

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£3.90 - £22.40 per piece (Inc VAT)
C24 Timber Joists UC4 Treated Redwood 47 x 100 x 3600mm (4x2)

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£18.73 each (Inc VAT)

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£15.61 each (Ex VAT)

Crafted for durability and strength, our C24 Timber Joists UC4 Treated Redwood 47x100x3600mm are the ideal choice for your outdoor decking projects. These joists are UC4 treated, ensuring they are well-suited for ground and water contact, making them...

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£18.73 each (Inc VAT)

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£15.61 each (Ex VAT)
C24 Timber Joists UC4 Treated Redwood 47 x 150 x 3600mm (6x2)

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£28.09 each (Inc VAT)

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£23.41 each (Ex VAT)

C24 deck joists are perfect for supporting your decked area. This timber is UC4 treated, meaning that not only is it ideal for outdoor use, but it is also suitable for direct contact with the ground. C24 graded timber is a premium loadbearing grade...

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£28.09 each (Inc VAT)

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£23.41 each (Ex VAT)
C24 Timber Joists UC4 Treated Redwood 47 x 100 x 4800mm (4x1)

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£21.07 each (Inc VAT)

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£17.56 each (Ex VAT)

C24 deck joists are perfect for supporting your decked area. This timber is UC4 treated, meaning that not only is it ideal for outdoor use, but it is also suitable for direct contact with the ground. C24 graded timber is a premium loadbearing grade...

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£21.07 each (Inc VAT)

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£17.56 each (Ex VAT)
C24 Timber Joists UC4 Treated Redwood 47 x 150 x 4800mm (6x2)

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£37.46 each (Inc VAT)

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£31.22 each (Ex VAT)

Add the long lasting UC4 C24 Timber Joists to your garden, expertly designed for durability and strength. Ideal for constructing robust decking structures, these joists are UC4 treated, ensuring they withstand direct ground contact and resist moisture,...

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£37.46 each (Inc VAT)

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£31.22 each (Ex VAT)
ArborJoist Recycled Plastic Sub-Frame Decking Joists 3000 x 50 x 50mm

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£18.65 each (Inc VAT)

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£15.54 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,...

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£18.65 each (Inc VAT)

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£15.54 each (Ex VAT)
C16 Timber Joists UC3u Treated Kiln Dried Regularised FSC 44 x 120mm (5x2)

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£5.11 - £29.36 per piece (Ex VAT)

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£6.13 - £35.23 per piece (Inc VAT)

Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers. Regularised timber has...

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£5.11 - £29.36 per piece (Ex VAT)

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£6.13 - £35.23 per piece (Inc VAT)
C16 Timber Joists UC3u Treated Kiln Dried Regularised FSC 44 x 195mm (8x2)

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£8.17 - £46.98 per piece (Ex VAT)

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£9.80 - £56.38 per piece (Inc VAT)

Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers. Regularised timber has...

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£8.17 - £46.98 per piece (Ex VAT)

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£9.80 - £56.38 per piece (Inc VAT)
C16 Timber Joists UC3u Treated Kiln Dried Regularised FSC 44 x 220mm (9x2)

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£9.19 - £52.85 per piece (Ex VAT)

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£11.03 - £63.42 per piece (Inc VAT)

Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers. Regularised timber has...

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£9.19 - £52.85 per piece (Ex VAT)

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£11.03 - £63.42 per piece (Inc VAT)
C16 Timber Joists UC3u Treated Kiln Dried Regularised FSC 44 x 170mm (7x2)

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£7.15 - £41.11 per piece (Ex VAT)

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£8.58 - £49.33 per piece (Inc VAT)

Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers. Regularised timber has...

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£7.15 - £41.11 per piece (Ex VAT)

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£8.58 - £49.33 per piece (Inc VAT)
ArborJoist Recycled Plastic Sub-Frame Decking Joists 3000 x 125 x 50mm

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£62.68 each (Inc VAT)

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£52.23 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,...

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£62.68 each (Inc VAT)

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£52.23 each (Ex VAT)
C16 Timber Joists UC3u Treated Kiln Dried Regularised FSC 72 x 97mm (4x3)

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£6.52 - £37.48 per piece (Ex VAT)

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£7.82 - £44.98 per piece (Inc VAT)

Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers. Regularised timber has...

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£6.52 - £37.48 per piece (Ex VAT)

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£7.82 - £44.98 per piece (Inc VAT)
C16 Timber Joists UC3u Treated Kiln Dried Regularised FSC 72 x 145mm (6x3)

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£9.78 - £56.23 per piece (Ex VAT)

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£11.74 - £67.48 per piece (Inc VAT)

Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers. Regularised timber has...

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£9.78 - £56.23 per piece (Ex VAT)

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£11.74 - £67.48 per piece (Inc VAT)
C16 Timber Joists UC3u Treated Kiln Dried Regularised FSC 72 x 170mm (7x3)

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£11.41 - £65.60 per piece (Ex VAT)

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£13.69 - £78.72 per piece (Inc VAT)

Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers. Regularised timber has...

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£11.41 - £65.60 per piece (Ex VAT)

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£13.69 - £78.72 per piece (Inc VAT)
C16 Timber Joists UC3u Treated Kiln Dried Regularised FSC 72 x 195mm (8x3)

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£13.04 - £74.97 per piece (Ex VAT)

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£15.65 - £89.96 per piece (Inc VAT)

Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers. Regularised timber has...

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£13.04 - £74.97 per piece (Ex VAT)

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£15.65 - £89.96 per piece (Inc VAT)
C16 Timber Joists UC3u Treated Kiln Dried Regularised FSC 72 x 220mm (9x3)

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£14.67 - £84.34 per piece (Ex VAT)

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£17.60 - £101.21 per piece (Inc VAT)

Treated timber is suitable to be used externally and is suitable for wet areas or areas where the timber will be coming into contact with the ground. Examples of treated timber uses are outdoor decking, shed bases, posts, sleepers. Regularised timber has...

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£14.67 - £84.34 per piece (Ex VAT)

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£17.60 - £101.21 per piece (Inc VAT)

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!

How to guides

How to build a deck

How to build a decking using our timber products.

Find out more

How to build a raised deck

A step by step guide on how to build your own raised decking area.

Find out more