Joist Spacing and Span for WPC Decking

in WPC Decking Tips 2021-08-07

When installing WPC decking, many people may feel confused about the spacing of joists. If the span is too large, it will affect the weight distribution, causing insufficient floor support, and the boards may bounce and easy to sag. If the span is too small, it will be difficult to install the boards. Therefore, spacing between joists is very important for floor installation. In the following, we will introduce the appropriate joist spacing of WPC decking to help you avoid some common installation errors.

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What is a decking joist?

Joists play a major role in installing the floor firmly and safely as the boards are fixed on the joist frames. Joists are used to connect and support the entire floor and they can also help the floor drain and ventilate. We use aluminum alloy joists, which are stronger than wood and will not rot and warp over time. It is the perfect solution for the outdoor decking joist system.

Joist Spacing & Span

We usually recommend the joist span between 300~450mm (12 ~18 inches), but it could be different for the profiles of different sizes. In addition, commercial applications and residential applications have different requirements for joist span. For safety precautions, commercial applications usually require smaller spacing. You could refer to the below guideline of joist installation span for Techwoodn’s conventional WPC Decking models:

Item CodeJoist Spacing in PrivateJoist Spacing in Commercial
TW21-145H1350 mm300 mm
TW23-146H1400 mm350 mm
TW25-135H2350 mm300 mm
TW25-140H3400 mm350 mm
TW25-150H4400 mm350 mm
TW30-145H1400 mm400 mm
TW19-135F1350 mm300 mm
TW21-145F3350 mm300 mm
TW23-146F2450 mm400 mm
TW25-135F2450 mm400 mm
TW25-140F3450 mm400 mm
TW20-145F1500 mm450 mm

Finally, before installing the joists, it is necessary to check that the frame must be firmly fixed and to ensure the joists are as horizontal as possible, otherwise, the floor surface will be uneven. If you have any questions about the installation, welcome to contact us for more information.