Frame and substructure for composite decking

What base do I need for composite decking? Your guide to composite decking frames

A good quality, solid decking base is critical to ensuring your composite decking looks great and is safe and structurally-sound for many years to come. However choosing the right composite decking frame often gets overlooked!

In this blog we’ll explore the various materials from which your subframe can be constructed and the importance of a correctly installed structure.

What makes up a composite decking frame?

A traditional, basic composite decking frame is made up of decking joists to create the outer frame and bearers and noggins to add strength and support. These are installed in a parallel matrix using posts to connect them and create the composite decking subframe.

The length, width and height of your frame will be determined by the size and shape of your decked area. The spacing between joists, bearers and posts will be determined in the installation instructions of your deck boards and will vary from manufacturer to manufacturer.

Composite decking subframe

What material should I use to build my composite decking base?

The subframe of your composite decking can be made from a number of different materials. The most common are timber, composite wood or aluminium.

The material you choose will be dependent on:

  • The location of your decking
  • The height of your decking
  • The decking load
  • Your budget

Here’s a quick overview of each material and their pros and cons:


The most common type of decking frame is a timber frame. Whilst strong and relatively long lasting, wood requires regular treatments to protect it against the elements and prevent ongoing deterioration. Over time, timber will rot, splinter, and split, which can be detrimental to the safety of the frame. If using a timber frame it’s advisable to get it pre-treated to help prevent weakening of the material.

Rotted timber frame being removed


Composite deck frames are fast becoming one of the most popular choices for decking bases. As with composite deck boards, composite joists and posts require no protective treatments or paints. They will not rot, split, or splinter and are extremely durable, providing you with an extremely long lasting subframe.

Decking subframe in a garden


Aluminium subframes offer a viable alternative to traditional timber. Some aluminium joists and posts will also be fire rated, making them ideal for use in high rise buildings. Whilst the most expensive option, they are light-weight and extremely long-lasting.

Composite decking pedestals

If installing your decking onto concrete, a patio or a roof terrace, composite decking pedestals are an ideal alternative to using posts. It’s also possible to get height adjustable pedestals, making installation much quicker.

How Ecodek can help with your composite decking needs?

Here at Ecodek we are composite decking experts. From base to surface, our experts can help you build the best deck for you and your home. Call our friendly, knowledgeable team today on 01978 667 840 or email for a no obligation chat.

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