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How to Install Composite Decking: Step by Step

6 February 2024


When it comes to installing your composite decking, you might choose to go with a professional tradesperson, or try and keep down costs by doing it yourself. Whichever you decide, it’s important to follow the manufacturer's guidelines so it looks great and lasts for many years to come. 

In this guide, we provide an overview of how to lay composite decking and advise you on the right tools and accessories for the job. 

If you’ve purchased composite decking from Eurocell, we also recommend downloading and referring to our Composite Decking Installation Guide

Storage and handling 

When your composite decking boards arrive, you should take extra care to prevent any damage before they’re installed. 

Clear a space to store them, and bear in mind the following do’s and don’ts.


  • Keep them in the shade
  • Keep them clean
  • Store them indoors
  • When storing, keep them 500mm above the ground
  • Get someone to help you move, lift and handle them
  • Keep them clear of dust or debris
  • Acclimatise two days prior to installation
  • Prepare a suitable substructure
  • Dispose of old decking responsibly – either at a recycling centre or skip


  • Get them wet
  • Stack them higher than 3m per stack
  • Slide them over each other 
  • Cover with plastic sheeting
  • Install composite decking onto old decking
  • Burn old treated decking as it can release toxins into the environment 

Tip: Hold the boards from the middle or on their edge when carrying, so that you can fully support it.

Stay safe 

Before starting the installation, it’s vital that you take safety precautions. When cutting and installing the boards, make sure you wear personal protective equipment (PPE) like gloves, goggles, a dust mask, and you cover exposed arms or legs.

When installing the decking, you should have at least 25mm clearance between the boards for adequate water draining, air circulation and to make the installation easier. It’s also necessary to install them on a secure substructure (ideally at <400mm centres) so that load can be spread evenly when walking on the deck, and to prevent moisture damage.  

Tools you’ll need to install composite decking

The following tools will help you with a quality installation: 

  • Circular saw with a 60T aluminium or laminate multipurpose blade
  • Mitre saw
  • Jig saw
  • Hand drill
  • 3mm and countersink drill bits
  • Tape measure
  • Set square
  • String line
  • Spirit level
  • PPE
  • Pencil

Now that you’ve got all you need, let’s get started. 

How to Install Composite Decking: Step by Step

Step 1: Installing your substructure 

First, make sure you have a secure frame or substructure. The joists should be fixed to a secure post with adequate spacing (typically less than 400mm), and should be in at least three places. This ensures that you have even load distribution and more points of support.

Step 2: Get the layout right 

We recommend that you lay the boards perpendicular (where two surfaces meet at a 90 degree angle) to the direction of the sub-frame, building line, door or view point. Not only does it look great with this technique, but it’s more stable and prevents issues like warping.

Step 3: Fix the starter clips 

Once you have decided where your first board will be laid, you should align the starter clip to the end and centre of the joist. Next, pre-drill a hole and then secure the clip into place. You can now install the rest of the starter clips, using a string line for more precision. 

Note: Make sure that the fixings are fastened at a 90 degree angle to the decking system. 

Step 4: Install the first board 

Next, take the decking board and using the grooves (you will see them on the side of the board), slide it into the starter clips. 

Step 5: Install the t-slips

It’s time to install the t-clips, and you can use the hidden ones for a more seamless finish. Starting on one side of the board, slide the t-clip into the groove and then, part-screw the t-clip into the joist. It’s important to not secure them fully at this stage. Using the same steps, install the remaining t-clips into the joists. 

Note: You only need to install one t-clip per joist. 

Step 6: Install the locking clip

Locking clips will secure the board to the substructure. It’s best to install one locking clip where the board hits the subframe, making sure it’s in the centre. 

Step 7: Install your second board

Moving onto your second board, slide it into the t-clips fixings that you installed earlier. Going back to step five, install a new row of t-clips on the second board. 

Step 8: Fasten the t-clips

It’s time to go back to the first board, and fully secure the t-clips that you part-screwed. 

Step 9: Install the rest of the boards 

Following the steps above, you can now install the rest of the decking boards. 

Step 10: Laying boards end-to-end 

If you are laying the boards end-to-end, it’s best to leave a 2-3mm gap between them to help with its natural movement, and to prevent uneven surfaces in the long-term. 

Step 11: Breaker boards 

You may instead choose to install breaker boards to break up the decking area and add variety to the pattern. To do this, you can fasten them with t-clips or starter clips. Simply, cut one side of the t-clip off or install the starter clips in the same way you did earlier. 

Step 12: Installing fascia boards

Fascia boards are great to finish the look because they cover the edges and ends of the decking. To secure them, line up the boards with the top edge of the decking. You can then use colour coded screws to fix it into the joists. 

Step 13: Installing angle trim 

You can also use angle trim to conceal corners and edges. You can cover the exposed areas with leftover decking boards, and then join the angle trim to the top edge of the board using colour coded screws or poly pins. 

While these steps may seem comprehensive, installing composite decking is simple and once you lay the first board, you will get the hang of it pretty quickly. As always, it’s important to follow your manufacturer's guidelines to the detail, so that you don’t impact your warranty and you get the best possible finish.


Read Next

Browse Eurocell composite decking online here.

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