How to prepare before installing composite decking

Whether you’re installing composite fencing or decking, there are a couple of things to do before you officially get started. First, read through this guide and ensure that you have all the tools, materials, and other equipment required in easy reach.

Second, make sure that you acclimatise the composite boards before installing them, as this will help stop the boards from unwanted shrinkage. An easy way to acclimatise your boards is by laying them on a ground sheet and keeping them covered for between 48 and 72 hours.

What tools and materials are needed for fitting composite decking?

By ensuring that you have all the tools and materials required for fitting composite decking in easy reach, you can look forward to a smoother installation. In addition to the composite fence panels and posts or composite decking boards and joists, starter/finish clips, hidden T-clips with screws, locking clips with screws, angle fascia trim, flat decking trim, and additional screws, you’ll also need a few standard woodworking tools. We recommend using the following:

Circular saw with a 60T+ aluminium/laminate multipurpose blade

Jig saw

Mitre saw

Hand drill with 3mm and countersink drill bits

Set square

Tape measure

Spirit level

Stringline

Protective eyewear and other personal protection equipment (PPE)

Pencil

How to install composite decking?

We're now ready to find out how to install composite decking:

Step 1: Install substructure timber joists

Use A4 stainless steel countersunk wood/masonry screws to attach joists to the substructure.
Fix the joists at 400mm centres.
Each joist must be fixed in at least three places.

Step 2: Orient the decking boards

Decide which direction to lay the composite decking boards in.
Boards look and function best when laid perpendicular to the sub-frame and building line, door, and viewing point.
Ask our team about other layout options.

Step 3: Fix the starter clips after determining the first board’s location and orientation

Align the starter clip with the centre and end of the joist.
Pre-drill holes.
Use the starter clip screw to screw the clip into place.
Use a string line or decking board to help you install the rest of the starter clips.

Step 4: Install the first decking board

Slide the first composite decking board into the starter clip.
Use the grooves on the side of the board to do this.
Make sure the board is installed into the clip completely.

Step 5: Install the T-clips

Slide a hidden T-clip into the decking board’s side groove.
Partly screw the T-clip screw into the joist to secure one end of the board.
Follow the same steps to install the remaining T-clips.
Install one T-clip per joist.

Step 6: Install the locking clip, if using

You can install locking clips to ensure the decking boards expand and contract evenly.
Install locking clips where the centre of each board meets the sub-frame.

Step 7: Install the second composite decking board

Slide the second decking board into the T-clip fixings.
Install the second row of T-clips to the second board as described in step 5.

Step 8: Secure the first set of T-clips

Secure the first set of T-clips when the second board is in place.
Use a suitably wide screw bit to avoid damaging the boards.
Ensure the drill chuck doesn’t touch the boards to prevent damage.

Step 9: Install the remaining decking boards

Repeat steps 5 through 8 to install the remaining composite decking boards.
If boards require end joints, plan where you want those joints to be visible.
Make any joints over a double joist. Make any joints over a double joist.

Step 10: Finish the deck – two options:

Option 1: Fascia Board

Attach fascia trim to create a clean edge after installing the main boards.
Align the first trim with the decking’s top edge.
Use colour-coded screws to fix the trim into the joists – use two screws per joist every 400mm.
Pre-drill and countersink the screws for a good finish and to prevent cracking.

Option 2: Angle Trim

Use additional decking boards to clad the decked area’s face.
Install the boards in a similar manner to decking – you can use countersunk screws instead of T-clips.
Pin the angle trim to the decking’s top edge using colour-coded screws – use one screw per joist every 400mm.
Pre-drill and countersink the screws, as above.

Tips for composite decking maintenance

While composite fencing and decking from BM Steel is made to provide robust service for years to come, you will need to do maintenance once or twice a year to remove accumulated dirt and debris. Here are three composite decking maintenance tips:

Clean your decking or fencing by using a scrubbing brush to scrub it with all-purpose cleaner and water.

Use a high-pressure cleaner with a fan-shaped beam held at least 20cm from the surface to wash the decking or fencing in a lengthwise direction.

Gently rub the decking lengthways with coarse sandpaper (80gsm or similar) to remove burn marks from barbecues, etc.

Choose composite decking that lasts

As you can see from our guide on how to fit composite decking, the process requires careful planning, a few tools and materials, and some PPE. The time and effort spent preparing for and installing your decking will be well worth it, however, as your home’s new feature will add value in more ways than one. In addition to being a desirable feature, your deck is sure to be your family's and friends' new favourite spot. Choose the UK’s best composite fencing and decking. Choose BM Steel.

How to Fit Composite Decking