A Guide On How To Plan Your Composite Decking Project

A deck basically provides outdoor living space, which is either freestanding or attached straight to your home and can be used for a multitude of purposes. Whether you are looking to create a play area for your kids or even out a slope in your garden to create a space for relaxation and hosting friends in summer – the options are sheer endless.

Luckily, planning and building a deck is no rocket science, especially when using composite as your main material, and can therefore be a job done easily by yourself; as long as you have the correct tools and the skills to use them, and perhaps a helping hand or two in the process, you are basically able to man this whole project alone!

Are you ready for some mid-summer nights spent in your beautiful, new outdoor space? To support you with your composite decking endeavour, we have put together this easy guide on how to plan your composite decking project successfully.


What are you using your deck for?

Are you aiming to build your deck to be an entertainment and social area in your garden, an area for your children to play while getting some fresh air without getting dirty from the muddy ground, or are you looking to build a space to relax outdoors, potentially with a hot tub or even a pool?

Having the use of your deck figured out is quite an important step when it comes to planning a project like this. Since the utilisation of your deck will determine not just the type of deck boards needed but also the location of your new building project in your garden, you should make up your mind on this question first.

Here are some further ideas for different functions of a deck:

  • BBQ area
  • Stargazing area
  • Complementing the paving or turf
  • Neatening up the slope in your garden


Luckily, composite is an incredibly versatile material, meaning no matter which purpose your deck is going to fulfil, your composite decking is not going to disappoint. It is easy to install and comes with very few maintenance requirements. On top of this, the composite is all-weather resistant and comes with valuable anti-slip features.


Where are you going to place your deck?

The location of your deck is obviously tightly linked to the function of your deck. This is why there are some further options on where you can place your deck, which can also influence what you are going to use it for:


Rooftop Deck

When planning a rooftop deck, going for composite decking is definitely advisable. Thanks to its durability, due to it being made out of recycled plastic and wood, it will come with way less maintenance and remain UV stable for much longer than traditional timber decking.

As you look into the construction side of a rooftop deck, make sure you go with composite decking that is built on a sub-frame instead of having to penetrate the roof or house walls, which can cause significant damage or, even worse – the insulation to break and water to come into your house.

When going for a rooftop deck, consider that this part of your house might be exposed to the most sunlight, i.e. UV. Our Forma composite decking has a 25-year warranty and is UV bleaching resistant, which will aid in keeping your deck as colourful as new. We also offer a full maintenance free substructure in the form of solid plastic or aluminium joists as well as various decking pedestals.


Garden Deck

Using composite decking for a multi-functional garden deck, to host BBQs, have your children play or even place a hot tub on is amazing, as it doesn’t require much treatment and comes with a handy anti-slip feature.

No matter whether your garden deck will just be hosting garden furniture, or standing underneath a tree or in the sun all day long, UV-protected and stain-resistant composite is definitely the way to go.


Balcony Deck

Whether your balcony deck is for commercial or domestic purposes, choose materials which have high UV stability, an anti-slip feature and do not wear and tear quickly. As an eco-friendly alternative to timber decking, considering composite for your balconies can be a smart choice to make.

On top of that, make sure to plan whether you will require drainage systems or other extras for heavy weather on your balcony deck!


Commercial Deck

No matter if it is for outside seating space for your restaurant or pub, a business roof-top terrace or smoking area for your employees or evening out the ground for some hotel guests – if you are in need of a deck that can host large crowds and lots of change of feet, or better shoes, then going with composite decking will be your best bet, as well.

The hard-wearing material with anti-slip features will keep everybody safe, and your deck will look its best for a long time to come!


Things to consider

Here are some of the general variables to consider, no matter how you are going to use your deck or even where you are going to be building it on your property:

  • Will your deck be built on level or sloping ground?
  • Is the deck going to join up to your house, or will it be placed further away from it, perhaps under a tree in your garden?
  • Will your deck get much sun, or are you building it in a shaded space?
  • How much privacy will your deck have, and does it potentially need a bit of fencing around certain sides?
  • Are there any other features you might have to work around, such as trees, boulders or posts?
  • If there are any features, especially trees, what trees are they and how fast do they grow (meaning you might have to leave them more room in your deck to expand), do they lose their leaves in winter or give off a lot of blossoms in spring which might make the deck harder to clean?
  • When building a ground-level deck, is the ground wet or rather dry underneath? The soggy ground might make the deck unstable.


Before definitely choosing a site to build your deck, we suggest renting a CAT (cable avoidance tool) as well so that you can check whether you have any cables or even pipes on your property which might end up lying underneath your decking area.

This is important, as in the worst case, you might have to demolish your deck in order to reach those cables or pipes if there happens to be an issue, rather stay clear of any areas that have any of these items in the ground to keep your deck for as long as possible!

If you are still unsure about where to place your deck and what it should look like, check out this composite decking inspiration with beautiful and versatile decks from across the globe! Then get yourself a plan of your house and the garden and mark where you want to start your deck project!


How big is your deck going to be?

How much of your outdoor space do you want to cover with your deck? What is the size of your garden? How big can a rooftop deck be? Is your new balcony going to be only on one side of the house or go around the house wall? Those are some important questions to consider when trying to figure out the size of your future deck space.

Figuring this out will also give you insights on how many deck boards you will have to use – but we will touch on this a bit later.

One expert piece of advice, no matter the space for your deck project plans – be conservative with your size, as you can always extend (most decks) later as well.

Below are steps which will assist you in figuring out the size, structure and design of your future deck in order to have better knowledge about materials, how many deck boards and deck railings, as well as what decking frame you will have to purchase.


Decking Structure

There are various possibilities when figuring out your decking structure. To keep it simple, here are the most common ones:

  • Basic ground-level deck
    • great for level gardens and ground areas
    • most basic decking structure
    • either with footings or directly on the ground
    • think of extras, such as decking lights & lamps in the corners
  • Ground-level deck with a balustrade (deck railings)
    • used for children and or pets to remain in one area
    • decorative or practical purpose of railings (for pot plants or light rails underneath)
    • potentially needs a gate
  • Elevated deck with deck railings and potential stairs
    • best for gardens with slopes
    • more time- and resource-consuming to built
    • space below the deck can be used for storage or garage purposes
    • consider skirting panels & lighting


Depending on whether your decking structure requires an extra sub-frame, you can go with one of our solid plastic or aluminium sub-frames, which will be arranged on adjustable pedestals, concrete blocks or other solid posts.

These structures will ensure that your deck will not warp or bend and easily spread any weight load across the frames so that your deck lasts for many years.


Decking Design

There are several options on how you can configure your deck boards, which will ultimately have an impact on how your deck will look and feel. Here are some of the most popular design options:

  • Horizontal Deck Boards
  • If you horizontally lay your deck boards, your deck will have a traditional look. When going for the standard right-angled decking, make sure to measure a max of 400mm between the centre of one supporting joist and the next.
  • Diagonal Deck Boards
  • A classic look with a bit of a contemporary twist, diagonally laid boards, require joists that are spaced 300mm from centre to centre in order to have a safe and secure structure.
  • Chevron Deck Boards
  • The chevron pattern is very decorative and might remind some of us of a typical parquet floor. Your joists should be 300mm from centre to centre. On top of this, make sure to lay a double joist at the point where each board meets; otherwise, they will not be fixed properly.
  • Picture Frame Deck Boards
  • If you want to go for a bit more of a non-traditional look and would like your deck to stand out and be more decorative, going with a picture frame pattern might be a good choice. When using boards to create a border to the main design, make sure you support the surface pattern sufficiently in the corners to create a stable deck.


It is important to decide on the pattern before you start building your deck, as the design has a significant impact on the material, specifically on the number of joists as well as the board spacing.


Decking Layout

You can always choose to lay your decking at different levels and heights, which can give a different flair to your garden in no time. On top of that, you should remain an open mind when it comes to the layout of your decking. A curved edge or round decking can provide a soft finish to your garden, while rectangular or square decks bring a more traditional flair.

When it comes to your decking layout, the use of your deck, as well as the existing features in your garden, have a significant influence on the space. If you have some existing garden furniture or other items you would like to place on your deck, arrange them in a way that is to your liking and consider enough space to move these items around – that’s your ideal layout!



Deciding which composite decking materials you should use for your deck depends very much on your personal liking as well as on the future use and position of your deck.

Our composite decking boards come in various colours as well as finishes, which will suit any deck design or requirement. Depending on the function of your future deck, you can either choose our:

  • Clarity Composite Decking
  • With 95% recycled material, this stunning and very low-maintenance alternative is not just extremely eco-friendly but has outstanding anti-slip qualities, making it ideal for commercial or garden decking.
  • You can choose between five different colours as well as go for a reversible finish, and no painting, staining or extra sealing of the materials will be required from your side.
  • Forma Composite Decking
  • If you are in need of a more durable composite decking because you might have children or animals, or perhaps some garden parties and hot tub water being splashed onto your deck from time to time – our Forma range is a reliable dual surface material to go with.
  • A dual side capped decking board with a traditional timber grain on one side and a 25mm groove on the other. These decking boards mimic a natural wooden surface perfectly while providing fewer maintenance needs and an extremely durable outer layer that is slip-resistant, anti-splinter and crack-resistant to protect your loved ones’ feet and paws even better!


On top of the deck boards and depending on which deck structure, design, and use your will be going for, you will have to decide whether you require a sub-decking frame or normal decking frame and pedestals, starter clips, and T-clips, as well as other fixings and fixtures.


Amount of Deck Boards needed

Now that we have covered the size, design and functionality aspects of your decking project, it is important to calculate how many deck boards you are going to need. If you are unsure, you can always contact one of our specialists, who will be happy to assist you with calculating the correct number, but here’s an easy way to calculate it yourself:

First of all, and to recap, the following is required:

  • The material your future deck will be made of
  • The exact size of your deck area
  • The width and length of your deck boards
  • Allow for about 10% of wastage (which is standard)
  • Allow for a slight fall on your composite decking so rain water can easily drain away, this prevents puddling.
  • Don’t forget to include the required expansion gap between the length of the deck boards AND at the ends of these deck boards
    • The deck boards require expansion gaps between each other in order to let any water (rain, pool, plant or hot tub induced) flow in between the decking boards to avoid any puddles. On top of that, as the name already suggests, expansion gaps are also used to allow for the deck to contract and expand due to different weather influences and temperature changes.
  • Composite decking boards require:


Decking Equation:


  1. Multiply the width of your decking area with the length to calculate the surface area of your deck (DSA) in square metres.
  2. If you choose our Clarity of Forma decking boards then you will need 2.15 x 3000mm boards per m2 or 1.35 x 4800mm per m2.
  3. The calculation for the Clarity and Forma range is the same as the deck board is 150mm in width.
  4. The calculation for the Grande composite decking boards is 1.20 x 3600mm = 1m2. As the board is 225mm in width.
  5. The above calculation includes 5mm for the t-clip. Please allow a minimum of 5% for wastage. When wanting to keep to full boards or laying the decking boards diagonally be prepared to allow for even more wastage.
  6. We recommend that once you have your calculations ready, you should contact one of our support staff to ensure that you are on the right track. Sometimes it is also advisable to order a handful of boards for your composite deck extra in case you damage one while busy constructing your deck or screw holes on the wrong sides etc.


Decking Accessories

Just because you have calculated the amount boards required for your composite deck project, you mustn’t forget about edging and trims! If you want your deck to look as though it was done by professional installers, make sure to add a trim to the exposed edges of your deck as well as an appropriate ending which gives the whole thing a clean finish.

On top of that, considering whether you need to order additional lamps, rails or gates should also be part of your decking project.

We provide trims, edges, rails and gates in the same beautiful composite materials as your deck boards, which you can mix and match to make your deck stand out even more.


Are there any building regulations to consider?

Before you go ahead with your composite deck project, make sure that you have checked whether there are any building regulations or local bye-laws that require permission from your local building council.

To be 100% on the safe side, we recommend contacting your local planning authority and consulting them about whether or not there will be any building regulations or restrictions imposed on your design.

Checking in with your neighbours might also be a good idea, as often, when it comes to getting planning permission, neighbours’ support or objections can have a big effect on your planning permission.

As a general rule, however, you will not have to worry about seeking planning permission if your deck:

  • is no more than 30cm above ground
  • is not built on a listed or conservation property
  • covers less than half (50%) of your property’s outdoor space.

For more information on this, the UK’s planning portal will be a useful resource.



Here is some more useful background information on composite materials and what makes them different to your traditional wood decking boards.


What is composite decking made of?

Composite is usually made from a mix of reclaimed wood fibres and plastic composites. Thanks to this specific combination and the way our composite is treated, it has special features such as non-slipping, -cracking and warping, which will make it very low maintenance.

All our composite deck boards are made from 95% recycled materials (high-density polyethene plastic), and our wood for the reclaimed wood fibres is FSC certified, which makes our composite extremely eco-friendly.


Why choose composite decking boards?

Our composite decking has various advantages over using traditional wood decking, such as:

  • more longevity & durability
  • low maintenance
  • eco-friendly
  • BS 7976-2:2002 certified
  • FSC certified wood only
  • non-slip feature
  • rot resistant
  • warp & splinter free
  • UV grantees – Forma and Grande range
  • 20 – 25 year warranty, depending on which deck board material you choose


Is composite decking more eco-friendly than traditional timber decking?


All our materials are made of 95% recycled and FSC-certified wood and therefore offer a way more eco-friendly and sustainable alternative to wood decking. On top of that, the most common reason why a deck has to be redone is that the wood used for the deck boards has started to rot or the sun has caused significant UV damage.

This does not happen to our long-lasting composite deck boards. And in this case, durability automatically translates into sustainability!


Final Thoughts

Now that you have your ultimate guide on how to plan your next deck project, choose from our composite decking boards variety to turn your outdoor space into the perfect haven of tranquillity or outdoor event space for your next neighbourhood barbeque!

Gary is the founder and CEO of Ecoscape UK. Gary graduated from Liverpool JM University in 2007 with a 2:1 in Economics. A passion for innovation, design and sustainability, Gary has put to market numerous wpc products/systems, some of which have UK and European registered designs. Outside of work Gary enjoys spending time with his family, the great outdoors and watching Manchester United.