Top Tips For Composite Deck Building

Decking is a great way to enjoy more of your outdoor space and give your garden versatility. It can be a wonderful solution to uneven or sloped gardens.

If you are considering decking for your property, you will have lots of decisions to make. The deck board and sub-frame material will make a difference in cost, style, durability, and longevity.

One of the most popular decking options is composite decking. The Forma and Clarity composite decking options at Ecoscape give property owners a high-quality, low-maintenance option that looks great.

This guide will take you through the top tips for composite deck construction.


Composite Decking Explained

The composite decking provided by Ecoscape is a combination of recycled plastic composites and reclaimed wood fibres. This provides homeowners an eco-friendly option that avoids the maintenance, splinters, and warping that traditional wood decking suffers from.

The Clarity range is the 1st generation Wood Plastic Composite Decking with great slip resistance and a 20-year warranty.

The Forma range is 2nd generation co-extruded Wood Plastic Composite Decking with an impressive colour guarantee and a 25-year warranty.


Top Tips For Composite Deck Building

If you have experience with this kind of task, you might want to take on the job yourself rather than employing professional deck builders.

This type of job should only be carried out if you are confident that you will be able to carry out the supplier’s instructions safely.

If you plan to carry out your own deck construction, the following tips will help you stay on track.


Plan the Entire Project

Determining the scope of the entire project can be challenging, but it should help you to plan the work that needs to be carried out. This is important when you are managing the project yourself.

If you are starting from scratch, you will have to create an even and sturdy subframe capable of bearing the deck weight.

If you are removing existing decking, you will have to factor in the time and effort it will take to rip out the old deck and how you plan to dispose of it.

Existing deck owners should also consider whether the current frame is suitable for a composite deck.

If the previous deck were made with timber boards, the joists would typically be further apart than the recommended guidelines for composite decking.

Composite decking is significantly heavier than wooden deck boards, which should also be factored in when dealing with an existing subframe.

When planning the project, you should also consider the location, how the sun moves around your garden, and access routes. You will then be able to calculate the desired decking area.


Choose the Best Composite Decking Boards for your Needs

You should also check the specs of the decking boards you plan to buy to ensure they are suitable for the job. Not all composite decking is of the same quality, so buying cheaper deck boards might not be cost-effective in the long term.

The great choice of composite decking available at Ecoscape undergoes rigorous testing and has ISO9001, ISO14001, FSC, RIBA CPD, and BALI third-party certification.

Budget will typically play a part in the decking you choose. Whenever possible, check the certifications, warranties, and guarantees that the decking has to choose the most suitable options for your home.


Ensure Your Plans Adhere to Building Regulations

Contacting your local planning authority will determine whether your decking project requires permission.

In the UK, you should not need permission for decking that is not raised more than 30 cm above the ground.

The decking and other home extensions or outbuildings cannot cover more than 50% of the garden.

Listed buildings and buildings in National Parks and Areas of Outstanding Beauty will also have further considerations that need to be investigated before work commences.

Speaking with your local authority and advising them of your plans will help to determine what will be accepted and what could be rejected. This will help you to make adjustments to ensure your plans can go ahead.


Plan for Wastage

Calculating the area that you plan to deck is essential to understanding the amount of decking you will need to buy.

Buying the exact amount of decking for the desired area is risky. Allowing an additional 5% for wastage will usually be sufficient to ensure that mishaps or miscalculations are covered.

Experienced professionals will be able to measure the area and plan accordingly.

If you plan on installing your own decking, speaking directly with the supplier will help you get exactly what you need.


Ensure you Have the Correct Tools

Another reason to employ experienced builders to install a new deck is that they will have the tools needed to carry out the job.

A well-stocked toolbox will typically have the tools needed to carry out some aspects of the job. However, more specialist equipment will be required for other tasks. These tools include;

  • Cordless drill/driver
  • Power plane
  • Chalk line
  • Mitre saw
  • Circular saw
  • Corded drill


The supplier directions will advise the installer on what steps are necessary to safely install their specific product. Taking a look at the directions beforehand will help you to plan ahead for the tools needed.


Follow Supplier Instructions

Following the supplier’s instructions is essential. There can be subtle differences in different composite boards that make a considerable difference to the safety and appearance of your decking.

At Ecoscape, we have comprehensive installation instructions for each of our products. Deviating from these instructions to save time or money will compromise the quality of the build.


Use Supplier Materials

Following directions provided by the supplier is essential, as is using the materials that are provided with the composite boards.

Suppliers design specific parts to work directly with their products. Using different parts can result in poor performance, issues with appearance, or, more importantly, it can compromise the safety of the decking.

The parts provided are designed to improve the aesthetics of the design and are tailored to the size and weight of the product you buy.


Plan Your Subframe Accordingly

One of the most important decisions you will have to make when installing decking is about your subframe.

The subframe provides a solid base that provides stability for your decking area.

The longevity of your decking relies on having a solid, long-lasting base. The materials you choose will have a significant bearing on this.

You will have to consider the weather and environment of the area where the decking is to be installed to make the most suitable decision.


Subframe Materials

The decision of choosing your subframe material should be based on the deck board materials and how you plan to use your decking.

If the decking is purely for seating, the subframe would not have to carry as heavy a burden as if you planned to install a hot tub.

Different materials will also last longer with less upkeep. Here are the main subframe materials to choose from;



Wooden subframes are relatively common because they are a low-cost option that is easy to work with.

Pressure-treated wood options are best as they provide excellent strength and are better at resisting rot, decay, and pests.

Wood subframes are not as durable as other options, and poor drainage can speed up the rate of decay.

Wood can also expand and contract in different weather. This will impact the finish of the deck and can lead to uneven areas. At Ecoscape, we recommend that a decking tape is used with all timber substructure.



The excellent benefits listed for composite decking materials are also present when using them as a subframe material.

Strength, durability, and resistance to rot are all essential for a long-lasting subframe that can support your decking.

While plastic deck joists are strong, they are not as strong as aluminium options.

Composite materials are a relatively low-priced option. However, support will typically be required, which can drive the cost up.



One of the most popular subframe material choices is aluminium, and this is because it is extremely strong and does not rot or absorb water.

The expansion and contraction of aluminium is minimal, making it perfect for this kind of job.

Because aluminium is so strong, the thickness of the frame would be around half the size of a wooden frame when providing the same strength.

Brackets are needed to fix deck joists together, so it can take longer than a wooden frame to install. Unless you are using a plastic pedestal system or laying the joists straight on to hard standing, then no brackets are needed.

Aluminium is one of the more expensive options, but its strength and durability make it a worthwhile investment.



Using recycled plastic, plastic deck joists can be relatively good value especially with the recent increase in timber prices. They are durable, water-resistant and environmentally friendly. The 50x50mm joists can span 600mm and the 125x50mm joists can span up to 1500mm.

Installation is similar to wooden joists, but the material is stronger so sometimes pre drilling is necessary.



A solid foundation is essential for your decking. Concrete foundations are a popular choice, but it is essential that drainage is taken into account at this stage.

The depth of the foundations should also consider frost depth in susceptible areas.


Joist Measurements

The strength of joists will determine the correct measurements needed to support your decking. Our installation guide covers the spans for our plastic and aluminium joist range.

A composite decking surface will be significantly heavier than wood. Because of this, the joists in a timber frame will have to be closer together to provide adequate support.


Double Joist Joints

Where the boards on your decking surface join, double joists will provide additional support that will hold each board securely. This is an advisable technique to use when dealing with heavy composite decking.


Cover Joists

If you are using timber joists, covering them to protect against standing water will help to prolong their life and minimise the risk of rot.

When it rains, water will fall between the gaps between deck boards. This can land on the joists and soak in.

When covering joists, you should take into account their visibility, so you don’t ruin the overall aesthetics of your decking. We strongly recommend using our decking tape.


Space Out Deck Boards

The gaps between deck boards are needed to improve drainage. A gap of around 5mm should be suitable for this.

Regular upkeep of your deck to ensure the gaps don’t get filled with dirt or debris is essential.

If dirt is allowed to fill the gap, standing water can make deck boards slippery.

Taking this into account when laying deck boards and regularly removing dirt will help to minimise this risk.


Leave Screws Flush

If you are using screws during installation, ensuring they are left flush with the surface can improve the overall aesthetic and minimise the risk of water pooling.

Many people rely on the screw to do the work of pulling the boards tight. By applying pressure to the board, you will avoid having to screw too tightly to achieve the same result.


Use Under-Mounted Deck Fasteners

Screws don’t always give a clean finish, and many suppliers will include under-mounted deck fasteners.

This is a great option for raised decks and sees a bracket screwed to the joist and the underside of the deck board.

This can be a time-consuming way to secure your deck, but it leaves a great finish on the side that is visible.

Under-mounted deck fasteners remove the need to screw holes in the visible side of the decking, which looks better and protects you against unsightly mistakes.


Plan Ahead to Prevent Vermin from Getting Below Decking

Composite decking care is relatively straightforward, and brushing the deck to keep the gaps clear is essential. Dirt and debris can then fall under the boards, and if there are food remnants, this can attract vermin.

Blocking off potential entry points should stop animals from getting beneath the decking and nesting.

Mesh can be a great way to block off any entrances, and specialist rodent-proof mesh will stop them from getting beneath.


Account for Drainage

Drainage is essential both on your new deck and beneath it. Laying your deck boards with a deck gradient of around 1% to 1.25% will not be noticeable when using it but will help water to run off.

Your boards should be laid with the grooves leading down the gradient to ensure easy runoff.

Below deck drainage solutions should be investigated when setting foundations to ensure the subframe is not exposed to standing water.

Standing water on deck can result in a slippery surface, mould, and mildew. Standing water below the deck can result in the integrity of your subframe being compromised.


Why Choose Composite Decking?

So why are so many consumers choosing composite options over wood decking? There are many reasons that composite deck boards are proving to be so popular, including;


Low Maintenance

One of the main benefits of composite decking over wood decking is that it is low maintenance.

Wooden decking requires regular maintenance, including staining and treatments to help protect it from the weather and pests like woodworm.

Composite decking does not warp, splinter, or split like wood, and you won’t have to worry about rot.

Cleaning composite decking is straightforward. Regularly sweeping dirt and debris will stop the gaps between boards from clogging and affecting drainage.

When you want to clean a composite deck, sweeping debris, hosing it down, and scrubbing it with warm soapy water will get it back to its best.



The durability of composite decking is one of its best features. The rot-resistant material is perfect for UK gardens and guarantees a significantly longer lifespan than wooden options.

The tough-wearing surface won’t scuff or scratch easily, making it a great choice for people with children or pets.

The colour guarantee with Ecoscape Forma composite decking gives peace of mind to consumers who won’t have to worry about their decking looking tired and faded.


Slip Resistance

Some decking surfaces can become slippy in the rain or when they start to get dirty. Thankfully composite has excellent slip resistance.

We ensure all our decking goes through stringent slip-resistance checks.

It is important to remember that all decking can become slippy in snowy or icy conditions. Standing water can also be problematic, so the correct measures must be taken during deck construction to allow proper drainage.



The appearance of your deck is important. Composite decking has come a long way since it was first produced, and there is a great selection of finishes, including wood grain wide groove and narrow groove.

You will also have a great choice of colour options to suit an existing colour scheme or go for something different.


Easy Installation

Composite decking is relatively straightforward to install, making it a popular choice among consumers and deck builders.

Installing a composite deck can still be challenging, especially if you don’t have experience.

It is recommended to go with professional deck builders to install your composite decking to avoid issues. Their experience will help you get the performance and longevity possible with this excellent choice.

Failure to properly install decking can lead to costly repairs or even collapse. Safety should be the main priority during deck construction, so following the tips above should help.



How long does it take to install composite decking?

Composite decking will typically take between 1 and 3 days to install. Installers have informed us that they can build and lay a 10m2 substructure in a day.

The length of time it takes to install composite decking will depend on a number of factors, including how big the deck is going to be.

Installing the subframe can also be a time-consuming part of the process, especially if the garden needs work.


How much does labour cost for composite decking installation?

Labour costs should cost around £150 – £200 per day in the UK for decking installation.

These costs will vary based on the installer and your location.

The overall cost of installation for your new deck will depend on how long it takes for the work to be carried out.

Choosing decking installation services can be made easier by searching for recommended installers and asking for quotes based on the work needed.


Does composite decking need a base?

Yes, composite decking should be installed on a solid base or subframe. This is needed to properly support the decking and ensure it maintains a high level of performance and safety for as long as possible.


Should you waterproof composite decking?

No, you do not need to waterproof composite decking. While you will have to seal wood decking, this is not required with composite decking, thanks to the plastic materials used to create it.

A drainage system should be set up to remove surface water from your deck surface. Drainage beneath your deck is also essential in protecting the joists.


Can I install composite decking?

Composite decking is relatively straightforward to install by following the supplier’s instructions.

You should only install your own decking if you are confident that you can do this safely.

Repairing poorly installed composite decking can be costly, and failure to install it correctly can result in safety concerns.


Final Thoughts

There are so many great benefits to installing composite decking, so it is important you do it correctly.

Professional installation is recommended unless you have experience, and following the supplier guidelines is essential.

The top tips for composite deck building provided above should help anyone that is planning an installation project, and thorough planning will be required to ensure the job goes correctly. If you need help with any aspect of your composite decking project, don’t hesitate to get in touch.

Checking planning and building code regulations before starting is advised to minimise the risk of plans being rejected.

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.