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DIYing your own decking? Whether using traditional timber deck boards or composite decking, here's everything you need to know to do it yourself. Remember, the foundations are what matters - get that right and you'll have a deck built to last.
Decking ServicesComposite decking has become a popular alternative to traditional timber. Especially for homeowners and commercial spaces looking for a smart, low-maintenance finish. But while it’s often marketed as the “easy option”, composite decking comes with its own rules, limitations and fitting requirements that are easy to overlook.
This guide breaks it all down. We’ll explain what composite decking is made from, how it should be fitted, how much it costs, how it behaves in different conditions, and whether it’s the right choice for your space. All from a practical, real-world perspective.
FMT Solutions have been installing composite decking for residential and commercial properties for years. Find out more about our deck installation and maintenance services here if you want professional support.
Composite decking is manufactured from a blend of wood fibres and recycled plastics, bonded together to create boards that look similar to timber but behave very differently.
Most modern composite boards fall into two categories:
The quality varies significantly between manufacturers. Lower-cost boards may look fine initially but can be more prone to movement, surface wear and colour change. This is one of the reasons professional advice before installation matters. Not all composite decking is created equal.
One of the biggest misconceptions is that composite decking can be installed in the same way as wood. It can’t.
Composite boards rely on precise spacing, specialist fixings and a perfectly level subframe. Unlike timber, composite doesn’t flex or forgive mistakes in the same way. If the groundwork is off, the finished deck will show it... Often within months.
Hidden clip systems are commonly used, which means boards must be aligned accurately from the very first row. Once installed incorrectly, adjustments are difficult without lifting large sections.
Composite decking typically requires closer joist spacing than timber to prevent sagging and movement. This is one of the most common points of failure in DIY builds. But don't panic. This straightforward guide to DIY deck installation will make sure you master the basics.
Joists that are spaced too far apart may not show issues immediately, but over time boards can bow, creak or feel unstable underfoot. This is when it's often easier, and more cost-effective, to contact a professional composite decking installer.
Yes, composite decking can be installed over concrete, but only with the correct subframe system in place.
A common mistake is fixing boards directly onto slabs without allowing for:
Without proper ventilation, moisture can become trapped underneath, leading to long-term issues with fixings, framing and surface performance. A professionally designed subframe ensures the deck remains stable and dry, even when installed over existing patios or concrete bases.
Yes, composite decking does expand and contract, particularly with temperature changes.
This is one of the most important things to understand before installation.
Boards can expand in length and width during warmer weather, which is why manufacturers specify minimum gap requirements at:
Failing to allow for expansion can cause boards to:
This section alone accounts for a large number of composite decking call-outs and repairs.
Composite decking boards typically cost more upfront than timber. Prices vary depending on:
Cheaper options may seem appealing, but lower-quality boards often require more maintenance or replacement sooner.
Composite decking installation is usually more labour-intensive than timber. Precision is key, and fitting takes longer due to:
This is why installation costs can be higher, but also why professional fitting pays off long-term.
While composite decking costs more initially, it often works out more economical over time due to:
With that being said, timber decking can be long-lasting with the proper maintenance and treatment. This bespoke commercial decking we built for The Pear at Parley in Ferndown, Dorset undergoes annual maintenance for heavy usage.
Whether composite decking is slippery depends on board quality, surface texture and installation design.
Higher-quality boards feature textured, anti-slip finishes that perform well even in wet conditions. Drainage also plays a big role, boards must be installed with correct spacing and orientation to allow water to disperse quickly.
Smooth, poorly fitted boards are more likely to become slippery, particularly in shaded or damp areas.
Composite decking is often described as maintenance-free, but in reality, it’s low maintenance, not no maintenance.
Basic care includes:
Professional installation helps here too. Correct spacing and drainage make cleaning easier and prevent algae build-up. The how to maintain your decking guide covers all the basic principles of keeping your composite decking in shape.
Some of the most common issues we see include:
Most of these problems don’t show up immediately. They develop over time and are far more expensive to correct later.
Composite decking works particularly well for:
That said, timber may still suit certain properties better depending on budget, aesthetics and usage. A site visit and honest assessment can save a lot of frustration down the line.
Composite decking demands accuracy. Once boards are down, mistakes are difficult to hide or fix.
Professional installation ensures:
You can contact FMT Solutions for a no-obligation quote on your decking project.
Most high-quality composite decking lasts 20–30 years when installed correctly and maintained properly.
Some fading is normal, particularly in the first few months, but quality boards stabilise and retain colour long-term.
Many boards are made using recycled plastics and wood fibres, making them a more sustainable option than some timber products.
Individual boards can often be replaced, but matching older boards may be difficult if colours have weathered.
Yes, composite decking is commonly used in commercial settings due to its durability and low maintenance.
Composite decking is a solid investment when it’s done properly. While it may look straightforward online, the reality is that fitting, spacing and preparation make all the difference between a deck that lasts decades and one that causes problems.
If you’re considering composite decking, getting expert advice early can save time, money and stress.