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  • Emily Walker

The Great Decking Debate: Composite vs. Wood – or is there another option?

Composite decking vs modified wood decking
Composite decking vs wood decking

Composite has proven to be the popular choice thanks to its longevity and low maintenance, but choosing the natural charm of wood doesn’t have to be the compromise it’s been made out to be; an emerging contender in the decking realm, modified wood, offers a compelling alternative worth exploring.

Modified wood is natural wood’s beefy, good-looking older brother; it’s better than natural timber in almost every way, but is it better than composite?

So, I suggest that the question you should really be asking is whether you should be using composite or modified wood.

Many find it difficult to decide which is better suited to their needs. The goal of this guide is to provide a detailed comparison of composite decking versus modified wood decking. We'll examine the cost, appearance, durability, maintenance, safety, eco-friendliness, and warranties of each option. By the end, you'll hopefully feel better informed to decide which decking material is right for your next project.


But first, what is composite decking?

Composite decking is produced by combining wood fibres or flour with plastic, often sourced from reclaimed or recycled materials. This combination undergoes a thorough blending process to ensure the wood and plastic are evenly distributed.


The blended material is then extruded or poured into moulds, which shape the decking boards into their desired dimensions. The boards are carefully formed to mimic the natural look and feel of wood.

Once the boards have been shaped, they undergo a curing process that allows them to solidify and strengthen. This process ensures that the composite decking is resilient against warping, cracking, and other forms of damage, even when exposed to the harshest weather conditions.


So, what about modified wood?

Modified wood refers to natural wood that has been altered through chemical, thermal, or other processes to improve certain properties such as dimensional stability, decay resistance, and moisture resistance. Rather than just a surface coating, the wood is modified throughout the entire profile.


The main benefits of modified wood include:

Improved durability - The modification process changes the wood on a molecular level, making it more resistant to rot, insect damage, and moisture. The treatment protects the wood from within, allowing it to last longer outdoors and in wet environments.


Enhanced stability—Treatment reduces the wood's tendency to swell, shrink, twist, and warp when exposed to moisture and humidity changes, making it more dimensionally stable.


Overall, wood modification imparts long-lasting resistance against weathering, decay, and insects. The improved stability and durability allow modified wood to be used in applications where normal wood would fail prematurely. Modified wood can last for decades outdoors with minimal upkeep. Just like composites, its properties vary depending on your choice.



When comparing costs on anything, you need to take a holistic approach; just looking at the square meterage isn’t enough; it's important to look at both installation and material expenses as well as total lifespan costs.


Installation: Popular thinking is that composite decking tends to cost more upfront for installation compared to wood. Composites often require different tools than standard wood decks, resulting in more labour costs. However, there are so many different methods of installation for both woods and composites that to make a sweeping generalisation on which costs less would be irresponsible. Therefore, we can unhelpfully say that these vary wildly depending on the specific products chosen, the calibre of the installer and the method of installation.


Materials: Both composite and modified wood have cheaper options as well as higher-performing, more expensive options, so again, it depends on what you choose. Composite deck boards can cost between £40-£170 per square meter, while modified wood costs anywhere between£40-£150 per square meter.


Lifespan costs: When comparing decking materials, you will obviously consider how long your deck is going to last, but you also need to consider the cost of upkeep. Will you be managing this yourself or paying a professional? Composite usually comes out on top when it comes to maintenance, as most recommendations are for a twice-yearly cleaning, but modified wood is hot on its heels. Unlike natural wood, modified wood, just like composite, only requires two cleans per calendar year; however, most wood, modified wood included, will fade in colour over time to a beautiful silvery grey. Many people prefer this look, but if you want to keep it looking the same as it did the day it was installed, you will need to treat it. Treatments will obviously come at an extra cost, although maybe not as much as you think; there are some outstanding products available. Owatral has a deck paint with a 5-year warranty; their products penetrate deep into the wood and are non-film forming, which prevents cracking, flaking and peeling. Check out their products here.




Composite decking offers a wide range of colour and pattern options to match almost any aesthetic. It is made from a mix of wood fibres, plastics, and other bonding agents that allow manufacturers to easily create different colours and patterns during production. Composite decks are available in solid colours like grey, brown, tan, and black. Multi-coloured variegated options try to mimic the look of real wood with grain patterns. We have yet to find a truly convincing composite; however, there are some very attractive options out there. These colours can fade slightly over time unless you splash out on the pricier versions with fade resistance.


Many people including us here at Grad UK, adore the look and feel of real wood, with its authentic grain patterns. However, when choosing wood, it’s important to understand that natural colour progression over time. Most wood tends to fade to a silver-grey patina with sun exposure, which some people love, so much so that it has led one modified wood company to inject a grey dye throughout the profile of their wood to achieve this very look upon installation (check it out here). Most modified wood (with one exception – find out more) is that you have the option to apply stains or sealants, which can maintain the original wood tone or change it completely. The great thing about this is that should your tastes change, your deck can be treated with whatever colour you desire, giving you infinite options and opportunities to update your style over the years.


Overall, composite decking offers more diversity in colours and patterns off the shelf, while modified wood provides a timeless elegance that can’t be replicated; with wood, you also have the option to treat or stain to maintain its original colour or even change it entirely. However, be aware that some modified woods, such as those that have been chemically modified, do not accept certain treatments due to how they have been modified (look out for our upcoming blog where we compare the different types of modified wood). In the end, it all comes down to personal style and design taste.




When it comes to durability, composite decking and modified wood decking don’t perform all that differently.


Composite decking's composition makes it highly resistant to rotting, cracking, splitting, mould, and insect damage. It maintains its shape and structural integrity through years of exposure to sun, rain, snow, and temperature fluctuations. One downfall of some composite brands noted by industry tradesmen is a tendency for delamination, which is where one layer comes away from another. In this instance, the deck would typically be covered by warranty and hopefully replaced free of charge by the manufacturer.


Modified wood benefits from increased resistance to weather, rot, and insect damage. It holds up far better than unmodified wood and can require little to no maintenance, depending on your choices.




When it comes to maintenance, composite and modified wood decking aren’t as different as you might think.


Composite decking is touted for its low maintenance needs. You just need to clean it periodically with soap and water. Moderate scrubbing may be needed if it gets stained from food, grease, or other spills.


Modified wood decking can be just as simple. Due to its modification, it doesn’t require sealing or treating the same way natural timber does; a good cleaning twice a year is sufficient. If, however, you have decided to treat your wood to achieve a certain look, then this will obviously need ongoing maintenance. Luckily, there are products out there that do not need renewing for up to five years, keeping the maintenance incredibly low but not always as low as composite.


Composite decking used to be the clear winner on maintenance compared to wood, but modified woods have dramatically closed that gap, if not eliminated it entirely.




When it comes to safety, composite decking has some advantages over wood decking. Most composite decking is engineered to have a rough, grooved surface texture that provides more slip resistance, especially when wet. Wood decking can become slippery when wet if not treated with textured finishes.


Fire resistance—No composite decking is completely fireproof. The composite's material composition makes total fire retardancy impossible. However, there are some composites out there with a B fire rating. Wood, by its nature, fuels the spread of fire. That said, certain modified woods can now be fire-treated at an extra cost, but again, this will increase their fire resistance and not eliminate it completely.


Overall, composite decking's slip resistance could make it a slightly safer choice compared to wood decking. However, there are treatments for wood options to combat slip, such as grip strips, but of course, these incur extra costs.




When it comes to eco-friendliness, composite decking and modified wood decking have some key differences.


Composite decking is often made from recycled plastic and wood fibres. Modified wood, on the other hand, uses non-toxic methods like heat treatment for preservation. This avoids the use of chemicals. Wood is also a renewable resource, whereas plastic relies on fossil fuels. In terms of carbon footprint, wood decking performs better over its longer useful life. The trees used are replaced in sustainable forests.


So, while composite decking recycles plastic, modified wood tends to have a lower overall footprint. Composite materials are less easily recycled. Wood also helps capture and store carbon as it grows, offsetting some emissions during harvesting and processing.


When evaluating environmental impacts, modified wood decking is often the greener choice. However, composite decking reduces the demand for virgin plastic and uses recycled materials in its manufacturing process.




One key consideration is the warranty coverage when comparing composite and modified wood decking. Composite decking usually has a decent warranty, typically 10-25 years. However, there is an American composite in the market offering an impressive 50 years on most of its range. Most composite warranty covers the structural performance and, on the more expensive version, even staining and fading. Modified wood generally comes with a longer warranty, depending on what you choose, anywhere from 15 to a whopping 50 years. You’ll end up paying more for the longer-warrantied wood, but it could be worth it for the peace of mind.


The longer warranty periods are definitely a draw; composite can fade and peel over time, and modified wood can still crack or splinter. Luckily, neither suffers from rot, thanks to their manufacturing process.


It's also important to read the fine print on warranty terms and understand what is and isn't covered. Some composite warranties may exclude certain types of damage, like damage from impacts or improper installation. Wood warranties often exclude natural weathering and wear and tear over time. So, it’s important to carefully compare warranty details as you choose your decking material.


Whatever option you choose, you should consider the subframe and not just the decking board. Quite often, composite decking is laid onto a timber frame, which can fail prematurely if measures are not taken to prevent rotting; even then, they have a shorter lifespan than other options out there. As each board type can be laid onto different subframes, we have not included the subframe in our comparison. To learn more about subframes and the pros and cons of the different choices available, we’ll be releasing an article in the next few weeks; subscribe to our newsletter so that you don't miss out.




When deciding between composite and modified wood decking materials, there are pros and cons to consider for both options.


The main advantages of composites are their low maintenance requirements, durability, and resistance to rot, splintering, and cracking. Composites also come in a wide variety of colours and textures to match your style. The downsides are that they are less sustainable, and composites can get very hot in direct sunlight.


For modified woods like pressure-treated lumber, the pros are the natural beauty and wood grain patterns along with their potentially larger lifespan, not to mention being the more sustainable option. Drawbacks include higher costs and potential supply limitations; since modified wood is a speciality product requiring major investments in manufacturing equipment, only a handful of mills and suppliers exist. Lead times may be longer if sourcing modified wood and large-scale builders may need to plan farther in advance than if using typical lumber.



Ultimately, there is no definitive "better" option. The choice depends on your budget and aesthetic preferences.

Composite offers more choices off the shelf with guaranteed minimal maintenance. However, it is impossible to replicate the timeless natural beauty of real wood, and if you, like us, don’t want to compromise on style, then modified wood can offer you the same low maintenance as composite. If you love the natural beauty of wood but don’t particularly like the way it greys over time, you still have the option to prevent this with applied treatments; it’ll mean more maintenance and a bit of cost over time, but it can be totally worth it. If you are looking for the most sustainable product, then modified wood is your best choice.  Do your research to make the best choice for your home, climate, and lifestyle.


No advice can replace your own solid research; we’ve taken our time to do that research on your behalf. We looked at two leading UK composite decking specialists, one from the US and several smaller suppliers. We have also researched four modified wood manufacturers to bring you the article you just read. All the information here was accurate as of March 2024.

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