Does Composite Decking Get Hot in the Sun?

Yes, composite decking can get hot in direct sunlight – just like timber decking, paving, artificial grass and other outdoor surfaces. However, how hot it feels underfoot can vary considerably depending on the colour of the decking, board composition, surface finish, amount of direct sunlight, air temperature and location of the deck.

This is an important consideration when choosing decking, particularly for south-facing gardens, exposed roof terraces, pool surrounds and areas where children or adults may regularly walk barefoot.

One of the most common questions we hear when discussing composite decking is: Will it become too hot in summer?

There isn't a simple yes-or-no answer. Understanding what causes a decking surface to heat up can help you choose a more suitable board and design the surrounding outdoor space accordingly.

Why Does Composite Decking Get Hot?

Any outdoor surface exposed to sunlight absorbs solar energy.

As the surface absorbs this energy, its temperature rises. How quickly it heats up and the temperature it eventually reaches depend partly on the material and partly on the surrounding conditions.

Composite decking is generally manufactured using a combination of materials that can include wood fibres, polymers and other additives, although the exact construction varies considerably between manufacturers.

Different composite boards therefore don't necessarily behave identically in strong sunlight.

The surface temperature can be influenced by:

• decking colour;

• board composition;

• surface texture and finish;

• strength and duration of direct sunlight;

• air temperature;

• wind and ventilation;

• surrounding walls and glazing;

• orientation of the garden or terrace;

• nearby shade;

• time of day.

This is why saying simply that "composite decking gets hot" doesn't tell the whole story.

Does Dark Composite Decking Get Hotter?

Colour is one of the most important considerations when choosing decking for a very sunny location.

As a general physical principle, darker surfaces tend to absorb more solar radiation, while lighter surfaces generally reflect more of it.

This means a very dark grey or black decking board exposed to strong direct sunlight can potentially become noticeably hotter than a lighter-coloured alternative under similar conditions.

This doesn't mean dark composite decking should always be avoided.

Anthracite, charcoal and dark brown boards can look excellent against contemporary properties and modern landscaping. However, if the deck receives intense sunlight throughout much of the day and will frequently be used barefoot, surface temperature should form part of the product-selection process.

Appearance shouldn't be the only consideration.

What About South-Facing Gardens?

Garden orientation can make a significant difference.

A south-facing garden in the UK can receive prolonged direct sunlight, particularly during summer. A deck positioned in an open part of that garden may consequently receive several hours of strong solar exposure.

South-east and south-west facing gardens can also experience significant exposure, although the timing differs.

A south-east facing deck will generally receive stronger sunlight earlier in the day, while a south-west facing space can receive substantial afternoon and evening sun.

The surrounding property also matters.

Trees, neighbouring buildings, fences, pergolas and the house itself can create shade at different times.

For this reason, knowing that a garden faces south isn't enough by itself. We also consider where the deck is positioned and when it receives direct sunlight.

Can Composite Decking Become Too Hot to Walk On?

Under sufficiently strong sunlight, an outdoor surface can become uncomfortable for bare feet.

Whether a particular composite board reaches that point depends on the product and environmental conditions.

This is especially worth considering for:

• families with young children;

• areas around swimming pools or hot tubs;

• barefoot seating areas;

• sunny roof terraces;

• highly exposed balconies;

• properties with large south-facing gardens.

If barefoot comfort is important, we recommend considering surface temperature before choosing the final colour and product.

A sample viewed indoors in a showroom tells you very little about how that same material will feel after several hours in direct summer sunlight.

Composite Decking vs Timber: Which Gets Hotter?

It is difficult to make a universal statement that composite decking is always hotter than timber because there are many different types of both.

A pale natural timber board and a dark composite board are not a like-for-like comparison.

Likewise, different composite formulations and surface technologies can behave differently.

Colour alone can make a substantial difference.

When comparing materials for a particular project, it is therefore better to compare the specific products and colours being considered rather than relying on a general "timber vs composite" rule.

Does Millboard Decking Get Hot?

Millboard should also be considered separately rather than assuming that every product commonly grouped under "composite decking" behaves identically.

Millboard has a different construction from many conventional wood-plastic composite boards.

Its surface, composition, colours and manufacturing technology differ from standard WPC decking, so we recommend evaluating it as a specific decking system.

We've covered this separately in our guide:

Does Millboard Decking Get Hot in the Sun?

This allows us to compare Millboard properly rather than making a general claim that applies to every composite-style decking product.

Does the Decking Surface Texture Affect Heat?

Surface texture can influence how a decking board feels underfoot, although colour and solar exposure remain major considerations.

Modern composite boards are available with a wide range of finishes, from relatively smooth surfaces to deeply embossed timber-grain patterns.

The way your foot contacts the surface can affect the sensation of heat, while different finishes may also behave differently in sunlight.

However, texture shouldn't be used as a substitute for evaluating the actual product.

If heat is a major concern, look at the manufacturer's technical information and, where possible, compare physical samples under realistic conditions.

Do Surrounding Walls Make Decking Hotter?

Potentially, yes.

The microclimate around a deck can make a significant difference.

For example, a deck enclosed by walls can receive direct sunlight while having less airflow than an open garden.

Large areas of glazing can also influence local conditions, and reflected sunlight can sometimes concentrate additional solar energy onto external surfaces.

Similarly, roof terraces can be particularly exposed because they may have very little natural shade.

This is why decking selection should be considered as part of the whole property and landscape, not just by looking at an individual board sample.

Does the Decking Subframe Affect Surface Temperature?

The subframe is primarily selected for structural performance, durability and compatibility with the decking system rather than as a way of controlling board surface temperature.

Timber, aluminium, recycled plastic and steel frames each have their own applications.

Good ventilation beneath decking is important for the overall construction, but it shouldn't be assumed that changing the subframe will solve a surface-temperature problem caused by hours of strong direct sunlight.

If overheating is a concern, decking colour, product selection and shade are generally more relevant design considerations.

Can You Reduce How Hot Composite Decking Gets?

You can't prevent an exposed outdoor surface from absorbing heat completely, but thoughtful design can make the space more comfortable.

Choose the Colour Carefully

If the deck will receive intense sunlight for much of the day, consider comparing lighter and darker colours rather than choosing purely on appearance.

A lighter board may be worth considering where barefoot comfort is a priority.

Introduce Shade

Shade can have a major impact on surface temperature.

Depending on the design, this could come from:

• pergolas;

• retractable awnings;

• parasols;

• trees;

• planting;

• covered seating areas;

• architectural shading.

A pergola can be particularly useful because it can form part of the overall outdoor design rather than being added purely to deal with heat.

Think About Where Different Materials Are Used

Not every part of a garden has to use the same surface.

A larger outdoor transformation might combine decking with porcelain paving, planting and other landscaping materials.

This allows materials to be selected according to how each part of the garden will be used.

Consider How You Actually Use the Garden

A deck designed primarily for outdoor dining while wearing footwear has different requirements from a pool surround where people will regularly walk barefoot.

Product selection should reflect actual use rather than simply following a current design trend.

Should You Hose Down Hot Composite Decking?

Water can temporarily cool a hot surface, but we wouldn't recommend designing a deck on the assumption that it will need to be sprayed with water whenever the sun comes out.

It is better to select an appropriate product and design the space around its intended use.

Any cleaning or maintenance should also follow the particular decking manufacturer's recommendations.

Does Composite Decking Melt or Warp in Hot Weather?

Normal UK summer temperatures should not automatically cause a correctly specified, good-quality composite decking system to fail.

However, composite products can experience thermal expansion and contraction as temperatures change.

This is one reason correct installation is so important.

Manufacturers normally provide requirements covering matters such as:

• board spacing;

• expansion gaps;

• end gaps;

• joist centres;

• fixing systems;

• distances from walls and fixed objects;

• installation conditions.

These requirements vary between products.

There is no single universal "UK regulation" specifying one expansion gap for every composite decking board.

The manufacturer's current installation instructions should be followed for the particular system being installed.

We'll cover this subject in detail in our dedicated guide:

What Gap Should You Leave Between Decking Boards?

Can Reflected Sunlight Damage Composite Decking?

This is a separate issue from ordinary summer heat and is worth considering around highly reflective glazing.

Under certain circumstances, sunlight reflected or concentrated by particular types of glass can create unusually high temperatures on nearby materials.

This isn't unique to decking.

Where a deck will sit close to substantial areas of glazing, particularly where there is a known history of concentrated reflection, the conditions should be assessed and the decking manufacturer's guidance checked.

Is Composite Decking Suitable for a South-Facing Garden?

In many cases, yes.

Having a south-facing garden doesn't mean you can't use composite decking.

It simply means that sun exposure should be considered when selecting the product and colour.

We would look at:

• which direction the garden faces;

• where the proposed deck will sit;

• how many hours of direct sunlight it receives;

• whether there is existing shade;

• the board colour;

• how the deck will be used;

• whether people regularly walk barefoot;

• whether future shading is planned.

A sunny garden can actually be one of the best places for an outdoor living space. The important thing is choosing materials with those conditions in mind.

What Colour Composite Decking Is Best for a Sunny Garden?

There isn't one colour that is universally best.

Lighter and mid-tone colours are worth considering where reducing heat absorption is particularly important.

However, colour also needs to work with the architecture and surrounding landscape.

For example, a contemporary property with anthracite windows might naturally suit a darker decking board, while warm oak or natural timber tones can complement brickwork, rendered walls and planting.

Sometimes the best solution is not simply choosing the lightest possible decking but balancing appearance, exposure, maintenance and intended use.

Should Heat Stop You Choosing Composite Decking?

For most UK gardens, surface temperature is one consideration among several, not necessarily a reason to reject composite decking.

Composite decking offers advantages that can include low maintenance, consistent appearance and resistance to many of the maintenance issues associated with traditional timber, depending on the particular product selected.

The important point is to avoid assuming that every composite board performs identically.

Before making a decision, compare:

• product construction;

• colour;

• surface finish;

• warranty;

• maintenance requirements;

• installation specification;

• expected exposure;

• manufacturer information.

If you're comparing premium alternatives, our guides to Millboard vs Composite Decking and Hardwood vs Composite Decking will help explain the differences.

Choosing Decking for a Sunny Garden

The best decking isn't simply the board that looks best on a small sample.

A good decking design considers the property, orientation, sunlight, drainage, structure, surrounding landscaping and how the outdoor space will actually be used.

For a highly exposed south-facing garden, we may recommend comparing several board colours in the actual location before making the final decision.

For larger outdoor transformations, we can also consider shade, pergolas, planting, seating and different surface materials as part of the overall design.

At Decking Gurus, we design and install composite decking and premium Millboard decking across London, Essex and the Home Counties, from residential gardens and raised decks to balconies, roof terraces and commercial outdoor spaces.

Our Decking Advice & Guides series provides practical information about the decisions that affect how decking looks and performs, including materials, subframes, drainage, lighting, balustrades and common installation problems.

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If you're currently deciding which decking is right for your property, you may also find these guides useful:

Does Millboard Decking Get Hot in the Sun? A closer look at Millboard specifically and what to consider for sunny outdoor spaces.

Millboard vs Composite Decking: What's the Difference? Understand the differences in construction, appearance, maintenance and performance.

Hardwood vs Composite Decking: Which Should You Choose? Compare natural hardwood with modern composite alternatives.

What Gap Should You Leave Between Decking Boards? Understand expansion, drainage and manufacturer spacing requirements.

Decking Lighting Ideas: Where Should You Position Your Lights? Plan lighting alongside the deck rather than treating it as an afterthought.