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What changes the cost of composite decking?
Composite decking costs depend on the board range, whether boards are capped, solid or hollow, the frame underneath, the clips, fascias and trims, and the size, height and shape of the deck. This guide prints no price, so ask installers to quote for the same board range and the same frame.
Last reviewed:What composite decking is
Composite deck boards are made from a blend of wood fibre or flour and plastic, pressed into board shapes. They look like timber from a distance but do not need oiling, staining or sanding. They are heavier than softwood boards, and they behave differently in heat and cold.
Composite boards come in a wide range, and the range is where most of the difference in cost begins:
- Capped or uncapped. Capped boards have a polymer shell around the core. Uncapped boards are the same material all the way through.
- Solid or hollow. Solid boards are heavier and stiffer. Hollow boards are lighter and use less material.
- Grain and colour. Some ranges have a deep wood grain and mixed colours. Others are plainer.
- Edges. Grooved edges take hidden clips. Square edges are face-fixed with screws.
QuoteZila is starting in Cheshire, with Crewe, Nantwich and Sandbach among the first towns. Anyone in the UK can post a job or register a business. This guide does not print a price. It explains what changes a composite decking quote and what to ask before you choose.
What changes the cost of composite decking
| What is being priced | What makes it bigger or smaller | What to ask |
|---|---|---|
| Board range | Make, capped or uncapped, solid or hollow, colour | The exact range and colour quoted |
| Area and shape | Size, curves, angles, cut-outs | How many boards and how much waste is allowed |
| Frame | Treated timber, aluminium or composite joists | What the frame is made of and its joist spacing |
| Supports | Posts, adjustable pads, an existing patio | How the frame will be supported |
| Fixings | Hidden clips, starter clips, colour-matched screws | Which fixing system is used |
| Fascias and trims | Edge boards, end caps, corner trims | Whether edges are finished all round |
| Steps and balustrades | Number of steps, rail material | What extras are included |
| Ground preparation | Turf removal, levelling, membrane, drainage | Whether this is included |
| Waste | Old deck, soil, offcuts | Whether waste is taken away |
| VAT | Whether the business is VAT registered | Whether the total includes VAT |
A business must register for VAT when its taxable turnover goes over £90,000 [S4]. Many installers are sole traders, so check every total for VAT.
The frame under composite boards
The frame is easy to overlook because it is hidden, but composite boards depend on it. Board makers usually set a maximum spacing for the joists under their boards, and a frame built for timber boards may not meet it.
Installers build composite deck frames in a few ways:
- Treated timber joists. Common and adaptable. The frame may need protecting where boards meet it, and timber will not last forever.
- Aluminium joists. Lighter and rot-free, at a higher cost, and often sold as a system with the boards.
- Composite joists. Sold by some board makers for low decks.
Ask each installer what they would use, why, and whether their frame meets the board maker's instructions. If you are reusing an old frame, ask them to check every joist.
Heat, expansion and gaps
Composite boards move with temperature. They expand in heat and shrink in cold, often more than timber does along their length. Board makers set gaps at the ends and sides of each board to allow for this, and a deck fitted without them can buckle.
Dark boards can also get hot in strong sun. If the deck faces south or you have young children or pets, ask about lighter colours or shade.
Ask each installer:
- what gaps they leave at board ends and against walls
- how they deal with long runs and joints
- whether the board maker gives any guidance for hot spots, such as under glass
Warranties and the board maker's instructions
Many composite board ranges come with a manufacturer's warranty against things like fading or staining. Warranties usually depend on the boards being installed to the maker's instructions, using approved clips and frames.
Before you choose, ask:
- what the board warranty covers and for how long
- whether the installer's fitting meets the conditions for the warranty
- whether the installer gives their own warranty on the workmanship
- what paperwork you will get when the job is finished
Your rights over the installation itself do not depend on a warranty. Citizens Advice says the Consumer Rights Act 2015 requires reasonable care and skill when work is done [S3].
Composite or timber over the years
The comparison with timber is not only about the price on the day. A timber deck usually needs cleaning and a fresh coat of oil or stain every so often, which costs time or money each time. A composite deck usually needs cleaning but no recoating.
If you are weighing the two, ask installers to quote both, and think about how long you expect to stay in the house and how much upkeep you are happy to do.
Planning and raised decks
The board material makes no difference to planning rules. The Planning Portal says decking or other raised platforms in a garden are permitted development, without a planning application, provided the decking is no more than 30cm above the ground [S1]. It lists other conditions, and says the rules apply to houses rather than flats or maisonettes [S1].
If your deck will be higher, or you live in a listed building, check with your council's planning team first. Raised decks also need safe edges, so ask about balustrades.
Cleaning and upkeep
Composite decking still needs some care. Leaves, dirt and algae build up, especially in shade, and gaps between boards need keeping clear so water drains.
Ask the installer or board maker:
- how the boards should be cleaned
- whether pressure washing is allowed
- which cleaning products to avoid
- how a damaged board can be replaced later
Keep a few spare boards and clips from the job, because colours can change between batches.
Composite decking in Cheshire
When you post a composite decking job, include photos, rough measurements, the height you want, and the board range or colour if you have chosen one. Say whether an old deck or patio is there now. An installer covering Crewe, Nantwich, Sandbach and the villages nearby can then suggest a frame and say whether the old base can stay.
If you have not chosen boards yet, ask each installer which ranges they fit and why. Anyone in the UK can still post a job or register a business on QuoteZila.
What to have ready before you ask for quotes
- photos of the space and rough measurements
- the height you want the deck, and how much the ground slopes
- the board range and colour, if chosen
- whether you want hidden clips or face fixings
- steps, balustrades or lighting you would like
- what needs removing first
- your postcode and when the work could be done
How to compare composite decking quotes
Check each quote for:
- The exact board range, colour and type.
- The frame material and joist spacing.
- Supports and ground preparation.
- Clips, screws, fascias and trims.
- Steps, balustrades and lighting.
- Warranty paperwork for the boards and for the workmanship.
- Waste removal.
- Whether VAT is included, and whether the price is fixed.
Citizens Advice suggests getting written quotes from at least three different traders [S2]. It also says to be cautious if a price is a lot lower than the other quotes [S2]. With composite decking, a lower quote may be for a lower-cost board range or a frame that does not meet the board maker's spacing.
Jobs you might post
These are examples, not taken from real job posts. "Supply and fit a grey capped composite deck behind the house, ground level, with fascia boards on two sides." Or: "I have bought composite boards and clips. Please quote to build an aluminium frame and fit them." Or: "Replace an old timber deck with composite. Please check whether the existing frame can be reused."
Get quotes for composite decking
Describe the space, the size, the height and the boards you have in mind, with photos and your postcode. Up to five matched local businesses can reply [QZ2]. QuoteZila is free for customers and local businesses [QZ1].
Honest status: QuoteZila is new. We're starting in Cheshire, beginning with Crewe, Nantwich and Sandbach, and growing area by area. Anyone in the UK can still post a job or register a business. How fast you get quotes depends on how many local businesses have joined near you. Businesses can register and receive jobs straight away. We don't check insurance, qualifications or registrations, so please check these yourself before you hire.
Posting a job is not open yet
See the landscapers page, the carpenters page or the fencing cost guide for boundaries. For timber decks, see what changes the cost of decking.
Official and public sources
QuoteZila is not affiliated with these organisations.
- Planning for decking: Planning Portal: decking [S1].
- Quotes: Citizens Advice: before you get work done on your home [S2].
- Poor work: Citizens Advice: problem with building work or home improvements [S3].
- VAT: GOV.UK on when to register [S4].
Questions about composite decking costs
How much does composite decking cost?
This guide does not print a price. The board range, the frame, the fixings and trims, the deck size and height and the ground preparation all change the total. Ask each installer to name the exact board range and colour in the quote so you can compare like with like.
Is composite decking worth the extra over timber?
It depends on what you value. Composite boards usually cost more to buy but do not need oiling or staining. Timber usually costs less at the start but needs regular treatment. Compare both over the years you expect to keep the deck.
What is capped composite decking?
Capped boards have a tough outer shell wrapped around the composite core. The shell is meant to resist staining and fading. Uncapped boards have the composite mix all the way through. Ask the installer which type their quote is for.
Can composite boards go on an old timber frame?
Sometimes, but only if the frame is sound and the joists are spaced to suit the boards. Many board makers set a maximum joist spacing. Ask the installer to check the frame and the board maker's instructions before agreeing to reuse it.
Do I need planning permission for a composite deck?
The board material makes no difference. The Planning Portal says decking at a house is permitted development if it is no more than 30cm above the ground and meets other conditions. A higher deck may need permission, so check with your council.
What can I do if the deck is badly fitted?
Citizens Advice says the Consumer Rights Act 2015 requires reasonable care and skill while the work is done. Raise problems in writing with photos as soon as you find them.
Does QuoteZila check the installers?
No. We don't check insurance, qualifications or registrations, so please check these yourself before you hire. You can report a quote or a business from your job page.
Related guides
- Landscapers: decks and garden layouts
- Carpenters: frames, steps and balustrades
- Fencing cost: what changes the cost of a fence
- All cost guides
Part of Cost guides. All services
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Related pages
- Decking Cost: What Changes the Price of a New Deck. What changes the cost of a new deck in Cheshire: size, height, timber or composite boards, the frame and footings, steps and balustrades, and planning rules.
- Garden Renovation: What Changes the Cost. What moves the price of renovating a garden: clearance, levels and drainage, paving, lawn and planting, boundaries, trees, waste, and doing it in stages.
Sources
- QZ1: QuoteZila product fact. QuoteZila home and FAQ copy.
- QZ2: QuoteZila product fact. QuoteZila FAQ "How does getting quotes work?".
- S1: Planning Permission: Decking, Planning Portal. Accessed 2026-10-28. https://www.planningportal.co.uk/permission/common-projects/decking/
- S2: Before you get work done on your home, Citizens Advice. Accessed 2026-10-28. https://www.citizensadvice.org.uk/consumer/getting-home-improvements-done/before-you-get-building-work-done/
- S3: Problem with building work, decorating or home improvements, Citizens Advice. Accessed 2026-10-28. https://www.citizensadvice.org.uk/consumer/getting-home-improvements-done/problem-with-home-improvements/
- S4: Register for VAT, GOV.UK. Accessed 2026-10-28. https://www.gov.uk/register-for-vat