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What changes the cost of decking?
Decking costs depend on the size and height of the deck, the boards and the frame beneath them, how the ground is prepared, and extras such as steps, balustrades and lighting. This guide prints no price, so compare written quotes for the same design, boards and frame.
Last reviewed:What goes into a deck
A deck looks simple from above: rows of boards with gaps between them. Most of the cost and most of the life of a deck sit underneath, in parts you will not see once it is finished.
A typical garden deck is built in layers:
- Ground preparation. Turf and topsoil cleared, the ground levelled roughly, and a weed membrane laid.
- Supports. Posts set in concrete, or adjustable pads on paving slabs or a firm base.
- The frame. Bearers and joists, usually treated timber, spaced to suit the boards.
- Boards. Timber or composite, fixed with screws or hidden clips.
- Edges and extras. Fascia boards to hide the frame, steps, balustrades, handrails and lighting.
A well-built frame keeps the boards flat and stops the deck bouncing. A poorly built frame can let a deck down long before the boards wear out.
QuoteZila is starting in Cheshire, with Crewe, Nantwich and Sandbach among the first towns, and anyone in the UK can post a job. This guide does not print a price. It explains what changes the cost of decking, the planning rules and how to compare quotes.
What changes the cost of a deck
| What is being priced | What makes it bigger or smaller | What to ask |
|---|---|---|
| Size | Area of the deck, shape, cut-outs around trees or drains | How the area was measured |
| Height | Ground level, low raised, or high raised on a slope | How high the finished deck will be |
| Boards | Softwood, hardwood, composite, grooved or smooth | Which board, its width and its make |
| Frame | Joist size and spacing, treated timber grade | How the frame is built |
| Supports | Posts in concrete, adjustable pads, existing patio | How the deck will be supported |
| Ground preparation | Turf removal, levelling, weed membrane | Whether this is included |
| Steps and edges | Number of steps, fascia boards, edging | What edge details are included |
| Balustrades | Timber, glass or metal, height | Whether a balustrade is needed or wanted |
| Lighting | Low-voltage lights, sockets nearby | Who does any wiring |
| Waste | Soil, turf, old decking | Whether removal is included |
| 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]. Some decking installers are sole traders below that, so check each total.
Height, slopes and planning
Height changes both the build and the rules. A deck at ground level needs only a low frame. A deck on a sloping garden may need tall posts, bracing, steps and a balustrade, which adds materials and time.
The Planning Portal says putting up decking or other raised platforms in your garden is permitted development, not needing an application for planning permission, provided the decking is no more than 30cm above the ground [S1]. It also lists other conditions, including that decking cannot go forward of the principal elevation of the house, and says these rules apply to houses, not to flats or maisonettes [S1]. Within the grounds of a listed building, the Planning Portal says no decking or platform is permitted under those rules [S1].
If your deck will be higher than that, or you are not sure, ask your council's planning team before you order materials. Permitted development rights can also be removed in some areas, so a quick check is worth it.
A raised deck also needs a safe edge. Ask the installer what balustrade or handrail they would fit, and how high.
Timber or composite boards
The boards are the most visible choice and a big part of the materials cost.
- Softwood. Usually pressure-treated pine or similar. It is the usual lower-cost choice, but needs regular cleaning and treating.
- Hardwood. Denser and longer-lasting timbers, at a higher price, with more work to cut and fix.
- Composite. Boards made from a mix of wood fibre and plastic. They usually cost more at the start but need less finishing.
Board width, profile and fixing method matter too. Hidden clips give a clean surface but take longer than face screws. Grooved boards may look less slippery but hold dirt in the grooves.
Caring for a timber deck
Timber decks need looking after, and that is part of the cost over the years. Ronseal's guidance on looking after decking says new decking should be left to weather so the pre-treatment can wear off, and suggests about six months before the deck is oiled [S2]. After that, a timber deck usually needs cleaning and recoating every so often.
Ask your installer:
- whether the timber is pre-treated, and with what
- when the first oil or stain should go on
- how often they would expect it to need redoing
- how to keep the gaps between boards clear so water drains
Drainage, shade and what is underneath
Decks fail early where water sits on them or under them. Think about:
- Drainage. The ground under the deck should not hold puddles. A slight fall in the boards helps rain run off.
- Air flow. Gaps around the edges stop the frame staying damp.
- Shade. Decks under trees or in shade stay wet longer and can get slippery.
- Access. Drains, stopcocks and inspection covers under a deck need a removable section.
- The house wall. A deck built against the house should not cover air bricks. Ask how the finished boards will sit in relation to the damp proof course.
Ask the installer how they will deal with each of these on your site.
Replacing an old deck
If an old deck is being replaced, the frame matters as much as the boards. Sometimes the boards have worn out but the joists are sound, and only new boards are needed. More often, a deck that has rotted on top has rotted underneath too.
Ask each installer to lift a board or two and check the frame before quoting. A quote to reboard an old frame will look lower than a quote for a new deck, but it is only a fair comparison if the frame is worth keeping. Ask too who takes the old timber away, because a full deck makes a lot of waste.
Decking in Cheshire
When you post a decking job, include photos of the space from a few angles, rough measurements, how much the ground slopes, and whether anything needs removing first, such as turf, an old patio or old decking. An installer covering Crewe, Nantwich, Sandbach or the villages nearby can then judge the frame and supports needed.
Your council's planning team is the place to check local rules for higher decks, rather than relying on what a neighbour built. 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
- how high the deck needs to be, and how much the ground slopes
- your preferred boards: softwood, hardwood or composite
- whether you want steps, a balustrade or lighting
- anything to remove first: turf, paving, old decking
- where drains, covers and air bricks are
- your postcode and when the work could be done
How to compare decking quotes
Check each quote for:
- The size, height and shape of the deck.
- The boards: material, make, width and fixing.
- The frame: timber, joist size and spacing.
- Supports and ground preparation.
- Steps, fascias, balustrades and lighting.
- Waste removal.
- Whether VAT is included, and whether the price is fixed.
Citizens Advice suggests getting written quotes from at least three different traders before choosing one [S3]. It also says a quote is a fixed price, while an estimate is a rough guess, so you might end up paying more [S3]. Ask which you have been given.
Jobs you might post
These are examples, not taken from real job posts. "Build a ground-level softwood deck off the back door, with a weed membrane and one step down to the lawn." Or: "Replace a rotten deck on a sloping garden with a new raised deck and balustrade." Or: "Quote for a composite deck to replace an old patio. Patio slabs can stay as a base if suitable."
Get quotes for decking
Describe the space, the size and the boards you want, 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 if the boundary needs work too. For composite boards, see what changes the cost of composite decking.
Official and public sources
QuoteZila is not affiliated with these organisations.
- Planning for decking: Planning Portal: decking [S1].
- Looking after a timber deck: Ronseal guidance on looking after decking [S2].
- Quotes and estimates: Citizens Advice [S3].
- VAT: GOV.UK on when to register [S4].
Questions about decking costs
How much does decking cost?
This guide does not print a price. The area, the height, the boards, the frame, the ground preparation and any steps or balustrades all change what you pay. Ask each installer to quote for the same size, the same boards and the same frame so the totals can be compared.
Do I need planning permission for decking?
Often not for a low deck at a house. The Planning Portal says decking is permitted development if it is no more than 30cm above the ground, with other conditions. A higher deck or decking at a flat may need permission, and within the grounds of a listed building no decking is permitted under those rules. Check with your council if unsure.
Does timber or composite decking cost less?
It depends on the boards chosen and the life you expect. Softwood boards usually cost less to buy, but they need regular cleaning and treating. Composite boards often cost more at the start and need less finishing. Ask installers to quote both if you are undecided.
When should new timber decking be treated?
Ronseal's guidance says new decking should be left to weather so the pre-treatment wears off, and suggests about six months before oiling. Follow the instructions for the product you use.
Does a deck need a concrete base?
Not usually all over. Most decks sit on a timber frame supported by posts or pads at set points. The ground under the deck is usually cleared and covered with a weed membrane. Ask the installer how the frame will be supported on your ground.
How long does decking last?
It depends on the boards, the frame, the drainage beneath and the upkeep. Ask the installer what life they expect from the materials they propose, and what any manufacturer's warranty covers.
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, patios and garden design
- Carpenters: timber frames and steps
- Gardeners: planting and upkeep around a deck
- Fencing cost: what changes the cost of a fence
- All cost guides
Part of Cost guides. All services
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Related pages
- 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.
- Landscape Gardeners: What Changes the Cost. How landscape gardeners price work: day rates or fixed project prices, design fees, materials, machinery, waste, and what a written quote should list.
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: How to look after decking, Ronseal. Accessed 2026-10-28. https://www.ronseal.com/how-to-guides/how-to-look-after-decking/
- S3: 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/
- S4: Register for VAT, GOV.UK. Accessed 2026-10-28. https://www.gov.uk/register-for-vat