Garden & outdoors
Decking cost calculator
Decking turns a patch of lawn into usable space for a modest cost, and a ground-level deck is a very achievable DIY project. A level base and accurate joists are the foundation of a good result.
- Full DIY
- £610
- Smart Hybrid
- £610
- Full Trade
- £990
Typical mid-range job, Midlands rates. Yours updates below.
Updated November 2026. Estimates based on typical UK prices.
Cost calculator
Price this job three ways
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Smart Hybrid saves £380 against a full trade job.
Smart Hybrid
You take on what you can, a trade handles the rest.
£610
- Materials
- £612
- Labour
- £0
- You take on: build and lay deck.
- Everything else stays with a trade.
Turn this into a plan
Get the order of work, who to book and a budget tracker, all editable.
Order of work for this job
A typical order. Always confirm timing with whoever you book, since some steps can overlap.
- 1
Fitting
- Build and lay deckYou · ~1.5 days
How we worked out the materials›
- Deck boards£39212 m² of deck + 10% wastage for cuts = 13.2 m²
- Joists£2209 joists (spaced 0.4 m) × 4 m = 36 m of timber ÷ 3.6 m lengths = 10 lengths
Estimates only, based on regional averages. Always get 2 to 3 written quotes from local trades.
The price
What affects the cost?
- 1
Deck area
Boards and joists scale with area. A bigger deck costs more both in material and time.
- 2
Board material
Pressure-treated softwood is cheapest. Hardwood and composite cost more but last longer and need less upkeep.
- 3
Raised or ground-level
Raised decks need posts, concrete footings and sometimes balustrade, which add cost.
- 4
Ground preparation
Levelling, clearing and laying a weed membrane takes time and materials.
- 5
Balustrade and steps
Rails and steps add cost, and are required if the drop is more than 600mm.
Be honest with yourself
Can you do this yourself?
You can do
- The whole job for a ground-level deck
- Laying the base and frame
- Fitting boards and fascia
- Staining or oiling
Leave to a pro
- Large raised decks with deep footings
- Anything close to a boundary or over 30cm that may need planning permission
- Balustrades on high decks (these need to be strong)
The rules
Decking more than 30cm above ground level generally needs planning permission, as does covering more than half your garden. Guards (balustrades) are needed where the drop is more than 600mm.
DIY guide
How to build a deck, step by step
Tools you'll need
- Circular or mitre saw
- Cordless drill and driver
- Spirit level
- Tape measure and string line
- Spade and rake
- Set square
Materials
- Deck boards
- Joists and bearers (treated timber)
- Posts and concrete (for raised decks)
- Decking screws
- Weed membrane and gravel
- End-grain preservative
- 1
Plan the size and check the rules
~0.5 daysDecide the size and shape, check whether you need planning permission (height above ground, size, and boundary position), and measure so board lengths waste as little as possible.
- 2
Prepare the ground
~1 dayClear turf and plants, level the soil, lay weed-control membrane and cover with a layer of gravel. Give the ground a slight fall away from the house so water drains.
- 3
Build the frame
~1 dayLay out the outer frame in treated timber and check it is square by measuring the diagonals. Add joists inside at about 400mm centres, supported on pads or bearers so air can circulate underneath.
Tip: Equal diagonals means a perfect square. Check before you add joists.
- 4
Seal cut timber
~0.25 daysBrush preservative on every cut end of treated timber, because the cut ends are not protected and rot first.
- 5
Lay the first board and keep a gap
~1 dayFix the first board along the edge with a slight overhang. Leave a 5–8mm gap between boards for water to drain and the timber to expand, using spacers to keep it even.
- 6
Screw down the boards
~1 dayPre-drill and fix each board with two decking screws at every joist. Stagger joins along the board lines and cut the ends flush at the end.
- 7
Fit fascia, steps and balustrade
~1 dayCover the frame edges with fascia boards. Add steps if needed, and a strong balustrade on any edge with a drop of more than 600mm.
Balustrades must be strong enough to take a person leaning on them.
- 8
Treat the finished deck
~0.5 daysAfter a few weeks, brush on deck oil or stain to protect the boards. Re-apply every year or two.
Learn from others
Common mistakes to avoid
- Skipping the weed membrane, so weeds grow through the deck
- No gap between boards, so they swell and buckle
- Not allowing airflow underneath, which leads to rot
- Making the frame out of square
- Not checking the planning rules for a raised deck
Frequently asked questions
How much does it cost to build a deck?
For a typical 4 × 3 m ground-level deck in mid-range softwood, expect from around £610 doing it yourself to £990 with a contractor. A raised deck with posts and concrete footings, or composite boards, will cost more.
How much do deck boards cost?
Mid-range softwood deck boards cost around £28 per m². Budget pressure-treated softwood is cheaper; premium composite boards cost significantly more but need almost no maintenance.
Do I need planning permission or building regs for a deck?
Usually not, if it’s under 30cm high and covers less than half your garden — check your local rules if it’s higher, close to a boundary, or on a listed building. There’s no notifiable building-control work for a standard ground-level deck.
Can I build my own deck?
Yes — a ground-level deck is a very achievable DIY project: no notifiable work, and the skills involved (measuring, levelling, basic joinery) are learnable. A raised deck with deep footings is more physical work but still well within DIY reach for most people.
Ready to plan it?
Add this job to your renovation plan to get the order of work, who to book and a budget you can track.