How much does composite decking cost?

Most installers quote composite decking by the square metre, and a fitted price of £120–£250 per m² covers the large majority of UK garden decks.

At the lower end you are looking at hollow or basic solid boards on a treated timber frame, on a simple level site. The middle band, £160–£200 per m², is where most people land: solid or capped boards from a known brand, hidden fixings and a proper fascia around the edge. Above £200 per m² you are into premium capped boards with long warranties, aluminium joists, built-in lighting or awkward shapes.

Small decks cost more per m² than large ones, because the setting out, cutting and finishing take roughly the same time whatever the size. A 6m² deck can easily come in above £250 per m², while a 30m² deck on a flat lawn may come in near the bottom of the range.

On a typical composite deck, materials are roughly half to two thirds of the total.

The boards themselves run from about £45 per m² for budget hollow boards to £120 per m² or more for premium capped boards. Capped boards have a hard outer shell that resists staining and fading much better, and most are worth the extra if the deck gets full sun or heavy use.

The frame underneath is the other big material cost. Treated softwood joists are cheapest at around £20–£35 per m². Aluminium joists cost more, at roughly £40–£70 per m², but will not rot, which matters when the boards on top are expected to last 20 years or more.

Labour is usually £50–£90 per m², or a day rate of around £200–£300 per fitter. Composite needs closer joist spacing and more careful gapping than softwood because it expands and contracts with temperature, so it takes a little longer to lay.

On top of that come fascia boards, edge trims, hidden clips, screws, weed membrane and any base preparation such as gravel or concrete pads.

Softwood decking fitted usually costs £60–£120 per m², so composite is typically around double the price up front.

The difference is upkeep. Softwood needs cleaning and treating every year or two and boards can split, splinter or go slippery. Composite needs a wash with warm soapy water a couple of times a year and that is about it. Over 15 years, the treatment products and time spent on softwood close a good part of the gap.

Composite is not maintenance free, though. Cheaper uncapped boards can mark, fade and hold grease stains, and all composite gets hot in direct summer sun, darker colours especially.

If you plan to move within a few years, softwood is often the sensible choice. If you want the deck to look much the same in ten years without regular work, composite earns its price.

Board quality is the biggest single factor. Hollow, uncapped boards are cheapest; solid capped boards with a 25-year warranty cost much more.

The substructure. Even with composite boards, the frame is often timber, and that is the part that eventually fails. Aluminium or composite joists add cost but match the lifespan of the boards.

The site. A flat lawn with easy access is quickest. Sloping ground, raised decks needing posts set in concrete, or old patio to break out all add time. Most decks under 30cm high do not need planning permission, but raised decks, balconies and verandas often do, so check with your council if yours will be higher.

Shape and extras. Curves, picture-frame borders, steps, built-in planters, balustrades and lighting each add to the bill.

Access. If every board and bag of gravel has to go through the house, expect a higher labour price.

You can get a reasonable estimate before asking anyone.

1. Measure the length and width in metres and multiply to get the area. 2. Pick a per m² rate: around £140 for budget, £180 for mid-range, £230 for premium. 3. Multiply, then add steps, balustrades and old deck removal if needed.

Example: a 4m × 4m deck is 16m². At a mid-range £160–£200 per m² that is £2,560–£3,200. Add two steps at £80–£180 each and you are looking at roughly £2,700–£3,550 all in.

Add a margin if the ground slopes, the deck is raised, or access is awkward. Take a bit off if the base is already level and prepared.

On BidMyJob you can post the job with the size and a photo of the space, and local fitters bid, so you see real prices rather than a national average.

Keep the shape simple. Rectangles with boards running one way waste less material and take less time than angles and borders.

Design around board lengths. Composite boards usually come in fixed lengths such as 3.6m or 4.8m, and a deck sized to suit them produces fewer offcuts.

Do the clearing yourself. Lifting an old deck or clearing a lawn before the fitter arrives can save a day of labour.

Choose mid-range capped boards rather than the very top brand. The jump from budget to mid-range buys real durability; the jump from mid-range to premium is often more about colour and texture.

Get several quotes and check what each covers: substructure type, fixings, fascia, waste removal and warranty. Two quotes at the same headline price can be very different decks.