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Is It Cheaper to Build a Deck or Pour Concrete? Concrete, Usually

A concrete slab costs less per square metre and lasts longer. Decking wins where the ground slopes, because levelling for concrete is the real expense.

By Zakaria 2 min read Save to Pinterest — opens Pinterest in a new tab
A timber deck with a white railing, a round table, chairs and a parasol
Photo: jjohnl, Pixabay Content License, via Pixabay
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Concrete, on flat ground — cheaper per square metre and far longer-lived. Decking wins on a slope, because levelling and retaining for a slab is the real expense, and a deck spans awkward ground on posts.

Where each one wins

This table answers the question on its own
Concrete slabTimber deck
Flat site, cost/m²LowerHigher
Sloping site, cost/m²Much higherLower
LifespanDecades15–25 years
MaintenanceCleaningStain every 2–3 years, board repairs
Over tree rootsPoor — disturbs themGood — spans on posts
Level with a back doorHardEasy
UnderfootHard, hot in sunWarmer, more forgiving
DrainageNeeds a fall designed inDrains through the gaps

The slab's cost is underground

Concrete itself is not expensive. What costs money is the level, compacted, free-draining sub-base underneath it — and on a gradient that means excavation, retaining and imported fill. That is the entire reason the comparison flips on a slope.

Over twenty years

Maintenance is where the gap widens. Concrete asks for cleaning and the occasional crack repair. Decking asks for cleaning, stain or sealant every two to three years, replacement of failed boards, and eventually attention to the frame and fixings — recurring for as long as it exists. Composite decking lasts longer than timber and costs more upfront, and still sits behind concrete on lifespan.

Choose decking when

  • The ground slopes or drains badly
  • You want a level surface at the height of the back door
  • There are tree roots you do not want to disturb
  • The weight of a slab would be a problem
  • Small children — warmer underfoot, softer to fall on

Rescuing a cracked slab

Decking laid on low-profile joists or adjustable pedestals over sound-but-cracked concrete is a common and good fix. Get two things right: a ventilation gap so air moves under the boards, and check the added height does not rise above a damp-proof course or foul a door.

On resale

Neither reliably beats the other. Condition decides it — a sound deck and a clean patio both read as usable space; a splintering deck and a cracked slab both read as a job the buyer inherits.

Common questions

Is it cheaper to build a deck or pour concrete?

On flat ground, concrete is almost always cheaper per square metre and it lasts far longer with less attention. The picture reverses as the ground slopes, because a slab has to sit on level, compacted, well-drained sub-base and creating that on a gradient means excavation, retaining and fill, which quickly costs more than the timber frame a deck would need. The honest rule is that concrete wins on flat sites and decking wins on awkward ones.

Which lasts longer, decking or a concrete patio?

Concrete, by a wide margin. A properly laid slab lasts decades with occasional cleaning and the odd repair to a crack, while timber decking typically needs staining or sealing every two to three years and replacement of boards after fifteen to twenty-five years depending on the timber and the climate. Composite decking lasts longer than timber and costs more upfront, but still sits behind concrete on lifespan.

What is the real cost difference over time?

Maintenance is where it shows. Concrete asks for cleaning and very little else. Timber decking needs cleaning, periodic stain or sealant, replacement of failed boards and eventually attention to the frame and fixings, and those costs recur for as long as the deck exists. Over a twenty-year horizon the gap between the two widens considerably in concrete's favour, even where the initial prices were close.

When is decking the better choice?

On a slope, over uneven or poorly draining ground, where you want a level surface at the height of a back door, over tree roots you do not want to disturb, and where the weight of a slab would be a problem. A deck is built on posts and can span awkward ground cheaply, which is exactly the situation that makes concrete expensive. It is also warmer underfoot and more forgiving to fall on, which matters with small children.

Which adds more value to a house?

Neither reliably outperforms the other, and the condition matters far more than the material. A well-maintained patio or a sound deck both read as usable outdoor space, while a cracked slab or a grey splintering deck both read as a job the buyer will inherit. What does add value is the space being genuinely usable — level, large enough for a table, and connected sensibly to the house.

Can you put decking on top of an old concrete patio?

Yes, and it is a common way to rescue a cracked but structurally sound slab. Decking is laid on low-profile joists or adjustable pedestals over the concrete, which keeps the timber off the wet surface and lets water drain beneath. The two things to get right are a ventilation gap so air moves under the boards, and checking that the added height does not bring the deck above a damp-proof course or block a door.

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