Composite Decking Bradford
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For tired patios and concrete

Decking over an old patio

A patio that has sunk, cracked or turned black is one of the most common reasons people look at decking. Often the old slabs can stay where they are and the deck goes straight over them on adjustable pedestals.

Because there is little or no groundwork, a deck over a sound patio usually lands in the lower half of the composite range: roughly £100 to £150 per square metre fitted.

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Before

door silltilted, stained slabssound old base

After

deck below the sillpedestals, no digging
An old patio with tilted, stained slabs. The deck goes on adjustable pedestals on top, with no digging, and finishes just below the door sill.

When you can deck straight over a patio

  1. The base is sound

    Slabs can be uneven or stained, but not breaking up or rocking badly. Pedestals need something firm to stand on.

  2. There is height to spare

    Pedestals plus joists and boards add about 65 to 100 mm at the lowest. The finished deck should stay around 150 mm below the door sill, so measure first.

  3. Water can still get away

    The patio should already shed rain away from the house. The deck lets water straight through to it, so a patio that floods will still flood.

  4. Air can move underneath

    Leave gaps around the edges, behind fascias, so the underside dries out. It keeps the frame healthy and stops smells.

  5. Drains and covers stay reachable

    Any manhole, gully or rodding eye under the deck needs a lift-out panel above it.

  6. Air bricks stay clear

    A deck must not cover the air bricks that ventilate a suspended timber floor. If it would, the deck has to step down or the bricks need extending.

What decking over a patio costs

Composite boards on adjustable pedestals or a low frame, fitted over an existing sound base.

Price your own size in the calculator

JobTypical price
Small patio, 9 m²
3 × 3 m		£900 to £1,400
Medium patio, 15 m²
5 × 3 m		£1,500 to £2,300
Large patio, 24 m²
6 × 4 m		£2,400 to £3,600
If the slabs must come up
Lifting and disposal first		£150 to £600 extra
Where these figures come from

Typical UK fitted prices from published price lists we reviewed, October 2026. National figures, not Bradford-specific, and some lists do not say whether VAT is included. A guide, not a quote.

Pedestals, a low frame or lifting the slabs

There are three ways to do it, and the right one comes down to the height you have and the state of the slabs.

  • Adjustable pedestals. Plastic or rubber supports, screwed up or down to take out the dips, carrying the joists. Quick, no digging, and easy to adjust if anything settles later.
  • A low timber or aluminium frame on packers. Used when the patio is fairly flat. It can be slightly lower than pedestals, which helps when the door sill is close.
  • Lifting the patio first. When there is not enough height, the slabs are broken, or water sits on the surface. The deck then goes on a frame on the ground, and the job looks more like a new build.

Concrete bases

Plain concrete, such as an old garage base or a cast slab behind a back door, makes an excellent base for a composite deck as long as it falls slightly away from the house. Cracks are not usually a problem unless one side has dropped.

What it saves, and what it does not

Leaving the patio in place saves the labour of lifting it and the cost of a skip, which is a real saving when all the waste would have to go back through the house. It also keeps weeds down for good, because the old slabs act as a membrane.

It does not save on boards or fixings. A deck over a patio uses exactly as many boards as one on the ground, and the pedestals are an extra line on the quote. Expect the saving to be in the groundwork, not the materials.

Deck on topLift patio first
GroundworkNoneLift, level, membrane
Waste to removeNoneUsually a skip
Height above slabsAbout 65 to 100 mmCan go lower
Days on site, 15 m²About 2About 3 to 4

Planning

Laying a deck over an existing patio does not normally need planning permission, because it adds only a few centimetres of height and stays well under the 30 cm limit for platforms. The usual exceptions apply for listed buildings and some conservation areas.

Questions we get asked

Can you put composite decking on top of a patio?

Yes, as long as the patio is sound, drains away from the house and there is enough height below the door sill for pedestals, joists and boards.

How much height does decking over a patio add?

Usually about 65 to 100 mm at the lowest point, more where pedestals take out dips. Measure from the slabs to the door sill before you choose boards.

Is it cheaper to deck over a patio?

Usually, because there is no lifting, levelling or skip. Expect roughly £100 to £150 per square metre for composite over a sound base.

Can decking go directly on concrete?

Not board to slab. The boards need joists underneath, on pedestals or packers, so water can drain and air can move.

Will decking over a patio rot?

Composite boards do not rot. Use aluminium joists or treated timber rated for ground contact, keep the edges ventilated and the frame will last.

Tell us about your patio

Three quick steps. A rough idea of the garden is plenty: the slope, the size, what you'd like to use it for.

Free to use. We are an introduction service: we find an independent local decking installer for the job and tell you who they are before anyone contacts you.

Step 1 of 3

Your postcode
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