Underpinning cost: what a proper quote should include

Underpinning a UK home typically costs £9,750 – £16,300, with a typical job landing around £12,500 for the traditional mass-concrete method on a standard 8-section run. Basic jobs start from £9,450; large or difficult ones with premium methods reach £16,900. Beyond that headline number, the thing that catches homeowners out isn't the underpinning itself — it's everything that has to happen before and after it, which a bare quote often leaves out.

Why quotes for the same job vary so much

Underpinning prices swing more than most home improvement jobs because so much of the cost depends on what's underground and what's above it, not just the length of wall being underpinned. Two houses with an identical crack in the brickwork can need very different solutions: one might need a short run of traditional mass-concrete underpinning, the other a mini-piled system because of tree roots, made ground, or a nearby drain. A quote that doesn't say which method it's pricing, and why, is one to question.

What a full underpinning quote should cover

A proper quote is really pricing several separate pieces of work, not just "underpinning." Ask for each of these to be itemised or at least confirmed as included:

• Structural engineer's report and design. Someone has to establish the cause of movement (subsidence, tree roots, drains, poor original foundations) and specify the method and depth. This is normally a separate fee, paid before building work starts, and it's easy for it to get lost if you're only shown a builder's headline figure.
• Site investigation. Trial pits or boreholes to check soil type and depth to a stable bearing layer. Skipping this is how quotes come in low and then balloon once work starts and the ground turns out to be worse than assumed.
• The excavation and underpinning itself. Dug and concreted in short sections (never the whole wall at once, for stability), or installed as mini-piles with a needle beam where access or ground conditions rule out traditional digging.
• Making good. Reinstating floors, skirting, plaster and external ground level disturbed by the dig. This is often the difference between a basic and a mid-range price on paper — it's easy to quote the concrete and forget the plasterer.
• Building control sign-off. Underpinning is structural work and needs building regulations approval; a competent contractor will have this in the price and timeline, not as a surprise add-on.
• Access and spoil removal. Machine access, propping neighbouring structures, and removing excavated soil can matter as much as the underpinning method if the property is terraced, has no side access, or sits close to a boundary.

What pushes a quote toward the top of the range

A handful of situations reliably move a job from the low end of Underpinning toward the £16,900 end:

• Restricted access. Terraced or semi-detached houses with no side passage often need hand-dug sections and manual spoil removal instead of machine access, which adds labour time for the same length of wall.
• Depth to good ground. If trial pits show the stable bearing strata is deep, either the traditional dig gets deeper (more concrete, more propping) or the job moves to mini-piling, which costs more per metre but disturbs less ground.
• Number of separate sections. Underpinning is priced and built in short bays for safety, so a long or L-shaped run of wall costs more than the same total length done in one place.
• Party walls. Where the underpinned wall is shared with a neighbour, you'll also be paying for a party wall agreement and possibly a party wall surveyor, which sits outside the builder's price.
• Knock-on damp or crack repair. Underpinning stops movement; it doesn't fix the cracks or damp the movement caused. Expect a separate allowance for crack stitching, replastering, or in some cases

Material	Typical	Usual range	Lifespan
Chemical DPC injection	£2,500	£1,950 – £3,250	20-30 years
Penetrating damp: repointing and internal replaster	£3,950	£3,100 – £5,150	25-40 years
Cellar tanking (cementitious, full height)	£5,650	£4,400 – £7,300	25+ years

if the subsidence let moisture in.

How we calculate our figures

Our underpinning estimates start from labour hours for excavation, formwork, concreting and making good, multiplied by local trade rates, plus materials and plant hire, then checked against market data and real contractor quotes. The default in our model is an 8-section job; a short single-crack repair or a long wall needing full perimeter underpinning will move well outside the typical range, which is exactly why a site-specific quote from a structural engineer matters more here than on most home improvement jobs.

Getting quotes you can compare

Because underpinning quotes hide so much in the assumptions (method, depth, access, making good), get at least two contractors to quote against the same engineer's specification rather than their own assessment of the problem — otherwise you're comparing different jobs, not different prices. If a quote arrives well below or above what you expected, our "is my quote fair" tool is a quick way to sanity-check it against local rates before you commit. For related work that often comes up alongside subsidence repair, see our guides to Damp proofing and Rendering.