Cost calculator
Knock through cost calculator
Knocking two rooms into one sounds small and is a structural alteration. The steel is a modest part of the cost — design, propping, fire protection and making good are the rest.
Clear width of the new opening.
Broad trade availability keeps day rates near the national average.
Estimated range, ex VAT
£4,300 – £8,850
- Labour (typical)
- £3,600
- Materials (typical)
- £2,950
Guidance only. A real quotation depends on site conditions, specification and access — which is exactly what an independent review of your own quote will tell you.
What affects the cost
Load-bearing or not
A non-load-bearing stud wall is a day's work. A load-bearing wall needs an engineer, a beam and padstones.
Beam size and span
Wider openings need deeper, heavier beams — and above about 4m, craning or splicing.
Floors above
Supporting one floor is different from supporting two floors and a roof.
Services in the wall
Cables, pipes and radiators need diverting before demolition.
Making good
New plaster, flooring junction, skirting, ceiling line and decoration across both rooms.
Regional pricing differences
Materials cost roughly the same everywhere in the UK; labour does not. Use the region selector above to apply a local index — London and the South East typically run 15–30% above the national average, while the North East, Northern Ireland and Yorkshire sit below it.
Labour vs materials
Roughly 55% of this type of work is labour and 45% materials. Labour includes propping, breaking out, steel installation and making good. The beam itself is often under a fifth of the total.
Common hidden costs
- Structural engineer's calculations and building control fees, typically £600–£1,400 combined.
- Fire protection to the steel — required and frequently omitted from cheap quotes.
- Floor level differences between the two rooms revealed after the wall goes.
- Skip hire and dust protection in an occupied home.
How to save money
- Keep the opening under 3m where possible; beam cost rises steeply with span.
- Leave nibs or a downstand rather than a full flush opening — much less structural work.
- Combine with other work so plastering and decoration happen once.
- Ask for the engineer's beam schedule to be attached to the quotation.
Frequently asked questions
How much does it cost to knock down a wall?
£2,500–£6,500 for a load-bearing internal wall with steel and making good in 2026; £600–£1,200 for a non-load-bearing stud wall.
Do I need building regulations approval?
Yes for any load-bearing wall removal. A completion certificate matters at resale.
How do I know if a wall is load-bearing?
Only an engineer or experienced builder can confirm it. Direction of floor joists and position relative to walls above are the usual clues.
How long does it take?
Two to five days for the structural work, plus plastering and drying time.
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