How Much Do Structural Alterations Cost in London?
Real 2025 figures from completed London projects. Wall removals from £1,200 for non-structural, £3,500+ for load-bearing. Steel beams, chimney breasts, structural openings — here's what it actually costs and why.
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Quick Cost Overview
* London market rates, Q3 2025. Excludes VAT, structural engineer fee (£500–£1,500 extra), and second-fix finishes unless stated.
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What Affects the Cost of Structural Alterations?
Load-bearing or not
This is the single biggest cost variable. A non-structural partition wall costs a fraction of a load-bearing wall removal. You need a structural engineer to confirm which is which — never assume.
What's above the wall
A wall supporting a first floor requires a bigger beam than one supporting only roof load. Multiple floors above mean larger, more expensive steelwork and more complex temporary propping.
Beam span and size
Longer spans require larger steel sections — an RSJ spanning 3m costs significantly less than one spanning 6m+. Beam size is dictated by structural engineer calculations, not contractor preference.
Access and site conditions
Restricted access, narrow passageways, or needing to bring steelwork through upper floors all add labour time and cost. Ground floor rear openings are typically the most straightforward.
Party wall matters
If the wall is shared with a neighbour, you may need a Party Wall Agreement before work can begin. This adds time (minimum two months for the notice period) and potentially surveyor fees on both sides.
Making good and finishes
Structural work exposes floors, walls and ceilings that then need making good. If you're also having plaster, skirting, and decoration done, price these separately — they're not usually included in a structural-only quote.
Structural Alterations Price Table — London 2025
| Work Type | Low | High |
|---|---|---|
| Non-load-bearing wall removal | £1,200 | £2,500 |
| Load-bearing wall removal + RSJ | £3,500 | £8,000 |
| Steel beam (RSJ) supply + install | £2,500 | £6,000 |
| Chimney breast removal (per floor) | £1,800 | £4,500 |
| Full chimney removal (ground to roof) | £4,000 | £9,000 |
| Structural opening for bifold/sliding doors | £4,500 | £10,000 |
| Staircase removal and replacement | £5,000 | £18,000 |
| Structural engineer fee | £500 | £1,500 |
All figures are London market rates, Q3 2025. Excludes VAT. Structural engineer fee not included unless stated. Second-fix finishes (plastering, decorating) are separate.
Load-Bearing vs Non-Load-Bearing Walls: Why It Matters So Much
The distinction between a structural (load-bearing) wall and a partition wall is the most important factor in the cost of any wall removal. Get this wrong and you risk serious structural damage.
Non-Load-Bearing Partition Wall
- ✓No structural engineer required
- ✓No steel beam or padstones needed
- ✓Typically 1–2 days of work
- ✓Cost: £1,200–£2,500 in London
- →Still needs Building Regulations if electrical or structural work follows
Load-Bearing Wall
- !Structural engineer required — mandatory
- !Steel beam (RSJ) must be installed
- !Temporary propping required during works
- !Building Control inspection required
- →Cost: £3,500–£8,000+ in London, depending on span
Steel Beam (RSJ) Installation Costs in London
When a load-bearing wall is removed, a steel beam — typically a Rolled Steel Joist (RSJ) or Universal Beam (UB) — is installed to carry the load previously taken by the wall. The beam size is dictated by structural calculations.
Costs include supply and installation of steel, padstones, temporary propping, and basic making good. Excludes structural engineer fee (typically £500–£1,500 additional) and decorative finishes.
Chimney Breast Removal Costs in London
Chimney breast removal is one of the most common structural alteration requests in London's Victorian and Edwardian terraces. The complexity — and cost — depends on which floors are involved and whether the property is mid-terrace (shared flue).
Ground Floor Only (chimney retained above)
- • RSJ required to support chimney above
- • Debris removal included
- • Making good to walls, floor, and ceiling
- • Structural engineer sign-off required
Full Removal (all floors + stack)
- • Ground + first floor + stack
- • Roof patching and weatherproofing
- • Making good on all floors
- • Party wall considerations if terraced
What's Typically Included — and What Isn't
✓Usually included in a structural package
- ✓Temporary propping and protection
- ✓Demolition of wall/chimney breast
- ✓Debris removal and disposal
- ✓Steel beam supply and installation
- ✓Padstones (concrete or engineering brick)
- ✓Basic making good (blocking up, patching)
- ✓Building Control notification (your contractor should handle this)
✗Usually excluded
- ✗Structural engineer fee (£500–£1,500)
- ✗Skim plastering of affected walls
- ✗Decoration (painting and decorating)
- ✗Flooring repair or replacement
- ✗Electrical re-routing through affected walls
- ✗Party wall surveyor fees (if applicable)
- ✗Fire stopping, cavity barriers (if required by Building Regs)
Compliance: What You Actually Need
Structural engineer
Always required for load-bearing workThey provide calculations specifying beam size, padstone requirements, and temporary propping design. Without this, Building Control will not sign off the work. Their fee is separate from the contractor and typically costs £500–£1,500.
Building Regulations
Mandatory for all structural workYou must notify your local authority (or use an approved inspector) before structural work begins. A Building Control officer will inspect the work at key stages and issue a completion certificate. Without this, you may have problems when you come to sell the property.
Planning permission
Not normally required for internal structural workInternal alterations — wall removals, steel beams, chimney breasts — do not usually require planning permission. Exceptions include listed buildings (where Listed Building Consent is needed) and some conservation areas. External changes connected to structural works may still need planning.
Party wall agreement
May be required if work is near shared boundaryIf you share a wall with a neighbour and the structural work is within 3–6 metres of it, the Party Wall etc. Act 1996 may apply. You must serve notice at least two months before work starts. Your neighbour can agree in writing or appoint a surveyor.