Key Takeaways
- Removing a load-bearing wall and installing an RSJ typically costs £2,500 to £6,500+ all in, with a standard kitchen opening landing at £2,500 to £3,400 (Checkatrade, MyBuilder and MyJobQuote, 2026).
- Steel is the cheap part. Supply only is £70 to £120 per metre; supplied and installed it is £300 to £600 per metre.
- A structural engineer is always required for calculations, so budget £300 to £700 in 2026.
- The work needs Building Regulations approval and a completion certificate, not planning permission.
- If the beam bears into a shared wall, serve a party wall notice two months before work starts.
- Allow 4 to 8 weeks end to end: 3 to 5 days of that is site work.
Taking out a load-bearing wall turns dark, boxy rooms into one bright space, and it is the change most London homeowners ask us about first. This guide covers what it costs in 2026, how to tell whether a wall is load-bearing, the building regulations and party wall rules that apply, and how the job actually runs.
How much does it cost to remove a load-bearing wall?
Removing a load-bearing wall and installing a steel beam typically costs £2,500 to £6,500 or more. A standard kitchen wall opening with clear access and a single beam sits at £2,500 to £3,400, while wide openings needing twin beams or a goalpost frame reach £7,500. The steel itself is rarely the biggest line on the invoice: labour, propping, building control and making good usually account for around two thirds of the total.
| Item | Typical cost | Notes |
|---|---|---|
| Structural engineer's calculations | £300 to £700 | Beam sizing, bearings, padstones, building control pack |
| Steel beam, supply only | £70 to £120 per metre | Varies with section depth and weight |
| Steel supplied and installed | £300 to £600 per metre | Labour, lifting, padstones and fixings |
| Building control application | £300 to £900 | London boroughs sit at the top of the range |
| Temporary propping and skip | £400 to £800 | Add £30 to £80 if the skip goes on the road |
| Making good: plaster, fire boxing, decoration | £600 to £1,500 | Per opening, flooring excluded |
| Simple single-beam knock-through, all in | £2,500 to £3,400 | 3 m opening, ground floor, clear access |
| Wide opening, twin beam or goalpost frame | £4,000 to £7,500 | Posts down to new pad foundations add cost |
Three things push a London job to the upper end. Access: a 5 m beam that will not come through the front door has to be craned in, or split and bolted together on site. Load path: if the masonry under the beam ends cannot take the new point loads, you need steel posts and pad foundations rather than padstones. Services: the wall often carries cables, pipework or the soil stack, and diverting those is a separate trade. See RSJ installation in London.
What is an RSJ?
An RSJ, or rolled steel joist, is the steel beam that carries the load once a supporting wall is removed. The weight the wall was holding, whether floors, walls or roof above, has to be transferred into a beam and back down through new supports at each end. You will also see the terms UB (universal beam) and UC (universal column), which are the modern designations for the sections actually specified today.
Sizing that beam is what you pay a structural engineer £300 to £700 for. They check the joist span and direction, work out the dead and imposed loads landing on the wall, and pick a section that satisfies both strength and deflection. Deflection usually governs a domestic beam: steel strong enough not to fail can still sag enough to crack the wall above. You get back a calculation pack giving the beam size, bearing length, padstone detail and any restraint notes, in a format building control will accept. Allow one to two weeks.
How to tell if a wall is load-bearing
You should never assume, but there are strong indicators. A wall is more likely to be load-bearing if it:
- Runs at right angles (perpendicular) to the floor joists above.
- Sits directly above another wall, beam or steel on the floor below.
- Forms part of an external wall of the house.
- Is built in solid masonry (brick or block) and is noticeably thicker than a stud partition.
- Supports the ends of joists, a staircase or a roof structure.
By contrast, a thin stud partition that runs parallel to the joists is often non-load-bearing, though it can still carry services or bracing. The only safe way to be certain is to have a structural engineer or experienced builder inspect it, ideally lifting a floorboard above to check the joist direction.
Do you need building regulations approval?
Yes, always. Removing a load-bearing wall requires Building Regulations approval, regardless of whether you need planning permission, and you usually do not for internal structural work. You can go one of two routes:
- Full plans application. The engineer's calculations and drawings are checked and approved before anyone lifts a hammer. Slower to start, but you get written approval and no arguments on site. This is the route we use for structural openings.
- Building notice. You give notice and the inspector approves the work as it is carried out. Quicker to start, but nothing is agreed in advance, so any disagreement about the beam happens with your ceiling already propped.
Either route can be run through your local authority or through a registered building control approver. Fees for domestic alterations run roughly £300 to £900, with London boroughs at the top end. Expect at least two site visits: one with the steel and its bearings exposed, and one at completion, which is what triggers the certificate.
Beam types, padstones and goalposts
The engineer's design determines not just the beam but how it is supported. A few terms worth knowing:
- Padstones: high-strength concrete or steel blocks that spread the beam's load into the masonry at each end. Skipping or undersizing these is a common cause of cracking.
- Goalpost frame: where the wall below cannot take the load, vertical steel posts are bolted to the beam to form a goalpost, carrying the load to the foundations. This is common in wider openings and side-return extensions.
- Single vs double beams: wider spans or heavier loads may need two beams bolted together, which increases cost and the lifting equipment required.
- Fire protection: bare steel loses strength fast in a fire, so a domestic beam is normally boxed in with fire-rated plasterboard, or coated in intumescent paint, to give at least 30 minutes' resistance under Approved Document B. If you want the steel left exposed for the look, agree it with building control before it is installed, not after.
Do you need a party wall agreement?
Probably, if the beam bears into a shared wall. Cutting a pocket into a party wall to seat a steel beam is notifiable work under the Party Wall etc. Act 1996, so you must serve a party structure notice on every affected neighbour at least two months before work starts. In London's terraces and semis that catches most knock-throughs.
Your neighbour then has 14 days to reply, and silence counts as dissent, not consent. If they consent in writing, that is the end of it and it costs you nothing. If they dissent, surveyors are appointed and a party wall award is drawn up, which in 2026 typically runs £900 to £2,000 per surveyor, paid by you as the building owner, and adds three to six weeks to the programme. Serve early, and speak to the neighbour before the formal letter lands. Our Party Wall Act guide and our notes on dealing with neighbours during building work cover the process in full.
Fee ranges from Pine, BookaBuilderUK and Wimbledon Surveyors 2026 party wall fee guides; notice periods from the gov.uk Party Wall etc. Act 1996 explanatory booklet.The step-by-step process
Allow 4 to 8 weeks from first call to a finished wall, longer if a party wall award is involved. Calculations take one to two weeks, steel is usually fabricated and delivered within a week of order, and the site work itself is 3 to 5 days for a single beam. The sequence below is strictly ordered, because the structure above is temporarily unsupported partway through.
- Survey & engineer's calculations, where the beam is sized and specified.
- Building control & party wall notices arranged in advance.
- Temporary propping installed to support the load safely.
- Wall removed and opening cut for the beam bearings.
- Steel beam seated on padstones and bolted or welded as specified.
- Building Control inspection before the steel is encased.
- Making good, including plastering, fire protection and finishing.
What goes wrong, and how to avoid it
Nearly every failed opening we get called to look at comes down to one of five things.
- No calculations. A beam sized by eye may well hold the floor up and still deflect enough to crack the wall above and jam the bedroom doors.
- Undersized or missing padstones. The beam ends concentrate the whole load into a few bricks. Without a properly specified padstone the masonry crushes and stepped cracking appears within months.
- Props struck too early. Padstone mortar and any packing need to cure and take up before the props come out, or the wall above settles onto the beam and cracks.
- Steel boarded over before inspection. Cover the beam and its bearings before building control has seen them and you may be opening the work back up at your own cost.
- Services discovered mid-demolition. Old walls hide cables, pipes and sometimes the soil stack. These need tracing and diverting before the wall comes down, not during.
Some hairline cracking in the plaster above a new opening is normal as the structure takes up. Cracking that keeps widening, runs diagonally from the beam ends, or arrives alongside doors that suddenly stick is not. Our guide to cracks in walls and when to worry explains how to tell the difference.
Can you remove a load-bearing wall yourself?
No. Without engineer's calculations, temporary support and building control sign-off, taking out a load-bearing wall risks collapse, cracking and serious injury, and it breaches Building Regulations. GS Renovation carries out load-bearing wall removal and RSJ installation across all of London. Related reading: knocking two rooms into one, chimney breast removal and our kitchen renovation cost guide. For a free quote, get in touch or call 07472 424 226.