The structural steel behind every wall removal, opening and loft conversion — calculated by our in-house engineers, supplied, propped, seated on engineered padstones and signed off by Building Control. Whether you need a single beam for a knock-through or a frame for an extension, designed and installed under one fixed-price contract, with the Party Wall process handled.
Almost every project that opens up a London home depends on a steel beam. Take out a wall to create open-plan living, form an opening for bi-fold doors, remove a chimney breast, or convert a loft, and something has to carry the load that the masonry used to. That something is an engineered steel beam — the single most important component in the whole job, and the one you never see once it is done.
This page is for steel beam and RSJ installation — the structural steel that makes openings possible, calculated and installed properly. As a design-and-build contractor with in-house structural engineers, we can take it from scratch — survey, calculation, supply and installation under one fixed-price contract — or install a beam to your own engineer's design. Either way, we handle the propping, the padstones, the lift, the seating, the fire protection, the Building Control sign-off and the Party Wall process. If the beam is part of a larger job, it sits within our knock-through, open-plan, loft or extension work; here it is the focus.
RSJ is the term everyone uses — rolled steel joist — though modern steel is more correctly a universal beam (UB) or universal column (UC). What matters is that it is sized for the exact span and load it carries, calculated to the Eurocodes by a qualified engineer, and supported correctly at each end. A beam that is undersized, badly bearing, or installed without checking that the walls below can carry the load to the foundations, is not a saving — it is a structural risk that shows up as cracked ceilings, sticking doors, or worse.
The difference between a sound installation and a dangerous one is almost all in the things you cannot see: the calculation, the temporary propping that holds the house up while the wall comes out, the padstones that spread the load into the masonry, and the inspection before everything is concealed. These are exactly the steps that get skipped on a cheap job, and exactly where we focus.
We design and install structural steel across NW3, NW8, NW1, NW11, N6, W1 and SW London — single beams for knock-throughs, multiple beams for full open-plan ground floors, goalpost frames for extensions, and the steelwork that makes loft conversions possible.
Steel does the structural heavy lifting across most home alterations. These are the six situations we install it for most.
A single beam carrying the floor or wall above when a load-bearing wall is removed for a knock-through. The everyday job — sized, propped, seated and signed off to open one room into another.
Several beams — sometimes interconnected — removing multiple walls to create a single open-plan ground floor. Careful sequencing keeps the structure supported as each wall comes out.
Beams carrying the new loft floor and supporting the roof where dormers or a mansard alter the structure — the steelwork that makes a habitable loft possible, often manoeuvred up through the house.
A beam carrying the chimney breast and stack above when a lower breast is removed — the stronger alternative to gallows brackets, and often the method Building Control prefers. See our chimney breast removal page.
A portal or “goalpost” frame — two columns and a beam — opening up the entire rear of the house into an extension for full-width glazing and bi-fold doors. The structural backbone of a modern rear extension.
Beams and flitch plates strengthening floors for heavy loads — a kitchen island, a large bath, a new opening — or supporting a balcony or terrace. The structural reinforcement that lets a floor take what is asked of it.
Installing a beam safely is a precise structural sequence. Every element below is delivered and warranted under one fixed-price agreement.
Our MIStructE engineers assess the load above, size the beam to the span and load, design the connections and padstones, and check the supporting walls carry the load to the foundations. Full calculations issued for Building Control.
The correct universal beam or column supplied from audited UK steelyards, cut to length, drilled and prepared — or fabricated as a frame where the project needs columns and connections, not just a single beam.
Engineered propping and needling installed to carry the structure safely while the masonry is removed and the beam positioned — the work that keeps the house standing and everyone safe during the lift.
Pre-cast concrete padstones to calculation spread the beam's load into the supporting masonry, with the walls checked and strengthened where the bearing demands it — the detail that stops a beam crushing into a wall over time.
The beam lifted into position — by hand, lifting gear or crane as access dictates — seated level on its padstones, connected, and the props struck only once it is fully bearing. Tolerances checked throughout.
Bolted or welded connections to the engineer's detail, and splices where a single beam length cannot be carried into a terraced house — engineered joints that perform as a continuous member.
The beam protected to the required fire rating — usually boxed in fire-rated plasterboard, or with intumescent paint where the steel is left exposed as a feature — to satisfy Building Regulations.
Full Building Regulations submission with the structural calculations, the steel and bearings inspected before they are concealed, and a completion certificate issued — the document that protects you and matters at resale.
Where the beam bears into a party wall, notices served, schedules of condition prepared and the award agreed through our sister surveying company — the step most often overlooked on a steel job.
The opening squared, the beam encased or detailed flush, and the surrounding walls and ceiling re-plastered — so the structure disappears into a clean opening rather than a patched-up gap.
The lift planned to the access — hand-balling, gantry, or crane — with protection to floors and stairs and a method statement for the operation. Tight terraced access is routine for us, not a surprise.
A snagging walk, a 12-month defects period and a 10-year workmanship warranty on the works.
A steel installation is judged entirely on what you cannot see. These are the six things our engineers resolve before and during the work.
Establishing exactly what the wall carries — floors, walls, roof, point loads — and how that load travels down to the foundations. Everything else depends on getting this right.
The beam calculated to the Eurocodes for strength and deflection, so it neither fails nor visibly sags. The right section for the span — not a guess from a rule of thumb.
Calculated padstones spreading the load into the masonry, with the supporting walls checked — the detail that stops the beam punching into the wall over years.
Engineered temporary support carrying the structure while the wall is removed. The wall never comes out before the propping is proven — the moment safety is won or lost.
The steel protected to the required fire resistance — boxed or intumescent-painted — so the opening meets Building Regulations as well as carrying the load.
Building Control inspecting the steel and bearings before they are plastered over — and a completion certificate. The proof, for you and a future buyer, that it was done right.
A steel installation is a controlled structural sequence. Here is how we run it.
We look at the opening you want to create, discuss the result and your budget. No charge, no obligation.
A survey establishing what the wall carries, the load path and the access — the basis for the calculations and a firm price.
The beam, connections and padstones calculated by our MIStructE engineers, with the beam detail (flush or downstand) shown to you.
Building Regulations submission and, where a shared wall is affected, Party Wall notices served and the award agreed.
The steel cut, drilled and prepared — or the frame fabricated — and delivered to site, with the lift and access planned.
Temporary propping, masonry removed, beam lifted in and seated on padstones, props struck. Building Control inspects the steel and bearings.
The beam fire-protected, the opening made good and plastered, then a snagging walk and the completion certificate.
A 12-month defects period and a 10-year workmanship warranty on the works.
What a steel installation costs depends on the span, the load, the access and the number of beams. Here is how the levels differ.
For a representative single load-bearing wall beam at around £6,500 supplied and installed, here is the honest breakdown.
For those who want the technical picture, here is what the steelwork involves.
Installing a structural beam is always a Building Regulations matter, and very often a Party Wall one too.
Any structural steel beam in a home requires Building Regulations approval. The design must be calculated and submitted, the steel and its bearings inspected before they are concealed, and a completion certificate issued. This is not optional paperwork — it is the legal and safety framework for altering the structure of your house, and the certificate is what your insurer and a future buyer's surveyor will expect to see. Installing a beam without it is one of the most common and serious issues flagged in home-buyer surveys.
Where the beam bears into a party wall — the wall shared with an attached neighbour — or where you cut a bearing pocket into it, the Party Wall etc. Act 1996 applies. Notice must be served on the neighbour, a schedule of condition prepared, and an award agreed before work starts. Because most openings in London's terraced and semi-detached homes involve a party wall, this is the norm rather than the exception, and we manage it through our sister surveying company.
Planning permission is generally not required for internal structural steel (unless the property is Listed, where internal alterations need Listed Building Consent, or the steel is part of an extension). We confirm exactly what your project needs at survey and manage every approval. For an early budget, use the cost calculator; for the wider job the beam supports, see knock-through, open-plan living or structural works.
A representative programme for supplying and installing one beam for a wall opening. Yours will differ by scope, but this is the sequence.
Structural steel is no place for shortcuts. Here is what makes ours safe, certified and clean.
Our own MIStructE engineers size the steel — design and build under one roof, so the beam is calculated, not guessed.
We can run the whole job, or install to your engineer's design — whichever suits your project.
Engineered temporary works carry the house safely while the wall comes out — never a shortcut on the most critical moment.
We design steel to sit flush wherever the structure allows — no clumsy unplanned downstand across your ceiling.
Submission, inspection, completion certificate and the Party Wall award all managed for you.
Manoeuvring beams into terraced and basement spaces is everyday work for us, planned not improvised.
Professional indemnity and public liability at £10M, well above industry standard.
An insurance-backed workmanship warranty protecting the structural work long after completion.
A steel beam is usually part of a wider project. Start here, or speak to us about the whole job.
Removing a load-bearing wall — the most common reason for a beam.
Multiple beams opening up the whole ground floor.
A beam supporting the breast and stack above a removal.
The steelwork carrying the new floor and supporting the roof.
Goalpost frames opening the rear of the house into an extension.
Our full structural capability — beams, openings, underpinning and more.
The calculations and detailing behind every beam, by MIStructE engineers.
Strengthening foundations where loads or ground conditions require it.
Comparable projects with real structural openings. Browse the case-study hub, and for survey-led due diligence before you commit, see surveying support.
Load-bearing walls removed on engineered steel to open up the ground floor.
View case study →Roof reconstruction and structural steel works within a listed duplex.
View case study →Double-storey extension and loft conversion with substantial steelwork.
View case study →Our full structural capability across openings, beams and foundations.
Explore →“I would like to thank Ross and his team for their consistent commitment to quality and their unerring reliability. They delivered our property to specification and on time, proving to be an extremely effective, experienced, and proactive contractor.”
“We have worked with Ross and his company many times. They are extremely professional and hardworking individuals who can work under any circumstances. There was no variation to the works.”
Book a no-obligation consultation at our Finchley Road design studio or in your home. The first meeting is free, lasts 60–90 minutes, and concludes with an honest indication of feasibility, programme and budget band. No salespeople. No pressure.
Site visit · feasibility assessment · outline cost estimate · programme indication. No obligation. Saturday appointments available.