What is an RSJ? Steel beams explained for homeowners
RSJ, UB, UC, PFC, flitch beam — what the terms mean, which steel beam is used where, and what an RSJ costs supplied and fitted in 2026.
Service
Steel beam & RSJ installation in Cheshire
We supply and install steel beams (usually called RSJs), columns and goalpost frames to the structural engineer's specification — for internal knock-throughs, rear extensions, bifold and sliding door openings, and loft conversions.
Steel arrives cut to length, is lifted into position, seated on padstones or bolted to columns, then packed tight to the structure above. Building control inspect the bearings before the steel is boxed in.
What’s included
- Universal beams (UB), universal columns (UC), channels (PFC) and flitch plates to specification
- Goalpost and box frames for large rear openings
- Bolted connections, end plates and cleats
- Padstones and pad foundations where specified
- Beams in bolted sections where access is tight (if the design allows)
- Supply-and-fit for homeowners, fit-only for builders
Worth knowing before you book anyone
RSJ or UB?
“RSJ” has become the everyday word for any steel beam. Most modern steels are universal beams (UBs) with parallel flanges. Your engineer specifies the exact section and grade.
Getting the steel in
Long beams need a clear route into the house. Where access is tight, the engineer can design a beam made in sections and bolted together in place.
Fire protection
Steel in homes usually needs fire protection — typically plasterboard boxing or intumescent paint — to satisfy building control.
Steel beam & RSJ installation: your questions answered
Do you supply the steel as well as fitting it?
Yes. We can supply and fit, or fit steel that you or your builder have ordered, provided it matches the engineer's specification.
How do you get a long steel beam into a house?
Usually through a door, window or rear opening. For tight access the engineer can specify a beam made in sections and bolted together in place.
What is a goalpost frame?
Two steel columns and a beam forming a frame. It is used where a wall is removed down to the floor — such as a wide opening into a rear extension — so the load goes straight down to the foundations.
How long does a steel beam installation take?
A single beam in an internal wall is typically installed in a day or two. Goalpost frames and multi-beam jobs take two to four days, plus making good.
Related guides
How long does a steel beam installation take, start to finish?
Timeline for a steel beam installation: survey to engineer's calcs to approval to install day. What happens when, and what can stretch the programme.
The Party Wall Act and steel beams: when you must tell your neighbour
Cutting a beam into a shared wall in a semi or terrace? The Party Wall etc. Act 1996 requires notice to your neighbour. What notice involves, timelines and costs.
Where we do this
Steel beam & RSJ installation across Knutsford, Wilmslow, Macclesfield, Altrincham, Sale, Stockport, Didsbury & South Manchester, Stretford & Urmston, Warrington, Northwich, Chester, Crewe & Nantwich, Congleton.
Need steel beam & rsj installation?
Send photos or your engineer's drawings for a same-day budget price, or book a free survey.