RSJ installation · Cardiff
RSJ installation in Cardiff
RSJ installation across Cardiff, designed by a structural engineer and signed off by building control.
- Itemised written quote
- Beam sized by a structural engineer
- Covering Cardiff and nearby
- Free survey visit
- Engineer's calculations arranged
- Building control handled
- Fixed written price once scope is agreed
- England, Wales, mainland Scotland & NI
What RSJ installation involves in Cardiff
RSJ installation is the supply and fitting of a structural steel beam to carry load across an opening or in place of a wall. RSJ stands for rolled steel joist, an older name for an I-shaped steel section; most domestic beams today are universal beams. Installation covers fabrication to the engineer's design, delivery, lifting, bedding on padstones and packing tight.
Across Cardiff, RSJ installation usually comes up when people want more light, a better layout or a way through to a new extension. We cover the city and its surrounding districts. Whatever the reason, the beam is sized from calculations and the work is inspected before anything is covered.
Key points for your project
- Heavy steels are raised with suitable lifting equipment rather than by hand alone. Manual handling is planned so nobody carries more than is safe, and the lift is coordinated so the beam goes up level onto both bearings together.
- Padstones spread the concentrated load from each beam end into the masonry below. They may be concrete, engineering brick or a steel plate, depending on the engineer's design and the strength of the wall beneath.
- Steel for internal use is normally delivered with a primer coat to protect it during installation. Beams in damp positions, within external walls or exposed outside need a more robust coating or galvanising, as the engineer specifies.
- An RSJ inside a home commonly needs 30-minute fire resistance where it supports elements of structure. Fire-rated plasterboard boxing is the usual method, with intumescent paint used when the beam is to remain visible.
- If you already hold calculations from an architect or engineer, we install to those. Where something on site differs from the drawing, such as a weaker wall or a different joist direction, the engineer is asked to confirm before work carries on.
How the job runs in Cardiff
Look and measure
We check the wall, the span you want and what the wall is carrying, and photograph anything the engineer needs to see.
Design and price
Calculations come back from the engineer and we confirm your fixed written price, line by line.
Building control
We submit the application or notice to Cardiff Council under the Building Regulations as they apply in Wales, before work starts.
Fit, inspect, finish
The work is propped and the steel installed and packed tight. After inspection the opening is boxed, plastered and left clean.
What does RSJ installation cost in Cardiff?
As a guide, budget £730–£2,280 per beam including VAT for rSJ supply and fit (single beam) in Cardiff, based on published UK cost guides adjusted for prices in Wales (-9%).
| Job | Typical guide range | What it usually covers |
|---|---|---|
| RSJ supply and fit (single beam) | £730–£2,280 per beam | Beam supplied, delivered, lifted and packed on padstones, with propping (calculations and approval priced separately) |
| Temporary works and propping | £140–£460 | Props, spreaders, needles and sole plates for a typical opening, installed and struck |
| Steel beam replacement | £1,800–£5,000 | Propping, removing the failed beam, new steel on proper bearings, approval and making good |
| Fire protection to a steel beam | £140–£550 per beam | Fire-rated board boxing or an intumescent coating system as specified |
Figures include our approximate regional adjustment for prices in Wales (-9%) and are rounded. How these figures are worked out.
Building rules for Cardiff
Welsh building regulations treat beams and new openings as controlled building work. We apply to Cardiff Council on your behalf before anything is removed, give the commencement notice the 2026 Welsh rules require, and the steel is checked before it is boxed in.
Where the steel bears into a wall shared with next door, notice must be served under the Party Wall etc. Act 1996. If your neighbour dissents, surveyors agree how the work is done before it starts.
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Questions about RSJ installation in Cardiff
Do you cover Cardiff for RSJ installation?
Yes. We carry out RSJ installation in Cardiff. Book a free survey visit and we will check the wall, arrange the engineer's calculations and send an itemised written quote.
What happens at the survey visit in Cardiff?
We look at the wall, the floor and ceiling either side and what sits above, measure the opening you want, and note cables, pipes and access for the steel. It usually takes under an hour and there is no charge.
How is an RSJ installed?
The structure above is propped, the wall or opening is prepared, and padstones are bedded at each end. The beam is lifted onto them, bolted where needed and packed with shims and dry-pack. Props come out once it is carrying, building control inspects it, and the steel is then fire protected and finished.
How heavy is an RSJ and how is it lifted?
Weight varies widely with the section and length, from beams a small team can carry to steels needing mechanical lifting. The lift is planned at the survey, using enough people, trolleys and suitable lifting equipment so the beam goes up safely and level onto both bearings.
What does RSJ stand for?
RSJ stands for rolled steel joist. It was the name for a hot-rolled I-shaped steel section with tapered flanges, and it is still used loosely for any steel beam in a house. Most steels fitted in homes today are universal beams, which do the same job with parallel flanges.
Who decides what size RSJ I need?
A structural engineer. The size depends on the span, the loads from floors, walls and roof above, how stiff the beam needs to be and how its ends are supported. We arrange calculations from a qualified engineer, or fit to calculations you already have, rather than guessing a size.
Do I need a party wall agreement for RSJ installation in Cardiff?
Yes, if the beam bears into a shared wall: the Party Wall etc. Act 1996 applies in England and Wales, and a party structure notice must be served at least two months before that work starts. We arrange it through a party wall surveyor.