RSJ installation · Carmarthenshire
RSJ installation in Carmarthenshire
RSJ installation across Carmarthenshire, designed by a structural engineer and signed off by building control.
- Itemised written quote
- Beam sized by a structural engineer
- Covering Carmarthenshire and nearby
- Free survey visit
- Engineer's calculations arranged
- Building control handled
- Fixed written price once scope is agreed
- England, Wales, mainland Scotland & NI
Planning RSJ installation in Carmarthenshire
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.
We carry out RSJ installation throughout Carmarthenshire, for homeowners, landlords and builders who need the structural part done properly. We can survey in places such as Llandeilo, Ammanford and Burry Port and the villages around them. You get an itemised written quote that shows the calculations, approvals, steel, labour and finishing as separate lines.
What to expect
- The engineer chooses the section type for the job. Universal beams suit most spans, universal columns are stockier and used as posts or where depth is limited, parallel flange channels fit against walls or timbers, and box sections suit slim or exposed members.
- RSJ originally meant a rolled steel joist with tapered flanges. Most beams supplied for homes today are universal beams with parallel flanges, but the term RSJ has stuck, and builders, engineers and building control all understand what it means.
- Where a long beam cannot be carried into a property in one piece, the engineer can design a bolted splice so it arrives in two or more lengths. The splice position and bolts are part of the calculations and must be installed exactly as drawn.
- Floor joists can rest on the bottom flange, hang from timber packers bolted into the web, or be notched to sit over the steel. The engineer specifies the connection, and it affects how flush the finished ceiling can be.
- Packing is what makes the beam work. Steel shims and dry-pack mortar fill the gap between the top flange and the structure above, so the load transfers onto the steel without the floor or wall settling down onto it.
How the job runs in Carmarthenshire
Free visit
A short visit to Carmarthenshire to see the job, agree what you want and check the bearings, floors and services that affect the design.
Calculations
The engineer's calculations and a simple drawing are prepared for your opening and shared with you before anything is ordered.
Building control
We submit the application or notice to Carmarthenshire County Council under the Building Regulations as they apply in Wales, before work starts.
Steel in, made good
On site we prop, open up, fit and pack the steel, then fire protect, box in and plaster once the inspection is done.
Guide prices for RSJ installation in Carmarthenshire
As a guide, budget £730–£2,280 per beam including VAT for rSJ supply and fit (single beam) in Carmarthenshire, 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 |
| Structural calculations for a beam | £230–£680 | Site measure or photos, beam and padstone design and calculations for building control |
| 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 Carmarthenshire
In Wales, structural alterations come under the Building Regulations 2010 as they apply in Wales. Carmarthenshire County Council handles building control for Carmarthenshire. For work started or approved from 1 July 2026, the Welsh system uses an application to building control, dutyholders appointed in writing, a commencement notice before work starts and a compliance statement at the end.
The Party Wall etc. Act 1996 applies in Wales as well as England, so a beam bearing into a shared wall needs a party structure notice at least two months before work starts. We arrange notices through a party wall surveyor.
RSJ installation by town
Questions about RSJ installation in Carmarthenshire
What happens at the survey visit in Carmarthenshire?
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.
Who approves RSJ installation in Carmarthenshire?
Structural work in Carmarthenshire needs a building control application to Carmarthenshire County Council under the Welsh regulations, with a commencement notice before work starts. We prepare and submit it with the structural engineer's calculations and arrange the inspections, so the completion paperwork follows the job.
Is an RSJ the same as a steel beam?
In everyday use, yes. Builders and homeowners call most steel beams RSJs, whether they are universal beams, channels or columns. Technically an RSJ is one particular older section shape, but the engineer's drawing names the exact section type, so there is no confusion on site.
What is included in an RSJ supply and fit price?
Our itemised written quote sets out the calculations, building control, steel and fabrication, delivery, lifting, padstones, propping, labour, fire protection and making good as separate lines. Once the specification and scope are agreed, the price is fixed in writing, so you know the full cost before work starts.
Can an RSJ be delivered in sections?
Yes, where access is tight. The engineer can design bolted splice joints so a long beam arrives in two or more pieces and is joined in place. The splice has to be part of the calculations from the start, because it changes how the beam carries load at that point.
Can you fit an RSJ to my own engineer's calculations?
Yes. We install to calculations and drawings from your engineer or architect, as long as they cover the beam, bearings and any columns or connections. If site conditions differ from what the design assumed, we check with the engineer before carrying on.
Which towns in Carmarthenshire do you cover?
We cover towns including Llanelli, Ammanford, Carmarthen and Burry Port, plus the villages and smaller towns around them.