An RSJ is the steel beam that carries the load once a wall, or part of one, is taken out. GS Renovation installs beams in Potters Bar as a contractor. We appoint a structural engineer, build to the calculations they issue, and never produce those calculations ourselves. Indicative London ranges, MyBuilder and Checkatrade, 2026, put a beam alone in one straightforward opening at £1,500 to £4,000. Quotations are free and carry no obligation.
Who produces the calculations for your beam
A Chartered Structural Engineer does, and we appoint one for you. Hertfordshire Building Control states that structural calculations should be designed or checked by a Chartered Structural Engineer, MIStructE, and that an additional fee of £75 plus VAT may apply if its consultant engineers have to review them. That fee is worth knowing about before anything is submitted.
Hertfordshire Building Control lists structural details and structural calculations among the items that may be required to justify the stability of a proposal, giving loft conversions and larger projects involving steelwork as its examples. A beam sized on the back of a quotation is not that. The paperwork comes first, then the steel is ordered.
What building control checks on a beam installation
Hertfordshire Building Control examines structural beams and openings, among matters including foundations, ground and floors, damp proofing, roof structure, drainage, fireproofing and thermal insulation. In Hertsmere that is the service Hertsmere Borough Council links to from its own planning and building control pages. We make the booking and meet the surveyor on site.
For steelwork the parts that matter are the bearings, the padstones and the fire protection. Those need to be seen before anything is boarded over, so we set the programme around the inspection rather than the other way round.
Steel over a garage when you build above it
It carries the new first floor, and the planning position decides where it can sit. Hertsmere's design guide deals with a first floor extension proposed over an existing ground floor side extension built closer than 2 metres to the boundary. In that case a minimum 2 metre set-in is likely to be required at first floor level. The set-in changes the span and the load path, so the engineer works from the approved drawings, not the sketch.
- Existing pipework and cabling diverted around the new opening
- Structural openings for open-plan living
- Making good, plastering and finishing around the new steel
- Goalpost frames where two walls meet at a corner
- Level, plumb and deflection checks before props are struck
Trusted RSJ and Steel Beam Installation in Potters Bar
We are a contractor, not a structural engineer, and we keep the difference clear. The engineer we appoint sizes the beam and issues the calculations, and we build to them. We also coordinate the building control application and the inspections, so there is one point of contact from the first survey through to the completion certificate. GS Renovation Ltd is fully insured and registered in England, company number 14611254. Our founder, Abdelaaziz Saaid, has over 30 years of hands on experience.
- Building control applications and inspections coordinated for you
- Clean, tidy and reliable tradespeople
- Building control inspected at the propping and beam stages
- Beams boxed and fire protected to the approved detail
- A dedicated project manager from first survey to handover
- Paperwork and certificates handed over for when you sell