An RSJ is the steel beam that carries the load once a wall is taken out. We survey, appoint a structural engineer, prop the structure, install the beam and padstones, make good and book the inspections. We build to the calculations the engineer issues, and we never produce those calculations ourselves. This page sets out what an RSJ job on a Letchworth Garden City property involves, and who has to approve it.
A steel beam inside the house is not on the Heritage Foundation's consent list
The Heritage Foundation's published list of works needing consent is external only, and internal structural work does not appear on it. The Foundation states that if you wish to make external changes to your home you need to apply for its consent. Removing an internal load bearing wall and fitting a steel beam is not one of the works it lists.
That does not remove the Foundation from the picture. It states that its consent requirement is separate from the permission required from the local authority under planning and listed building legislation and the building regulations. So where your scheme also changes the outside, a widened rear opening or a new window, the Foundation application runs alongside the building control notice rather than instead of it. We flag which parts of the job fall each side of that line at survey.
The building control notice for your beam goes to Hertfordshire Building Control
Building control for Letchworth is carried out by Hertfordshire Building Control Limited. North Herts Council owns that company along with seven other Hertfordshire local authorities, so the notice for your beam does not go to a council building control counter.
We make that application and book the inspections around the steel going in. The propping, the bearings and the beam itself each need to be seen at the right stage rather than after the plaster is on. Sequencing those against the engineer's calculations is our job, not yours.
What the beam bears on depends on how the wall was built
A steel beam concentrates the load above it onto two small bearing points, so the make up of the wall at each end decides the detail. The Letchworth Conservation Area Appraisal records that in a number of Letchworth houses brick is used to almost mid height of the building with roughcast above. It also records that brick is largely used for the plinths of roughcast buildings.
For Area One, the Cheap Cottages Exhibition streets, the appraisal lists walling materials as red brick, roughcast, and rendered cement panels or blocks painted off white or cream. Timber framing, hanging tiles and weatherboarding are used to accentuate gables. A bearing detail drawn for solid brick does not transfer to a rendered block wall. We open up and record what is actually there before the steel is ordered.
On the Jackmans Estate the steel arrives from the parking court side
The Jackmans Estate was laid out on the Radburn principle, so houses front pedestrian routes and green space and back onto parking and garage courts. It is a post war estate in the south of Letchworth. Valuation Office Agency figures for 31 March 2025 show 1,350 of the 2,800 dwellings in the Letchworth South East area were built between 1965 and 1972.
A steel beam arrives on a lorry and is carried in by hand. Where the front door faces a footpath, the delivery point, the carry route and the skip position all have to be agreed from the court side first. We settle that before the order goes in, so the steel is not sitting on a verge while access is argued about.
- Steel columns, base plates and bolted connections
- Access and lifting plans for restricted London sites
- Ceiling and floor levels resolved where the beam sits below joists
- Flitch beams where a slimmer steel and timber solution suits
- Structural engineer's calculations arranged and followed
Why Letchworth Garden City Homeowners Choose GS Renovation
We are a contractor, not an engineering practice. For a Letchworth beam we appoint the structural engineer, build to the calculations issued, and hold the propping until the steel is in and bearing correctly. We make the building control application to Hertfordshire Building Control and book the inspections around our own programme, so one person answers for the engineer, the steel and the sign off. GS Renovation Ltd is fully insured and registered in England, company number 14611254. Quotations are free and carry no obligation.
- Steel ordered cut, drilled and primed to the schedule
- Structural engineer instructed and coordinated on your behalf
- Straight advice on what is and is not worth spending money on
- Rated 4.9 from 31 reviews on MyBuilder
- Neighbours given notice before the noisy stages
- Steel sized to the engineer's design, never guessed on site