Guide
Structural calculations for building control: what a beam needs
Updated
Fitting a beam is notifiable building work. Here is what steel beam calculations for building control must show, the two ways to notify, and the certificate's value.
Question 1
What is the clear span of the opening, in metres?
Measure the structural opening. The beam itself will be longer, because it has to bear on masonry at each end; how much bearing, and on what padstone, comes out of the calcs rather than a rule of thumb. Between sizes? Round up.
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What building control actually checks
- Calculations from a competent person, in practice a structural engineer, showing the loads carried, the section's adequacy in strength and deflection, bearing and padstone design, and lateral restraint (gov.uk: building regulations approval).
- The work on site matching the calcs: the specified section, the specified padstones, proper bearing length, fire protection to the steel where required.
- Structural adequacy under Part A of the Building Regulations (Approved Document A). What will not satisfy that on its own: a span table printout, a steel supplier's suggestion, or an online checker's output, including ours.
Full plans or building notice
Two routes to the same duty:
- Full plans
- Calcs and drawings are checked before work starts. Slower to begin, but disputes surface on paper instead of on site.
- Building notice
- No advance check: the inspector judges the work as it happens, and anything wrong gets rebuilt.
Either way, regulation 16 of the Building Regulations 2010 says work must not start until two days have elapsed since the end of the day you gave notice. For a single beam either works. Builders who know their building control team often use a notice; cautious owners prefer full plans. Both involve inspections and, at the end, a completion certificate.
Each council or private building control approver sets its own fees; there is no national scale. Published 2026 domestic scales we read run from about £200 to £400 for this kind of job.
Bury charges £206 including VAT for structural alterations costing up to £2,000. Coventry charges £400 for minor work, including removing a load-bearing wall or forming a new structural opening valued under £7,500.
Some councils price off the value of the works and come out higher, and regularisation costs more again. Check your own council's published scheme.
The completion certificate is the asset
Years later, nobody asks how big the beam was. They ask for the certificate: the buyer's conveyancer, the remortgage lender, occasionally the insurer after a claim.
Work without sign-off means a retrospective regularisation application at a higher fee. The council can require opening up of finished work to see the steel and padstones, and you pay an engineer to assess what should have been calculated first.
Indemnity policies sold at sale cover legal risk, not the structure. The certificate costs a fee and a few inspections now; its absence costs a renegotiation later.
Not sure what your opening needs? Run the checker for the indicative range, then get the calcs, that is the document building control actually wants.