Structural Calculations in London
Any building work that alters how loads travel through a property needs structural calculations for building control. Wimbledon Surveyors provides clear, buildable calculations across London for extensions, loft conversions, beam installations and more. Request calculations.
What Calculations Are For
Structural calculations prove to building control that new beams, foundations and connections are correctly sized to carry the loads safely — a requirement before work can be signed off.
Beams, Foundations & Connections
We size steel and timber beams, design foundations for extensions, and detail the connections that hold everything together, providing drawings your builder can work from.
Fast Turnaround for Builders
We understand projects move quickly, so we produce calculations promptly to keep your build and your building-control sign-off on schedule.
Paired With Design
Calculations usually accompany our extension and loft design and load-bearing wall removal service for a complete package.
Get Your Calculations
Send us your plans and we will quote for the calculations your project needs. Contact us to get started.
Structural Calculations for Building Control Approval
Every structural alteration to your home — a knock-through, a new opening, a loft conversion, an extension — needs calculations proving the structure will safely carry its loads. Building Control will not sign off steelwork, and most builders will not order a beam, without them. We produce clear, accurate structural calculations for projects across London and Essex, delivered quickly, priced fixed, and supported until your Building Control body confirms approval.
Calculations We Provide
- Steel beam calculations — sizing beams for load-bearing wall removals, garage conversions and new openings, with padstone and bearing checks.
- Loft conversion packages — floor beams, ridge and purlin design, dormer structure and staircase trimming.
- Extension design — foundations, lintels, roof structure and steel frames for single and double-storey extensions.
- Timber design — joist sizing, flitch beams, trimming around openings and flat roof structure.
- Foundation checks — bearing pressure and depth verification, including near trees on London clay.
- Structural surveys of existing members — verifying whether existing beams and walls can take proposed loads.
What Building Control Expects
Calculations must demonstrate compliance with the structural Eurocodes and Approved Document A, cover every affected load path, and be legible to the checking engineer. Packages that arrive incomplete — a beam sized with no bearing check, or a dormer with no wind-load consideration — bounce back and stall projects for weeks. Ours are prepared to be approved first time, and if the checker raises queries we answer them at no extra cost until approval.
How the Process Works
Send us your architect’s drawings — or arrange a visit where no drawings exist — and we confirm a fixed fee and timescale. We then prepare the calculations and any necessary sketches, issue them for your Building Control application, and remain on hand for builder queries about steel sizes, connection details and temporary works during construction. Most single-beam calculations are delivered within a week; full loft or extension packages within two.
One Team from Design to Sign-Off
Because we are surveyors and engineers in one practice, we can also handle the matters that surround the calculations: party wall notices where the steel bears on a shared wall, defect reports where the existing structure needs assessment first, and monitoring where movement must be tracked. It is one instruction, one point of contact, and no gaps between professionals.
Frequently Asked Questions
Single steel beam calculations typically cost between £200 and £400 in London; loft conversion and extension packages more, depending on complexity. We confirm a fixed fee up front — and answering Building Control queries is included.
Simple beam designs are usually delivered within three to five working days; complete loft or extension packages within one to two weeks. Urgent turnaround is often possible — tell us your builder’s start date.
If the wall is load-bearing, yes — Building Control requires calculations for the supporting beam and its bearings before approving the work. Even where a wall appears non-loadbearing, it should be verified by an engineer before removal.
Where your architect’s drawings contain sufficient information, often yes — which saves cost. If load paths or existing construction are unclear, a short inspection ensures the design is based on what is actually built rather than assumptions.
Yes — alongside the calculation pack we state beam sizes, steel grades, padstones and bearing requirements in plain terms, and we are available to answer your builder’s questions during installation.