Building regs guide · England & Wales

Structural calculations.

Whenever you change the structure of your home — removing a wall, fitting a steel beam, forming a big opening — building control needs structural calculations from a structural engineer to prove it is safe. Here is when you need them and how we provide them as part of your project.

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What are structural calculations — and when do you need them?

Structural calculations are the engineer’s figures showing that beams, foundations and altered walls will safely carry the loads above them. Building control requires them alongside your building regulations drawings for any structural work.

You will need them whenever you remove or alter a load-bearing wall, install a steel beam (RSJ), form a large opening for bifold doors, build an extension, convert a loft, or remove a chimney breast. Without them, building control cannot sign the work off.

On our Standard and Premium packages, an accredited structural engineer’s calculations are included and coordinated with your drawings, so everything reaching building control is consistent. See our packages.

What we calculate, and when you need it

A structural engineer sizes the parts of your project that carry load. Here is what that covers, and the projects that need it.

What the engineer calculates

  • Steel beams (RSJs), lintels and padstones
  • Foundations for extensions and new walls
  • Floor and roof joists, including loft floors
  • Load-bearing wall removal and new openings
  • Retaining walls and ground conditions where relevant

When you need them

  • Knocking two rooms into one or going open-plan
  • Loft conversions — new floor and dormers
  • Rear, side and two-storey extensions
  • Removing a chimney breast
  • Large openings for bifold or sliding doors
Structural calculations are not the same as building regulations drawings — the calculations size the structure, the drawings show how it is built. Building control wants both, which is why we keep them under one roof and one fixed price.

How Arkiplan handles your structural calculations

We are an online architectural design service — the practical alternative to a traditional high-street architect. We bring in an accredited structural engineer, size the structure from an accurate survey, and hand building control a package that matches your drawings exactly.

Structural calculations FAQ

When do I need structural calculations?

Whenever you alter your home’s structure — removing or altering a load-bearing wall, fitting a beam, forming a large opening, building an extension, converting a loft, or removing a chimney breast. Building control requires them to sign the work off.

Are structural calculations the same as building regulations drawings?

No. The calculations size the structure (beams, foundations, joists); the drawings show how it is all built. Building control needs both, and they must agree with each other.

Who produces structural calculations?

A qualified structural engineer. On the relevant Arkiplan packages we bring in an accredited engineer and coordinate their calculations with your drawings.

Are structural calculations included in your packages?

Yes — an engineer’s calculations are included on our Standard and Premium packages. The Essentials package covers planning drawings only. Compare them on our pricing page.

Does building control check the calculations?

Yes. Building control reviews the structural calculations as part of approving the work, and inspects the structure on site as it is built.

Will the engineer need to visit my home?

Often not — the calculations are usually based on the accurate measured survey and drawings. Where a project is more complex, a site visit can be arranged.

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This guide is general information, not formal advice; building regulations and building control procedures change and depend on your specific project, property and local authority. We confirm the current position for your project as part of every job.