Building Regulations Structural Calculations: 7 Things You Must Submit for Approval

Building regulations structural calculations are required for almost every residential project that involves a change to the structure of your home. Whether you are removing a load-bearing wall, adding a loft conversion, building a rear extension or replacing a chimney breast, Building Control will ask for building regulations structural calculations before approving the work. Without them, the project cannot proceed lawfully and your contractor cannot close up the structure for inspection.

Building Regulations Structural Calculations: When Are They Required?

Building regulations structural calculations are needed whenever you alter, extend or construct any structural element. This includes removing or altering load-bearing walls, installing steel beams (RSJs), building single or multi-storey extensions, converting lofts into habitable rooms, removing chimney breasts (partial or full), underpinning foundations, constructing retaining walls over 1m high near highways, and installing new openings in external walls for bifold or sliding doors.

Even if your project is covered by Permitted Development and does not need planning permission, building regulations structural calculations are still required. Planning permission and Building Regulations approval are two entirely separate processes. One deals with what you are allowed to build; the other deals with how it is built safely.

Building Regulations Structural Calculations: Approved Document A (Structure)

Approved Document A is the primary document that governs building regulations structural calculations. It covers the structural design of buildings and sets out the requirements for loading, ground movement and disproportionate collapse. Part A is split into three sections.

Building Regulations Structural Calculations: The 7 Things You Must Submit

Building Regulations Structural Calculations: Full Plans vs Building Notice

There are two routes to Building Regulations approval. The Full Plans route involves submitting building regulations structural calculations and drawings to Building Control before work starts. The plans are checked, and you receive a formal approval notice. This is the recommended route for any project involving structural work because it gives you certainty before construction begins.

The Building Notice route does not require plans to be submitted in advance. You simply notify Building Control that work is starting. However, the inspector will still require building regulations structural calculations to be available on site, and if the structural design is inadequate, you may be required to open up completed work for inspection or even demolish and rebuild. For structural work, the Full Plans route is almost always safer and cheaper in the long run.

Building Regulations Structural Calculations: How the Approval Process Works

Once building regulations structural calculations are submitted via the Full Plans route, Building Control has 5 weeks (or 2 months if you agree an extension) to review them and either approve, reject or request amendments. In practice, most residential submissions receive a response within 2 to 3 weeks.

If amendments are required, the structural engineer revises the calculations and resubmits. Once approved, work can begin. The Building Control inspector will visit site at key stages: excavation of foundations, placement of reinforcement, pouring of concrete, installation of steelwork, and final completion. At each stage, the inspector checks that the work matches the approved building regulations structural calculations.

Building Regulations Structural Calculations: Do I Need a Structural Engineer?

Building Control does not legally require that building regulations structural calculations are prepared by a chartered structural engineer. However, in practice, Building Control bodies will not accept calculations unless they are prepared or checked by a suitably qualified person. Most Building Control inspectors will ask for the engineer's qualifications and professional registration (CEng, MIStructE or equivalent) as a condition of acceptance.

Using a qualified structural engineer also protects you legally. If something goes wrong with the structure, professional indemnity insurance provides a route to compensation. An unqualified person producing building regulations structural calculations has no such cover.

Building Regulations Structural Calculations: Frequently Asked Questions

How much do building regulations structural calculations cost?

At SECalcs, building regulations structural calculations start from £245 for a single beam design (e.g. wall removal). Loft conversions typically cost £395 to £595. Full extension packages with multiple beams, columns and foundations start from £595. Call 07359 267907 for a quote.

How long does it take to get Building Regulations approval?

Building Control has 5 weeks to respond to a Full Plans application. In practice, most residential submissions are reviewed within 2 to 3 weeks. The structural calculations themselves typically take 3 to 5 working days to prepare.

Can I start work before Building Regulations approval?

You can start work under a Building Notice without waiting for formal approval, but Building Control must be notified. For structural work, this is risky because if the design is rejected, you may need to undo completed work. The Full Plans route is strongly recommended.

What happens if I do structural work without building regulations structural calculations?

The local authority can issue an enforcement notice requiring you to either demonstrate compliance retrospectively or remove the non-compliant work. This also causes problems when you sell the property, as solicitors will flag the absence of Building Regulations completion certificates.

→ Need building regulations drawings? See our Building Regulations Drawings page. Wall Removal Structural Calculations → Loft Conversion Structural Calculations → Ground Floor Extension Steel Beam → How to Read Structural Drawings →