Building Control and structural work: what you need to know

Does structural work need Building Control approval?

Yes, in nearly every case. Removing a load-bearing wall, taking out a chimney breast, converting a loft, building an extension, underpinning, adding a storey or cutting a large new opening are all building work under the Building Regulations. Part A of the regulations deals with structure, and Building Control must be satisfied that the work complies before it is signed off.

Approval is about safety and compliance, not appearance. Building Control checks that the structure will stand up, that fire safety, insulation, drainage and ventilation meet the regulations, and that the work on site matches what was approved. Minor like-for-like repairs usually fall outside the regulations, but if you are unsure, ask Building Control before you start.

Responsibility sits with the owner as well as the builder. If work is done without approval, the council can take enforcement action, and the problem tends to surface years later when you come to sell. Applying at the start is almost always quicker and cheaper than putting things right afterwards.

Planning and Building Regulations are separate

Many people assume that planning permission covers everything. It does not. Planning deals with how a building looks, how it affects neighbours and how land is used. Building Regulations deal with how it is built.

A project can need both, one or neither. A rear extension under permitted development may need no planning application but will still need Building Regulations approval. An internal wall removal rarely needs planning but nearly always needs Building Control if the wall is load-bearing.

Other consents can sit alongside both. Listed buildings need listed building consent even for internal structural changes. Flats usually need the freeholder's written consent under the lease. Work on or near a shared wall may trigger the Party Wall etc. Act 1996. None of these replaces Building Regulations approval, and Building Regulations approval does not replace any of them.

The three routes to approval

There are three ways to get structural work approved, and the right one depends on how far the project has progressed and how much certainty you want before the builder starts.

• Full plans: you submit drawings and structural calculations before work starts, and Building Control checks them and issues a decision, normally within five weeks or two months if you agree an extension. This gives the most certainty and is the usual route for extensions, lofts and anything substantial.
• Building notice: you give notice and can start work shortly afterwards without plans being formally approved. The inspector still asks for calculations as the work goes on. It suits small, simple jobs, but any problem is found on site rather than on paper.
• Regularisation: for work already carried out without approval, the council's Building Control can assess it retrospectively. This often means opening up finished work so the inspector can see beams, bearings or foundations.

Council or private approver?

You can use your local council's Building Control team or a registered private approver. Both apply the same regulations and both issue a completion certificate at the end. Councils and private approvers set their own charges, so it is worth comparing.

There are differences in practice. Only the council can deal with regularisation of work already done. Private approvers are appointed by you and notify the council that they are acting. Switching from one to the other partway through a job is possible but adds paperwork, so it is best to choose at the start and stick with it.

For structural work, the choice matters less than the timing. Whichever body you use, appoint them before the builder starts, give them the engineer's package early, and make sure the builder knows who to call for each inspection. A common cause of delay is an inspector learning about a beam after it has already been plastered over.

What Building Control needs from your engineer

For a structural job, the heart of the application is the engineer's calculations and drawings. They show the loads, the member sizes, the bearings and the foundations, along with any connection details and the sequence for temporary support. The inspector or a checking engineer reviews them and may raise questions before approving.

We send inspection reports, calculations and drawings to Building Control and liaise with them directly, which keeps technical queries out of your inbox. Before anything is issued, each package is checked in three stages, ending with approval by our Head of Engineering, so queries tend to be about clarification rather than errors. Our guide on what structural calculations contain explains the package in more detail.

Inspections during the build

Approval on paper is only half the process. The builder must notify Building Control at key stages so the inspector can see work before it is covered up. The exact list depends on the project, but for structural work it usually includes the stages below.

Missing an inspection is a common and avoidable problem. If a steel beam is boxed in before it is seen, the inspector may ask for the boxing to be opened up again. A structural steelwork inspection report from the engineer can also help where the inspector wants independent confirmation.

• Commencement of work
• Foundation excavations, before any concrete is poured
• Oversite and damp-proof course
• Drainage, before trenches are backfilled
• Steel beams, padstones and connections, before they are fire protected and plastered
• Completion, once all work is finished

The completion certificate and selling later

When the inspector is satisfied, they issue a completion certificate. It is the proof that the work was approved, and buyers' solicitors ask for it on almost every London sale where structural work has been done. Store it with your deeds.

If a certificate is missing, the usual options are regularisation through the council or, for some buyers, an indemnity insurance policy. Insurance covers the legal risk but says nothing about whether the structure is safe. Our guide to retrospective Building Regulations approval explains how an engineer helps when old work has no paperwork.