Building regulations
What building control actually inspects
The stages an inspector attends, why foundations are the one you cannot miss, and what the completion certificate is worth when you sell.
Two systems, not one
Building control is separate from planning. Planning decides whether you may build; building control decides whether what you built is safe, warm, and properly drained. A permitted development extension needs no planning application but absolutely needs building control.
You can use the local authority's building control team or an Approved Inspector. Either way, an application is made before work starts and the work is inspected at set stages.
The inspection stages
Commencement, before work starts. Excavation, once foundation trenches are dug and before concrete is poured. Foundations, once poured. Damp proof course, oversite and drainage before covering. Structural elements — steel beams and their padstones — before they are cased in. Insulation before it is boarded over. Drains, tested. Then completion.
Foundations and drainage are the stages people most often miss, because they happen fast and they get covered. An inspector who arrives after the concrete is poured can require it to be opened up.
The parts that apply most often
Part A covers structure — beam sizing, bearings, foundation depth. Part B is fire safety, which drives loft conversion design. Part C is site preparation and moisture. Part H is drainage. Part K covers stairs, ramps and guarding. Part L is conservation of fuel and power — insulation levels, airtightness, and glazing performance. Part P covers electrical safety in dwellings.
Why the certificate matters later
At the end, building control issues a completion certificate. This is the document a buyer's solicitor asks for when you sell the house — and the absence of one is a standard reason for a sale to stall or for a retention to be demanded.
Electrical work generates its own paperwork under Part P, and replacement glazing generates a FENSA or equivalent certificate. Keep all of it together; that pack is worth real money at resale.
This guide describes national rules for England and was written to be accurate at the time of publication. Local designations can restrict them further, and legislation changes. Always confirm the position for your own address with your local planning authority, or ask us to do it in writing.
Answers
Questions we get asked alongside this
Do I need planning permission for building work in London?
It depends on the property type and what is proposed. Many single-storey rear extensions and loft conversions fall under permitted development, but those rights do not apply to flats and are restricted in conservation areas or where an Article 4 direction applies. We check the planning position for your specific address before quoting, and tell you in writing which route applies.
How do you price the work?
From a site survey, written up as a fixed and itemised scope before any deposit is discussed. If something genuinely unforeseen appears once work is opened up, it is priced and agreed in writing before we continue — never added to the final invoice after the fact.
When do I pay?
In arrears of work completed. You pay for work that has been done and inspected, not for work that has been promised. This has been how the company operates since 2008.
Do you handle Party Wall notices?
Yes, where the work requires them. Under the Party Wall etc. Act 1996, notifiable work on a shared wall needs 2 months written notice to the adjoining owner, while excavation near a neighbouring structure and building at the line of junction need 1 month. We serve the notices and manage the award process as part of the job.
Will I get certificates at the end?
Yes. Electrical work is tested and certificated under Part P, and building control issues a completion certificate where an application was required. You receive the handover pack — it is what a buyer's solicitor will ask for when you eventually sell.
How long will it take?
It depends entirely on scope, and we give a programme with the written quote rather than a guess on the phone. What we will not do is start a job we cannot resource, which is the usual reason a build stalls halfway through.
More guides
Related reading
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