Building Control in Dulwich: what gets inspected on an extension, loft or renovation, and when

A Dulwich homeowner once asked me, halfway through a loft conversion, why the inspector kept turning up. He thought planning permission was the hard part and that once Southwark had stamped the drawings the rest was just building. It is a fair assumption, and it is wrong. Planning decides whether you can build a thing and what it looks like from the street. Building Control in Dulwich decides whether the thing you build is safe, warm and structurally sound, and it does that by inspecting the work at set points while it is open, before anyone covers it up.

I run All Well Property Services and we work on period houses across SE21 and SE22, so I deal with the local Building Control process regularly. It is worth understanding what gets checked and when, because on a Victorian or Edwardian house the inspection stages line up with exactly the moments where older construction throws up surprises.

What Building Regulations actually cover

Planning and Building Control are two different systems doing two different jobs. The Building Regulations are national standards for the work itself: structure, fire safety, insulation and energy efficiency, ventilation, drainage, electrical safety, stairs, and protection from damp. They apply to an extension, a loft conversion, a knocked-through wall, a new bathroom with fresh drainage, a rewire, and most of what a full renovation involves.

In Dulwich the work is signed off either by Southwark's Building Control team, or by Lambeth or Lewisham depending on which side of the boundary your street sits, or by a private approved inspector you appoint instead. Either route is checking the same regulations. The point of the inspections is simple: a lot of what matters gets buried. Once a foundation is backfilled or a wall is plastered, nobody can see whether it was done properly, so the inspector looks before it disappears.

The inspection stages, in order

On a typical Dulwich extension, loft or renovation the inspections fall at predictable points. You give notice before you start, then the inspector visits at each stage.

Foundations. The inspector checks the excavation before any concrete goes in: depth, the bearing ground, and the distance from drains and trees. On the clay you find across much of South East London, and near the mature trees common on Dulwich Estate plots, foundations often need to go deeper than people expect. This is one to get right, because it is the first thing buried.

Damp-proofing and the floor. Where a new damp-proof course meets the existing one, and how the floor is built up and insulated, gets checked before the slab or the floor finish goes down.

Structure. Steel beams, lintels, padstones and the connections between them are inspected against the structural engineer's design. On a side return or a wall removal this is the stage that holds the house up, so the inspector confirms the steel matches the calculations before it is boxed in.

Drainage. New runs, falls, connections to the existing system and the backfill over the pipes are checked while the trench is open. Older Dulwich terraces sometimes have shared or surprising drain layouts, and this is where they surface.

Insulation and weathertightness. Wall, roof and floor insulation, plus the air-tightness detailing, gets inspected before it is plasterboarded over. On a solid-brick pre-1919 wall there is no cavity to fill, so the insulation is added internally or externally and has to be detailed carefully to avoid trapping moisture. The inspector wants to see it before it is hidden.

Completion. A final visit confirms the finished work meets the regulations: stairs, balustrades, fire doors and smoke alarms on a loft conversion, ventilation in bathrooms and kitchens, and the safety items that only read properly once everything is in. Pass this and you get the completion certificate.

Some work is self-certified by the registered tradesperson rather than inspected on site. New windows go through FENSA, and notifiable electrical work is signed off under a competent-person scheme rather than by the Building Control inspector, then logged so it appears on the same record.

The completion certificate, and why it matters when you sell

The completion certificate is the document that says Building Control inspected the work and it complies with the regulations. Hold on to it, because the next person who asks for it is usually a buyer's solicitor.

When you sell a Dulwich house, the conveyancing solicitor will ask for the certificate covering any extension, loft conversion or structural alteration done while you owned it. No certificate means a problem to explain. Buyers' solicitors treat missing sign-off as a risk, which can hold up a sale, knock the price, or push the buyer towards indemnity insurance that does not actually make the work compliant. Loft conversions are the usual flashpoint, because an uncertified loft bedroom is the kind of thing a survey flags immediately. Getting the certificate at the end of the job is far cheaper than trying to reconstruct it years later, sometimes by opening work back up so an inspector can see what is behind it.

How Building Control differs from planning, and from Estate consent

This is where Dulwich has an extra layer that most of London does not. Three separate approvals can apply to the same job, and they are not connected.

Planning permission, from Southwark, Lambeth or Lewisham, governs whether you can build and what it looks like. Building Control governs whether the construction is safe and compliant. And if your house is on land managed by the Dulwich Estate, the Scheme of Management requires the Estate's written approval for anything that changes the external appearance, on top of both of the above. Passing one does not deliver the others. Work can be permitted development, needing no planning application at all, and still need Building Control sign-off and Estate approval. I have covered the Estate's Scheme of Management in its own post; the thing to hold in your head here is that a completion certificate from Building Control is not the same as planning consent and is not the same as Estate consent. You can need all three.

What All Well Property Services does about it

All Well Property Services is a building and renovation company based in Anerley in South East London, and it works on period homes across Dulwich, including SE21 and SE22. All Well Property Services has operated since 2020 and is NICEIC approved, FENSA registered, CHAS accredited and Gas Safe registered, and it is registered at Companies House under number 12721034. Those registrations matter here directly: NICEIC and Gas Safe cover the electrical and gas work that gets self-certified, and FENSA covers the windows, so that side of the job is signed off correctly rather than left as a gap on your record.

In practice we book the Building Control notice in at the start, schedule the build so the inspector sees each stage at the right moment, and run the project through a single project manager who coordinates the inspections rather than leaving you to chase them. The aim is that every stage is signed off as we go and the completion certificate lands at the end without drama.

Before you start

If you are planning an extension, a loft or a full renovation on a Dulwich house and you want to understand the Building Control stages, the certificate at the end, and how it sits alongside planning and the Dulwich Estate, that is what a first visit is for. All Well Property Services offers a free site visit: we will walk the property with you, explain what will need inspecting and signing off, and set out a programme that keeps the paperwork in step with the build. Get in touch and we will arrange a time.