Building Regulations Renovation UK | London Guide

Many renovation works in London need building regulations approval, even when planning permission does not apply. Building control exists to confirm that work is safe and meets the Building Regulations on structure, fire, electrics, drainage, insulation and ventilation. Structural alterations, electrical work, new drainage, replacement windows, added insulation and wetroom tanking all typically need it. This guide sets out which works are caught, the difference between a building notice and full plans, and why the completion certificate at the end matters as much as the build itself.

What building regulations are, and how they differ from planning

Building regulations and planning permission are routinely confused, but they answer different questions and are enforced by different teams. Planning permission is about whether you may build something, judged on appearance, footprint and use. Building regulations are about how it must be built, judged on safety and performance: will the structure stand, will fire be contained, are the electrics safe, does the drainage work, is the building adequately insulated and ventilated. A project can need one, both or neither. Building control is the function that checks compliance. It is delivered either by the local authority's building control team or by a private approved inspector, and either can sign your work off. Their inspectors visit at key stages, foundations, structural openings, drainage, before covering up, and at completion, and they issue the certificate that proves the work was approved. The key mental shift for renovators is that building regulations apply to specific types of work in their own right, regardless of planning. A loft conversion in an unlisted house outside a conservation area may need no planning permission at all and still require full building control involvement at every stage.

Which renovation works need building control

Building regulations bite on the works that affect safety and performance, and in a typical London renovation that is a longer list than most owners expect. Structural work is the clearest case: removing or altering a load-bearing wall, forming new openings, underpinning, and anything affecting beams, lintels or foundations. New or altered drainage above and below ground is notifiable. Replacing windows and external doors is controlled work, which is why reputable window firms register the installation under a competent person scheme. Electrical work in dwellings is covered by Part P; new circuits and work in special locations such as bathrooms must be either done by a registered competent person who self-certifies or notified to and inspected by building control. Adding or upgrading insulation, controlled fittings such as new bathrooms involving drainage, and the formation and waterproofing of wetrooms all engage the regulations, as does any work that affects fire safety, escape and ventilation. The table summarises the common works and whether building control is typically required.

Renovation work	Building regulations needed?
Remove or alter load-bearing wall	Yes
New opening / steel beam	Yes
New circuits or work in a bathroom (Part P)	Yes
Like-for-like socket / light swap	No
Replace windows / external doors	Yes (often self-certified)
New or altered drainage	Yes
New bathroom involving new waste / drainage	Yes
Wetroom tanking and floor formation	Yes
Adding insulation to walls / loft	Yes
Replastering, redecoration, new kitchen units	No
Loft conversion / extension	Yes

Electrical work and Part P

Part P of the Building Regulations covers electrical safety in dwellings, and it is the area renovators most often get wrong because so much electrical work feels routine. Not all electrical work is notifiable. Like-for-like replacement of a socket, switch or light fitting, and adding a fused spur to an existing circuit, are generally non-notifiable minor works. But installing a new circuit, replacing a consumer unit, and any electrical work in a special location, principally bathrooms and shower rooms, are notifiable and must be certified. There are two compliant routes. The simplest is to use an electrician registered with a competent person scheme such as NICEIC or NAPIT, who self-certifies the work and arranges the building regulations compliance certificate without a separate building control application. The alternative, for an unregistered electrician, is to notify building control in advance so they can inspect and test, which is slower and adds fees. The paperwork that comes out, an Electrical Installation Certificate and a building regulations compliance certificate, is not bureaucratic clutter. It is what an insurer, a buyer's solicitor and a future landlord's EICR all rely on, so insist on it for every job that needs it.

Wetrooms, bathrooms and waterproofing

Bathrooms and wetrooms sit at the intersection of several regulations, and because we repair the failures of badly built ones every week, this is where we urge owners to be most exacting. A new bathroom that involves new waste or drainage engages the drainage and ventilation parts of the regulations: adequate falls, proper traps, mechanical extract ventilation to control moisture, and electrical work to Part P standards. A wetroom goes further, because the floor itself becomes part of the waterproofing: it must be formed to falls toward the drain and tanked so that water cannot reach the structure below. Tanking, the waterproof membrane behind the tiles and across the floor, is the detail that protects the whole building. Tile and grout are not waterproof; the membrane is. Done properly it is a modest cost; skipped, it is the most common cause of the slow, hidden leaks that rot joists and stain ceilings below. Building control's interest in this work is a feature, not a nuisance: an inspected, certified wetroom is one you can prove was built correctly. We build to those standards as a matter of course, photographing concealed waterproofing before tiling so the evidence exists long after the tiles are on.

Building notice vs full plans

When building control is required, you choose between two application routes, and the right one depends on the complexity and risk of the project. A building notice is the lighter route. You notify building control that work is starting, with minimal drawings, and inspectors check compliance on site as the work proceeds. It suits straightforward, smaller works where the approach is well understood, a single structural opening, a bathroom, a window replacement done outside a competent person scheme. The trade-off is that there is no approved design up front, so if an inspector requires a change on site, you carry the cost. The full plans route involves submitting detailed drawings and calculations for approval before work starts. Building control reviews them and issues approval, sometimes with conditions, so you have certainty that the design complies before you build. It suits structural work, extensions, loft conversions and anything where a lender, warranty provider or future buyer will want to see an approved design. Structural engineer's calculations for beams and openings are submitted this way. For most renovations involving structure, we recommend full plans: the certainty of an approved design is worth the modest extra time, and it removes the risk of expensive on-site surprises.

Completion certificates: why they matter at resale

The completion certificate is the document that proves your building work was approved, and its value becomes obvious at exactly the wrong moment if you do not have it: when you try to sell or remortgage. When building control work is finished and the final inspection passes, the local authority or approved inspector issues a completion certificate. For self-certified work, a competent person scheme issues a building regulations compliance certificate instead. Either way, it is your evidence that the work met the regulations. At resale, the buyer's solicitor asks for these certificates for any notifiable work done during your ownership, structural alterations, electrical work, new bathrooms, replacement windows, loft conversions. If they are missing, the sale can stall while you obtain a regularisation certificate retrospectively (which may require opening up finished work for inspection) or take out indemnity insurance, neither of which is quick or free, and both of which weaken your negotiating position. Insurers can also decline claims where unauthorised, non-compliant work contributed to a loss. So the certificate is not paperwork for its own sake; it is a permanent asset attached to the property. Keep every certificate, EIC and compliance document in a project file and hand it to your solicitor at sale. A contractor who delivers that file at handover, as Apex London does, has saved you a future headache.

Frequently Asked Questions

Do I need building regulations approval for a refurbishment?

It depends on the works. Structural alterations, new circuits or electrical work in bathrooms, new drainage, replacement windows, added insulation and wetroom formation all need building control. Purely cosmetic work such as replastering, new kitchen units and redecoration does not. The test is whether the work affects safety or performance.

What is the difference between a building notice and full plans?

A building notice is a lighter route with minimal drawings, where inspectors check compliance on site, suited to simple works. Full plans involves submitting detailed drawings for approval before work starts, giving design certainty up front, and is recommended for structural work, extensions and loft conversions.

Does electrical work in a bathroom need building regulations?

Yes. Electrical work in a bathroom is notifiable under Part P. It must either be carried out by an electrician registered with a competent person scheme such as NICEIC, who self-certifies, or notified to building control in advance so the installation can be inspected and tested. Like-for-like fitting swaps elsewhere are not notifiable.

What happens if I do building work without building regulations approval?

The council can require the work to be opened up, corrected or removed, and the absence of certificates causes problems at resale, where you may need a retrospective regularisation certificate or indemnity insurance. Insurers can also decline claims where non-compliant work contributed to a loss. It is far cheaper to comply from the start.

Why does a completion certificate matter when I sell?

A buyer's solicitor asks for building regulations completion or compliance certificates for any notifiable work done during your ownership. Without them, the sale can stall while you obtain a regularisation certificate or indemnity insurance. The certificate is permanent evidence the work was approved, so keep every certificate in a project file.

Building Regulations for Renovations in London: What You Need