Lawful Development Certificates in London

A lawful development certificate (LDC) is a formal confirmation from the local authority. A certificate of proposed use or development confirms that works you intend to carry out would be lawful as permitted development; a certificate of existing use or development confirms that works already carried out are lawful. Unlike planning permission, an LDC is a legal determination of lawfulness, not a judgement on the merits of a design.

Even where you are confident works are permitted development, a certificate removes doubt — for you, for neighbours, and crucially for a future buyer’s solicitor or a lender. It can also regularise older works whose status is unclear. We assess whether a certificate is appropriate, prepare the precise drawings and evidence an LDC requires, and manage the application.

There are two LDCs and they work differently. A certificate of lawful proposed use or development confirms, before you build, that the works you intend would be lawful — typically as permitted development. A certificate of lawful existing use or development confirms that something already built or in use is lawful, often because it has become immune from enforcement. In both, the burden of proof sits with the applicant, and the council decides on fact and law rather than on the design’s merits, so the case has to be made precisely.

Works carried out without permission are not automatically unlawful forever: they can become immune from enforcement once they have been in place long enough, with the relevant period depending on the type of breach and when it occurred. An existing-use certificate is how that immunity is formally established — but it stands or falls on evidence, such as dated photographs, invoices, statutory declarations, council-tax records and utility bills proving when the works were done. We assess whether the immunity case is realistic and assemble the evidence to support it.

Because an LDC is a determination of fact and law, it is won or lost on accuracy, not persuasion. The drawings must show exactly what is proposed or exists, the application must cite the precise permitted development class and demonstrate compliance with each of its conditions, and any evidence must be unambiguous. Applications fail on technicalities — a measurement over a limit, a missing condition, weak evidence — far more often than on substance. We prepare these to the standard the determination demands, so the certainty you are seeking is actually delivered.

A certificate of lawful proposed development is the route when you intend to build under permitted development and want the council’s written confirmation before work starts. The drawings must show compliance with every limit that applies: depth, height, eaves, materials matching the existing dwelling where required, and cumulative allowances from earlier extensions. A certificate of lawful existing use or development is different: it proves that something already built or a use already operating is lawful, often because enough time has passed for enforcement immunity, or because the works were always permitted. The evidence standard for existing certificates is forensic — dated photos, invoices, statutory declarations and records that prove when works finished.

Mixing the two, or treating an LDC like a mini planning permission, is how applications fail. An LDC does not grant consent for works that need permission; it determines lawfulness on fact and the General Permitted Development Order as it applies to your address.

In principle, many single-storey rear extensions and rear dormers to houses can proceed under permitted development. In practice, London frequently removes or shrinks those rights: conservation areas, Article 4 directions, listed buildings, planning conditions on earlier permissions, and flats or maisonettes that never had householder PD for extensions. Relying on a blog-post size limit without checking the pin is the classic error. We confirm designations and remaining allowance for the specific property, then either prepare a proposed LDC or redirect you to a householder planning application where PD is not available.

Even where PD clearly applies, solicitors on a future sale often ask for proof. A proposed LDC obtained before build is usually cheaper and cleaner than reconstructing an existing-use evidence pack years later when photos and builders’ invoices are missing.

Proposed certificates live or die on precise existing and proposed drawings: floor plans, elevations and sections that demonstrate each PD condition is met, plus a site location plan. Existing certificates need those drawings of what is on site plus a timeline of evidence. Weak measurements, missing earlier extensions on the plan, or a roof volume calculation that does not match the dormer geometry are common reasons for refusal. We prepare LDC drawings to the same accuracy standard as a planning set — because the decision is legal, not aesthetic.

Building regulations still apply to most works confirmed as permitted development. An LDC is not a substitute for building regulations drawings, party wall procedures, or freeholder consent on a flat. We flag the full post-certificate sequence so “lawful” does not get confused with “ready to start on site.”

A refused LDC is not a refusal on merits, because merits were never in play: the council has decided that, on the material in front of it, lawfulness was not demonstrated. That distinction shapes what happens next. Where the failure is technical, such as a drawing that does not evidence a limit or a gap in the timeline for an existing-use case, a fresh application with corrected material is often the pragmatic route. Where the disagreement is genuinely about how the law applies, there is a statutory appeal to the Planning Inspectorate, and because the question is one of fact and law it turns on evidence and interpretation rather than design argument. Our planning appeals work covers this route.

One risk deserves stating plainly. An application for an existing-use certificate puts unauthorised works squarely in front of the council, and a refusal can invite enforcement attention rather than simply leaving things as they were. For existing-use cases the evidential standard is the balance of probabilities, so before submitting we test whether the evidence actually clears it; where it does not, we say so, and discuss whether to gather more or leave the position undisturbed.

A certificate is conclusive only for what is written and drawn on its face. Build a dormer half a metre longer than the certified drawings, or swap materials the description relied on, and the works on site are no longer the works the certificate confirmed, so the protection you paid for falls away precisely when you need it. This is why we treat the certified drawings as a construction constraint, not just an application document, and flag any proposed change on site before it is built.

A proposed certificate also speaks to the law and circumstances as they stood when it was determined. It has no formal expiry date, but if matters relevant to lawfulness materially change before work begins, for instance a new Article 4 direction withdrawing the permitted development right it relied on, the conclusive presumption can be lost for works not yet started. A certificate obtained on false or misleading information can also be revoked. In practice this means starting reasonably promptly once certified, and rechecking the position with us if a long gap opens between certificate and construction, particularly in areas where designations are under review.