Section 192 certificates: confirming lawfulness before you build

A section 192 certificate confirms, before any work starts, that a proposed use or operation would be lawful. It is the only formal way to establish that something is permitted development, and it binds the council. An officer's email saying "that looks like permitted development to you" does not, and it will not satisfy a buyer's solicitor in three years' time.

The application costs a fee and takes eight weeks. Both are small next to the cost of taking down an extension.

What the certificate does

Section 192 of the Town and Country Planning Act 1990 allows anyone who wants to establish whether a proposed use of buildings or land, or proposed operations, would be lawful to apply to the local planning authority for a certificate to that effect.

Lawful means it does not need planning permission, either because it is not development at all or because permission is granted by the General Permitted Development Order. The certificate states that fact, by reference to the plans and description submitted.

Two features make it valuable. It is conclusive, so a certificate granted on an accurate description cannot be undone by a later change of officer or of mind. And it is granted on the facts and the law as they stand at the date of the application.

Its companion, section 191, covers works or uses that already exist and is the route for proving an old extension or a long-standing use. Section 192 is the pre-emptive version, and for a householder planning works it is usually the one that matters.

When it is worth the fee

Not every project needs one. Where the proposal is plainly inside the limits, the fee buys reassurance you may not need.

The cases where it earns its keep are specific.

• The proposal is close to a numerical limit, such as the 4 metre or 3 metre single-storey rear extension depths or the 300 millimetre raised platform threshold.
• The property's permitted development rights may have been removed by condition on an earlier permission, often on an estate built in the last thirty years.
• The site is in a conservation area or an Article 4 direction area, where some rights are restricted and the boundary between restricted and unrestricted is unclear.
• The original dwellinghouse has been extended before, and the cumulative allowance is in doubt.
• A sale, remortgage or lease is in prospect, where a solicitor will ask the question.
• The works involve a garden building whose use might create a separate planning unit, a risk explained in garden offices and the separate planning unit problem.

For householders the most common trigger is the second. An estate-wide condition removing Part 1 rights is easy to miss, and the authority's online planning history is the place to find it.

What to submit

The application is made on the standard form for a lawful development certificate, and the quality of the submission decides the outcome. The authority is answering a legal question about the scheme described, so the description has to be precise enough to answer.

1. A completed application form stating clearly whether the application is for a proposed use, proposed operations, or both.
2. The fee, which for a section 192 application is calculated by reference to the fee that would be payable for a planning application for the same development, so check the current fee schedule.
3. A location plan with the site outlined in red and any other land in the applicant's control outlined in blue.
4. Existing and proposed drawings, dimensioned, at a stated scale.
5. A statement setting out the class of the Order relied on and working through each limitation and condition in turn.
6. Supporting evidence where a factual question arises, such as the extent of the original dwellinghouse or the date of previous extensions.

Point five is what separates a granted certificate from a refusal. The authority is not obliged to construct your argument. Take the class, list its limitations as they appear in the Order, and state the measured position against each one.

Drawings, measurements and the level of detail

Measurements decide these applications, so the drawings have to carry them.

Dimension every figure the class depends on: depth of extension from the original rear wall, height to eaves and to ridge, distance to the boundary where the eaves height limit applies, width of a side extension against the width of the original dwellinghouse, and the area of the curtilage covered by buildings and structures.

Two particular issues cause most refusals.

The first is the original dwellinghouse. Part 1 limits are measured from the original dwelling as built, or as it stood on 1 July 1948, not from the house as it is now. A 1990s conservatory counts against the allowance, so the drawings should show the original footprint distinctly from later additions, with evidence of the dates.

The second is ground level. Height limits are measured from the highest part of the adjacent ground, and on a sloping site the result can differ from the architect's assumption by several hundred millimetres. Show a section with levels. The approach to measuring hard surfaces and ground levels in front gardens, covered in our note on permeable surfaces and Class F, involves the same discipline.

Determination period and the appeal right

The determination period is eight weeks. There is no deemed approval: if the authority does not decide in time, the applicant has a right of appeal against the non-determination rather than a certificate by default.

Refusal, or a certificate granted in different terms from those applied for, can be appealed to the Secretary of State under section 195. The appeal is normally by written representations and the question is one of law and fact rather than planning merits, which makes these appeals narrower and often faster to prepare than a merits appeal.

One point of strategy. A refusal is a public document stating that the authority considers the proposal unlawful, and it sits on the property's planning history. Where the position is borderline and the works are modest, some owners prefer a householder planning application, which asks the council to approve rather than to adjudicate. That is a judgement about appetite for risk, not a rule.

The effect of a later change in the Order

A certificate speaks as at the date of the application, and the Order changes.

Where a certificate has been granted and the relevant class is later amended or withdrawn, the certificate's conclusiveness relates to the lawfulness of the development described at that date. The practical answer is to carry out the works rather than to hold the certificate indefinitely, because a right that no longer exists cannot be revived by a document confirming it once did.

An Article 4 direction made after the certificate is the live risk in conservation areas and in areas under development pressure. Directions are published by the authority, take effect after a notice period, and can remove the very class the certificate relied on.

So treat a section 192 certificate as something to use, not to bank.

Using the certificate on a sale

Conveyancing enquiries on extensions, outbuildings, decking and loft conversions are routine, and the answer "it was permitted development" is only as good as the evidence behind it.

Keep the certificate with the drawings it was granted on, and keep both with the property deeds rather than in a project file. Where the works were built after the certificate, add dated photographs showing the completed works matching the approved drawings, because the certificate covers what was described and the buyer's solicitor will want to see that what was built is the same thing.

Illustrative example: a single-storey rear extension on a semi-detached house, 2.9 metres deep, with a flat roof 2.95 metres high, built 1.8 metres from the boundary. The depth is inside the 3 metre limit for an attached house, the height is inside the 3 metre eaves limit that applies within 2 metres of a boundary, and there is a 1970s rear addition the owner assumed was irrelevant. The certificate turned on measuring from the original rear wall, which the drawings had to show.

A Planning Statement is not required for a certificate application, but a written analysis working through each limitation of the class does the same job and is what most refusals are missing.

Enter your postcode on PlanScope to see which documents your project is likely to need before you submit.

This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it. A lawful development certificate is the only formal way to confirm that works are lawful. PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.