Permitted Development Advice in London

Permitted development rights allow specified works to houses — some extensions, lofts and outbuildings — to proceed without planning permission, subject to limits on size, height, materials and position. They apply to houses, not flats or maisonettes, and they are frequently restricted in sensitive locations. Even where they apply, you usually still need building regulations approval, and it is often wise to confirm the position with a lawful development certificate.

In conservation areas, permitted development is often reduced, and an Article 4 direction can remove specified rights entirely. Listed buildings, flats and maisonettes, and properties with planning conditions are also restricted. We assess your specific property rather than relying on general rules, and advise whether to proceed under permitted development, seek a certificate, or apply for planning permission.

For a house, permitted development broadly covers single-storey rear extensions within set depth limits (with larger rear extensions possible under the prior-approval route); single-storey side extensions within width and height limits; roof additions such as rear dormers within a set volume allowance; outbuildings; and hardstanding. Each comes with detailed conditions on height, materials and position, and the allowance is cumulative — earlier extensions count against it. The specific depth and volume figures for each class are set out in our guide to permitted development explained; we confirm exactly what remains available on your property.

Some of the most useful rights, such as the larger single-storey rear extension, are not pure permitted development but require prior approval: you notify the council, which consults your immediate neighbours, and if they do not object on specified grounds the works can proceed. It is faster and more certain than a full application but is not automatic, and it only assesses limited matters. We advise when prior approval is the right route and manage the notification, so you use the allowance without tripping over its procedure.

Relying on permitted development without documenting it is a quiet risk: at sale, a buyer’s solicitor or lender will often ask for proof that works did not need permission, and an undocumented assumption can stall a transaction. A lawful development certificate is the council’s formal confirmation that the works are lawful, and we generally recommend obtaining one where a project relies on permitted development, so the position is settled in writing rather than argued years later.

PD is not a vibe; it is a legal envelope. We check tenure, designations, planning conditions and cumulative extensions before advising that a rear extension or dormer is permitted. Wrong advice here creates enforcement and sale problems years later.

Larger home rear extensions may use prior approval rather than pure PD. We explain when neighbour consultation applies and what that process does and does not assess.

Even where PD applies, a lawful development certificate is often the wise next step so lawfulness is proven in writing. Buyers’ solicitors and lenders frequently ask for it. We prepare drawings to the precision a determination requires.

Building regulations still apply to most PD works. Planning freedom is not a free pass on structure, fire or insulation.

If the design you need exceeds PD, forcing a cramped PD scheme can destroy the brief. A well-designed householder application is often better value than a compromised box that happens to fit a limit. We present both options with risks, not a single sales route.

Article 4 streets should assume tighter control until proven otherwise.

Every allowance is measured against the original house: the dwelling as first built, or as it stood at the historic date the legislation fixes, not the building you happen to own today. A rear addition built by an owner three sales ago still consumes the allowance, and a side projection added before anyone kept good records may count too. This is where confident assumptions most often collapse: the house looks unextended to its current owner, while the planning history quietly says otherwise.

Because a lawful development certificate is determined against evidence, we treat the baseline as something to be proven rather than assumed. In practice that means reading the council's planning history for the address, comparing historic mapping and any surviving drawings, and measuring what actually stands today, so the remaining allowance is calculated from facts. Where the record is thin we say so, and explain how much weight the position will bear before you commit to works. Buyers weighing a purchase on assumed rights face the same question a step earlier, which is why we offer pre-purchase planning advice before contracts are exchanged.

The headline size limits are the part everyone checks. In our experience it is the smaller conditions attached to each class that catch schemes: external materials generally need to be of similar appearance to the existing house, eaves height limits tighten close to a boundary, a rear dormer must normally sit below the ridge and back from the eaves, and verandas, balconies and raised platforms fall outside the rights altogether. A flue, a parapet, a rooflight upstand or a raised deck can each carry otherwise compliant works over the line.

This is precisely what an officer assesses on a certificate application: not whether the design is attractive, but whether every dimension and detail sits inside the conditions as drawn and described. There is no planning judgement to appeal to and no discretion to invoke; the works either fit the wording or they do not. We design to the envelope from the first sketch rather than trimming a finished design afterwards, and where a single detail cannot comply we look first at adjusting that detail, since one balcony or one high parapet should not force the whole project into a householder planning application it did not otherwise need.

Permitted development answers one question only: whether the works need planning permission. It says nothing about the other permissions attached to the property. Works on or near a shared boundary can require party wall notices, which run statutory periods of one or two months depending on the notice, and a neighbour can dissent and appoint a surveyor however lawful the scheme is in planning terms. Restrictive covenants on the title can prohibit what the planning system would allow, and on estate-managed streets a separate consent regime often applies with its own criteria and timetable, which is where estate and freeholder consents come in.

A house held on a lease may also need the freeholder's approval, commonly formalised through a licence to alter, and building over or close to a public sewer usually needs the water company's agreement before work starts. None of these bodies is bound by the council's view, and each runs to its own clock. We flag the full set at the assessment stage, so a project that is lawful in planning terms does not stall later against a consent nobody had listed.