Planning Feasibility Studies in London

Property decisions in London are often made on assumptions about what can be done — an extension, a loft, a basement, a change of layout — that have never been tested against planning policy. A feasibility study replaces those assumptions with evidence: the property’s planning history, its conservation and listing status, any Article 4 directions, and a realistic view of what the local authority is likely to support. For buyers, it can be the difference between a sound purchase and an expensive mistake.

We test a small number of options against the constraints and your objectives, and set out the likely planning route, the risks, and what evidence or pre-application advice might strengthen a future case. The result is a clear basis for deciding whether and how to proceed, before you spend on a full design.

A worthwhile feasibility study builds a clear picture of the property’s real constraints and opportunities. We check its planning history and any earlier refusals, its designations — conservation area, listing, Article 4 directions, tree preservation orders — and the relevant local plan policy, then test that against daylight and neighbour-amenity considerations and the physical capacity of the building itself. The output is not a vague reassurance but an evidenced map of what is likely to be supported, what is borderline, and what is a non-starter.

The most valuable time for a feasibility study is often before exchange. Many London homes are bought for their potential, and that potential varies enormously with constraints that are invisible on a viewing — a listing, a restrictive Article 4 direction, a recent refusal next door, or a lease that limits what a flat can do. A short pre-purchase appraisal tells you whether your plans are realistic before you commit, and frequently informs the price worth paying or the terms worth negotiating.

A feasibility study earns its keep by turning into a route. From the assessment we recommend the right mechanism — permitted development with a lawful development certificate, a householder or full application, or a pre-application enquiry first on a sensitive site — and the order in which to tackle things, including any phasing. You then move into design with a tested strategy rather than an assumption, which is the single biggest way to avoid wasted fees and a refusal.

Feasibility pulls planning history, conservation and listing status, Article 4 directions, trees, flood risk flags and the relevant local plan themes that will shape an officer’s view. We then test a small number of options against neighbour amenity and host character so you see what is likely, borderline or unrealistic.

For buyers, this work often sits before exchange. Paying for certainty on a dream extension is cheaper than discovering a refusal risk after you own the keys.

A good study ends with a recommended route: permitted development and LDC, householder application, pre-application advice first, or walk away. It should also list evidence you will need later — heritage statement, tree survey, basement impact assessment — so fees are sequenced correctly.

We can then move into design and planning drawings on a foundation that has already been stress-tested.

It is not a full design service, not a guarantee of permission, and not a substitute for a measured survey when drawings are required. It is the decision tool that stops the wrong project starting. We keep the output written and specific to the address rather than a generic London checklist.

Where the property is leasehold, freeholder constraints sit beside public planning and are flagged early.

The planning history is the closest thing a property has to a track record, and reading it properly takes more than counting approvals. A refusal matters less than the reasons behind it: a scheme turned down on scale can often return smaller, while one refused on principle rarely can. Conditions on old permissions deserve equal attention, because some remove permitted development rights entirely, and a property that looks like a straightforward candidate for a rear extension may in fact need a full application for work its neighbours did without one. Lapsed permissions, part-implemented schemes and any enforcement history each shift the picture again.

Neighbouring history is useful but weaker evidence than most buyers assume. Every application is decided on its own merits, so an approval two doors down is an indication rather than an entitlement; policy may have changed since, or the two properties may differ in ways that mattered to the officer. Appeal decisions are often the most instructive documents of all, because an inspector's reasoning sets out what actually decided the case. We weigh all of this rather than reporting a bare list of references.

Flats change the feasibility question fundamentally, because householder permitted development rights apply to houses and not to flats. Extensions, roof alterations and most external changes to a flat therefore need a full planning application, and the informal fallback a house enjoys simply is not there. Ownership boundaries matter just as much: the roof space above a top-floor flat, or the garden behind a ground-floor one, may not be within the lease's demise at all, and no planning permission can overcome that.

The lease then adds a private layer of consent that sits entirely apart from the council. Most leases require the freeholder's approval for structural or external alterations, often formalised through a licence to alter, and on managed estates there may be scheme-wide rules as well. A feasibility study for a flat therefore reads the lease position alongside planning policy, flags where freeholder consent is likely to be needed, and gives an honest view of which of the two hurdles is the harder one. It is common for planning to be achievable while the lease makes the project impractical, and far better to know that first.

Not every study ends in a clean yes or no, and the honest ones say so. Where a proposal sits in the borderline band, we set out how to reduce the uncertainty rather than leaving you with a shrug. The usual first step is pre-application advice: a written officer view on the specific scheme, which is informal and does not bind the eventual decision, but reliably reveals which issues the case will turn on and whether the principle is worth pursuing.

The other tool is the fallback position. Where part of what you want could be built under permitted development, establishing that route, ideally with a lawful development certificate, can be a material consideration when a fuller application is judged, because the comparison is then with what could be built anyway rather than with the site as it stands. Sometimes the right answer is simply to trim the scheme to the version the evidence supports and secure a consent, leaving the more ambitious move for a later application. The study's job is to rank these paths by cost, time and risk so the choice is yours to make on evidence.