Usually not. National policy asks for a planning statement only with major development, and a house extension needs one only if your council's local validation list asks for it or the site's history makes the case hard to read from drawings alone. When one does help, ours is from £295, and we check your council's list before we quote.
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So the useful question is not whether a statement is allowed. It is whether the officer needs an argument that the plans cannot make for themselves.
What does national policy actually require?
For major development, a concise planning statement. For everything else, only the minimum information needed to reach a decision. Both come from policy DM1 of the August 2026 Framework (NPPF chapter 3).
Major development is defined in law. It includes 10 or more new homes, or a building that creates 1,000 square metres or more of floor space (DMPO 2015, article 2). A rear extension, a side return infill or a two-storey side addition is nowhere near either line, so the national requirement does not reach it. A householder application normally goes in with the form, the drawings, a location plan and the fee.
When can my council insist on one?
Only through its published local validation list, and only within two limits. The Framework says a local list should add an information requirement only where a policy in the development plan calls for that further assessment (NPPF policy DM2). The government's guidance adds that anything requested must be reasonable for the nature and scale of the scheme (Making an application).
London boroughs draw that line in different places, and they revise their lists. That is why we read your council's current list for householder applications before quoting. If it does not ask for a statement and nothing about the site is contentious, we tell you so and you do not pay for one.
Is it the same as a design and access statement?
No. A design and access statement explains the design and how people get into and around the building. A planning statement argues the scheme against planning policy. People are often asked for "a statement" and are not sure which.
For a house extension the law asks for one in two cases only. The planning application needs one where the site is in a conservation area or World Heritage Site and the scheme creates 100 square metres or more of floor space or a new home (DMPO 2015, article 9). And if the house is listed, the listed building consent application needs one too (Making an application). A smaller extension in a conservation area more often needs a heritage statement, which deals with the effect on the area's character. Where one is needed, our design and access statement is a separate fee, and what a design and access statement costs sets it out.
When is a statement worth paying for anyway?
In three cases, even where the list does not demand one.
After a refusal. The officer will read your new scheme against the reasons on the old decision notice. A short statement that sets each reason beside the change that answers it does that comparison for them and shows the redesign was deliberate. The drawing side of that job is covered in who can redraw my plans after a refusal. If you think the refused scheme was right as drawn, the route is a householder appeal instead, handled by our sister practice DrawingsDirect. You can appeal for up to 12 weeks from the date on the decision letter (GOV.UK).
On a retrospective application. The law lets a council grant permission for development carried out before the date of the application (TCPA 1990, section 73A). The statement says plainly what was built, when, and how it differs from anything approved, then makes the policy case. "It is finished now" carries no weight, so it should not be the argument. Our retrospective application includes the as-built drawings that go with it.
Where the scheme departs from a design guide. If your extension is deeper or taller than the borough's guide suggests, a page explaining why it still protects the neighbours' light and outlook gives the officer something to cite in the report.
What goes into a householder planning statement?
Less than people expect. The site and the proposal, then the three or four policies that decide the case, from the London Plan, your borough's local plan and any design guide. Then one heading per issue the officer will weigh, such as the neighbours' light and outlook, the character of the street and the garden left behind, each saying what the policy asks and where the drawings show it is met. Listing every policy in the plan does not help anyone.
Our planning statement service is written against the drawings it explains, so the two agree, and it costs from £295. If you have no drawings yet, our complete planning drawing service covers the whole householder application.
Frequently asked questions
Can the council refuse to register my application without a planning statement? Only if its published local list asks for one for that kind of application. A requirement that is not on the list has no bearing on whether the application is valid.
Will a planning statement get my extension approved? No document can promise that. The council decides on the scheme and its policies; a statement makes sure the officer sees the case for it clearly.
How long should it be for an extension? A few pages. It covers the issues the officer will weigh, not every policy in the local plan.
Do I need one for a lawful development certificate? No. A certificate application tests the facts against the permitted development rules, so it needs evidence and drawings, not a policy argument.
