In 2013, the government quietly did something extraordinary. It doubled the permitted depth of single-storey rear extensions under Class A permitted development rights. Instead of the traditional three metres, homeowners were suddenly allowed to build six metres on a terraced or semi-detached house, and eight metres on a detached house.
For most councils, this felt like planning law on steroids.
For decades, anything beyond three or four metres would usually have been refused on amenity grounds. Then, overnight, Parliament decided that much deeper extensions should be allowed as permitted development, subject only to a light-touch process known as prior approval.
That change remains one of the most commercially significant shifts in householder planning in the last twenty years.
What is a larger home extension?
Under the standard Class A rules, you can extend three metres from the original rear wall (four metres if detached). The “larger home extension” provisions allow you to go up to six metres (terraced/semi) or eight metres (detached).
This is not a planning application. It is not a design assessment. It is not an opportunity for the council to apply its usual policies.
It is a prior approval application under what is known as the Neighbour Consultation Scheme.
You submit a short form, a block plan, and the fee (currently £240). The council writes to adjoining neighbours. If no neighbour objects within the consultation period, the council must confirm that prior approval is not required. In other words, you are automatically entitled to build.
The council has no discretion at that stage.
Where it goes wrong
The problems begin when a neighbour objects.
If even one adjoining neighbour raises an objection, the council is suddenly empowered to assess the proposal — but only in terms of its impact on the amenity of adjoining neighbours. It cannot assess design. It cannot assess parking. It cannot assess character. It cannot refuse it because it “looks too big”.
It can only assess neighbour impact — typically loss of light or an overbearing sense of enclosure.
In theory, that is a narrow and controlled test.
In practice, many councils treat it as an opportunity to refuse six-metre extensions because they do not like them.
I say that having worked in local authority planning myself when these rules were introduced. Planners were taken aback. Six-metre extensions felt excessive. Eight metres felt outrageous. Historically, such schemes would almost always have been refused.
But that is not the legal test.
The permitted development right allows that depth. The council’s job is not to decide whether six metres is attractive. It is to decide whether it causes unacceptable harm to neighbours. That’s an important difference!
A high appeal success rate
In my experience, councils routinely refuse larger home extensions once a neighbour objects. It is almost automatic in some boroughs. The refusal wording is usually about “overbearing impact” or “loss of outlook”.
Appeal inspectors, however, apply the legislation properly.
Inspectors understand that Parliament deliberately allowed six and eight metre extensions. They do not approach these cases with the same historic hostility that some councils still exhibit.
The result is a high success rate at appeal. In fact, our highest success rate at appeal is for these kinds of development – we win more appeals for larger home extensions that we do for anything else.
So, if your six-metre extension has been refused, you should not assume the council is right.
The power (and randomness) of neighbour objections
The Neighbour Consultation Scheme creates an unusual dynamic. Whether you can build often depends on whether a neighbour decides to send an email.
On many streets, one house builds a six-metre extension without difficulty because no one objects. A near-identical house nearby is refused because a neighbour objected and triggered the council’s assessment powers.
The difference is not planning merit. It is timing and human behaviour.
In my experience, most larger home extension proposals attract no objections at all and proceed without difficulty. Neighbours are often tolerant. But when objections are made, the council’s response can be disproportionate. That is where appeals come in.
Some important practical points
Larger home extensions are not permitted development on Article 2(3) land, including conservation areas. In those locations, the original depth limits apply.
You must not start work before prior approval has been granted. If foundations have been dug before the decision is issued, the application must be refused. This is different from a normal planning application, where development can be started at your own risk.
And, although the planning rules allow six or eight metres, good design still matters. A six-metre room is not automatically a good room. Bigger is not always better. But that is a design discussion — not a reason for councils to refuse prior approval under the wrong test.
Refused? Consider an appeal
If you have been refused prior approval for a larger home extension, do not assume that is the end of the road.
Many councils still approach these applications as if they were ordinary planning applications. They are not. The legal framework is different, and inspectors are often much more measured and pragmatic.
We specialise in planning appeals and have a strong track record of overturning refusals for six- and eight-metre extensions.
Here are some examples of ourrecent larger home extension appeals:
- Appeal allowed in Ealing – 9 Currey Road
- Another appeal allowed in Ealing – 42 Dordrecht Road
- Appeal allowed in Waltham Forest – Millfield Avenue
- Another appeal allowed in Waltham Forest – 95 Sinclair Road
- Appeal allowed in Redbridge – 331 Stradbroke Grove
- Another appeal allowed in Redbridge – 324 Cranbrook Road
If your larger home extension has been refused, send us the decision notice and we will give you clear, honest advice on your chances of success at appeal.
