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semi detached permitted development

Semi-Detached Permitted Development: What You Can Build in England

What permitted development lets you build on a semi-detached house in England: 3m and 6m rear limits, height rules, neighbour consultation, Article 4 and next steps.

The Extension Works 9 November 2026
Semi-Detached Permitted Development: What You Can Build in England

Semi-Detached Permitted Development: What You Can Build in England

Single-storey rear extension on a semi-detached house

If you own a semi-detached house in England, you can usually build a single-storey rear extension up to 3 metres deep without a planning application. With the neighbour consultation scheme, you can go up to 6 metres. Both routes depend on your house keeping its rights and on the extension meeting every limit in the rules. This guide explains the limits, how to check your rights and how the process works.

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TL;DR

  • A single-storey rear extension on a semi-detached house can extend up to 3 metres from the original rear wall under the standard permitted development limit, according to GOV.UK technical guidance.
  • Between 3 and 6 metres, you must go through the neighbour consultation scheme, and work cannot start until the council responds or 42 days pass without a decision.
  • The extension must not exceed 4 metres in height, and other limits cover eaves, width and how much land you build on.
  • Conservation areas, listed buildings, Article 4 directions and conditions on earlier permissions can remove your rights. Check before you pay for drawings.
  • A Certificate of Lawful Development gives formal confirmation that your plans are permitted development.

Table of Contents

What permitted development means for a semi-detached house

Permitted development (PD) is a national grant of planning permission. If your extension meets the limits and conditions of the relevant Class, you don’t need to submit a full planning application. GOV.UK’s guidance stresses that you must consider the rules as a whole. Meeting the depth limit while breaking the height limit still means you need permission.

Semi-detached homes sit in the middle of the PD rules. The standard rear depth limit is 4 metres for a detached house and 3 metres for any other house, which includes semi-detached and terraced homes. The larger limit is 8 metres for detached and 6 metres for the rest.

Rear extension depth limits by house type

These rules apply in England. Planning is devolved, and Wales and Scotland have their own versions. In Scotland, for example, the single-storey extension limit is 3 metres for terraced houses and 4 metres for other houses. Don’t use a Scottish or Welsh figure for an English house.

How to check your semi-detached house has permitted development rights

Most semi-detached houses have PD rights by default. They are lost in a handful of situations, so check these before you commission anything.

Is the house a single dwellinghouse?

PD for householders applies to houses, not flats or maisonettes. If your semi-detached property has been converted into flats, these rights don’t apply in the same way.

Is it in a protected area or listed?

The House of Commons Library explains that PD may be restricted in protected areas, conservation areas and for listed buildings. Haringey Council also states that a rear extension is permitted development only if the property is not in a conservation area or a listed building. The larger 6 metre limit is also not available on Article 2(3) land or sites of special scientific interest.

Is there an Article 4 direction?

An Article 4 direction means planning permission is needed for development that would otherwise be permitted. North Somerset Council notes that these directions can remove rights for extensions, porches, replacement windows and doors, or painting the exterior. Your local council’s planning pages normally show where they apply.

Was PD removed by a condition?

Milton Keynes City Council points out that rights can be withdrawn by a condition on a previous planning permission. This is common on newer estates. Look at the original planning decision for your house, which is often on the council’s online planning register.

Do you want it in writing?

For formal confirmation, you can apply for a Certificate of Lawful Development. Oxford City Council advises this route when you want proof that your proposal falls under PD. It is useful when you later sell and a buyer’s solicitor asks for evidence.

The size limits for a semi-detached rear extension

The technical guidance sets out the core limits for a single-storey rear extension on a semi-detached house:

Limit Standard route Larger route (neighbour consultation)
Depth beyond original rear wall Up to 3 metres More than 3 metres, up to 6 metres
Maximum height 4 metres 4 metres
Process No application to the council Notify the council, neighbours consulted
Where available Most houses with PD rights Not on Article 2(3) land or SSSIs

Source for depth and height: GOV.UK technical guidance.

A few points catch people out.

Depth is measured from the original rear wall. “Original” means the house as first built or as it stood on 1 July 1948. If a previous owner added a rear extension, it may already use part of your allowance. Our guide to how big a rear extension can be under permitted development goes through the measuring in more detail.

Height has its own rules. The extension can’t exceed 4 metres in height, and the guidance also limits eaves height where the extension comes within 2 metres of a boundary. North Somerset Council also notes that height is compared with the existing roof and eaves. Our article on permitted development height limits covers how to measure it.

You can’t cover more than half the land around the house. The same council states that rights are not available if an extension would cover more than half the area of land around the original house. Outbuildings, sheds and earlier extensions all count towards this.

Side and wrap-around extensions are different. Side extensions have a width limit, and where an extension fills the area between rear and side walls, both sets of restrictions apply. A wrap-around on a semi-detached house is rarely straightforward under PD, so get it checked before you plan around it.

Going beyond 3 metres: the neighbour consultation scheme

For a semi-detached house, an extension of more than 3 metres and under 6 metres falls under the neighbour consultation scheme. The process, as described in the technical guidance, is:

  1. You notify the local planning authority of the proposal.
  2. The council gives neighbours notice and a chance to object.
  3. Work cannot start until the council tells you no prior approval is required, grants prior approval, or 42 days pass without a decision.

This is a prior approval process, not a full application. The House of Commons Library explains that it lets the council assess whether the works meet the conditions in the General Permitted Development Order, and it does not reopen the principle of the development.

Neighbours matter more in a semi-detached house, because one of them shares your party wall. An objection from the adjoining owner is the most likely to be considered, since the impact on their light and outlook is what the council assesses. Our article on whether the neighbour consultation scheme applies to your extension explains how this works in practice.

Some councils describe the 3 to 6 metre range as needing a notification, with no notification needed at 3 metres or less for semi-detached homes, as North Somerset’s rear extension page sets out. Your own council’s pages tell you how it handles submissions.

Should you go for 3 metres or 6 metres?

The longer extension looks attractive, but depth alone doesn’t decide the right size. Think about three things.

  • Your garden. Deep extensions take garden space, and the half-the-land rule still applies.
  • Your neighbours. A 6 metre extension against a shared boundary affects the adjoining house more than a 3 metre one. A conversation before the notification often avoids objections.
  • How you use the room. A kitchen-diner usually needs less depth than people assume once the layout is planned well. A 3D model shows this quickly.

Perspective

We built our service around one frustration: homeowners on semi-detached streets wait weeks for quotes, then discover the planning route only after paying for drawings. A semi-detached house is the most common starting point for a rear extension, and the PD rules are workable once someone checks them against your actual house.

That is why we put the planning check inside the service. We handle Permitted Development and prior-approval routes ourselves, alongside architectural plans, structural calculations and building control management, so the design is drawn to the limits that apply to your house from day one. You see the extension in live 3D, you get a fixed VAT-inclusive price, and the same in-house team carries the project from first sketch to final sign-off.

Our view is simple. The depth you can build should be settled before the design, not after it. The earlier the route is clear, the fewer surprises you have.

Esskay

A practical checklist before you commission drawings

  1. Confirm the house type. It should be a single house, not converted into flats.
  2. Check for a conservation area, listing or Article 4 direction on your council’s planning map or by asking the planning team.
  3. Read the original planning permission for conditions removing PD rights, especially on newer estates.
  4. Measure from the original rear wall, and note any existing extensions or outbuildings.
  5. Check height and eaves against the 4 metre limit and the boundary rule.
  6. Choose the route. Up to 3 metres is the standard PD route. Beyond that, plan for the neighbour consultation scheme and its 42 day period.
  7. Decide whether you want a Certificate of Lawful Development as written proof.
  8. Plan for the other approvals. PD deals with planning only, and building work usually has other requirements too. The Scottish government warns that other approvals may still be needed even when you meet PD rules, and the same principle is sensible to apply in England. We manage building control as part of our service.

For a longer version with measuring advice, see our step-by-step checklist before you commission drawings, and our notes on what homeowners consistently get wrong about permitted development.

Common mistakes on semi-detached houses

Assuming the neighbour’s extension sets a precedent. Your neighbour may have used planning permission, a different route or different rights. Your own house is assessed on its own facts.

Counting from the current back wall. If the house already has a rear addition, the 3 metre or 6 metre measurement still starts from the original wall.

Forgetting the combined effect of limits. Height, eaves, coverage and depth all have to be met together. Our guide to the original house rule and the 50% coverage limit shows how they interact.

Starting before the 42 days are up. On the larger route, building before the council has responded or the period has passed puts the whole project at risk.

Using figures from another part of the UK. Scottish and Welsh limits differ. In Wales, for instance, no extension can be built in front of the principal elevation and none can cover more than half the land around the original house. Always check the country first.

Common mistakes on semi-detached houses

How we handle a semi-detached extension

Our service is for homeowners who want a single-storey rear extension without a long sales process. You get an instant online quote, a live 3D model of your extension and a fixed VAT-inclusive price. There are no sales visits. One dedicated in-house team looks after design, planning (including Permitted Development and prior-approval routes), architectural plans, structural calculations, project management and construction. Your work comes with a 12-month workmanship warranty.

To book, there is a one-off booking fee of £499, set out on our how it works page. Payment for the build itself is by deposit and staged payments.

The Extension Works

If you own a semi-detached house in our area and want to see what a rear extension could look like, try the instant extension quote tool. You can also read about our single-storey rear extension service.

FAQ

How far can I extend a semi-detached house without planning permission?

Under the standard PD limit you can extend up to 3 metres beyond the original rear wall. With the neighbour consultation scheme, the limit rises to 6 metres outside Article 2(3) land and sites of special scientific interest. The height limit is 4 metres in both cases, per the GOV.UK guidance.

Do I need to tell my neighbours about a 6 metre extension?

Yes. You notify the council, and the council gives neighbours notice and a chance to object. You can’t start until the council decides or 42 days pass without a decision. Speaking to your adjoining neighbour first usually makes the process smoother.

How do I know if my house still has permitted development rights?

Check whether it is in a conservation area, is listed, sits under an Article 4 direction or has a planning condition removing PD. Your council’s planning pages and the original planning decision should tell you. If you want written confirmation, you can apply for a Certificate of Lawful Development.

Is my semi-detached house treated like a terraced house?

For rear extension depth, yes. Both fall under the 3 metre standard limit and the 6 metre larger limit, while detached houses get 4 and 8 metres. Other rules, such as side extensions, can differ by house type, so confirm which apply to you.

Can I build an extension for £20k?

The cost depends on size, specification and your site, and we don’t publish a price for a rear extension. The quickest way to get a figure for your own house is to use our instant quote tool, which gives a fixed VAT-inclusive price.

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