Sometimes. Some house extensions can fall within permitted development rights, but this depends on the proposed work, the property and the applicable conditions and limitations. Other extensions require planning permission.
This page is general information for householders in England. It explains the kinds of facts that affect the planning route. It does not assess a particular house or proposal, and it is not a council determination.
Householder extensions to a dwellinghouse are mainly considered under Class A of the householder permitted-development rules. Class A is the right for enlarging, improving or altering a house. Every limit and condition that applies has to be met. These rights are for dwellinghouses, not flats.
The official technical guidance treats rear and side walls differently, and treats single-storey work differently from two-storey work. How far the extension projects, its height, how close it sits to a boundary or a highway, and how much of the land around the original house would be covered all matter. Materials should be of similar appearance to the existing house, and other conditions can apply — for example to raised platforms, cladding and certain windows.
Existing development counts. Previous extensions and other buildings can use up allowances even if they were built years ago. If the new roof joins the existing house, Class B or Class C may also need to be considered alongside Class A.
The property can change the position even when two proposals look similar. Restricted rights, planning conditions, listing, Article 4 Directions and extra limits on certain designated land can all affect whether permitted development can be relied upon. Those are property-specific facts, not a general rule about every house.
The list below is not a DIY assessment and not a substitute for the official Class A tests. It is a plain-English summary of the kinds of considerations the householder guidance uses.
Some rear extensions of a house may fall within Class A permitted development if every relevant requirement is satisfied. A rear extension is not automatically permitted development.
GOV.UK sets different size limits for how far a rear extension can project, depending on the type of house and whether the work is single-storey. Height, eaves, existing development and remaining garden coverage can all change the position. Wrapping around a corner can bring side-wall limits into play as well as rear-wall limits.
The official guidance also describes a larger single-storey rear-extension process that can involve notifying neighbours. That is not a full planning application, it is not available for every house, and it is not a confirmation that the work is permitted development. Whether that process is relevant depends on the proposal and the property.
For the Class A summary in everyday language, see the permitted development guide.
Side extensions have their own Class A considerations. The exact proposal and the property matter. A side extension is not automatically permitted development, and it is not automatically a planning application either.
The householder guidance treats work beyond a side wall differently from work beyond a rear wall. Height, width relative to the original house, whether the work is single-storey, and where the side elevation sits relative to a highway can all be relevant. Extra Class A limits can apply on article 2(3) land, including to side extensions.
Because a wrap-around extension can engage both rear and side rules, looking only at one elevation is not enough.
Side-wall limits sit alongside the other Class A conditions in the Class A permitted-development explanation.
Some two-storey house extensions can still sit within Class A if the extra limitations and conditions for more-than-one-storey work are met. It is not correct to say that every two-storey extension needs planning permission, and it is not correct to say that a two-storey extension is automatically permitted development.
Two-storey work has additional limits compared with a single-storey extension, including on roof form and windows in a side elevation. Distance from the boundary opposite a rear wall can also matter. On article 2(3) land, Class A has extra restrictions on some more-than-one-storey rear extensions.
The planning route depends on the full proposal, the original house, existing development and any restrictions that apply to the property.
Planning permission may be required where the proposal does not fall within permitted-development rights, or where relevant restrictions or conditions mean those rights cannot be relied upon.
Permitted development is a national right to carry out specified development without a planning application, where the relevant limitations and conditions are satisfied. It is not a guarantee that a local planning authority would grant planning permission if an application were made, and it is not the same as the council confirming that the work is lawful.
Some properties have restrictions that affect householder permitted-development rights. Those restrictions have to be identified from the property, not assumed from the type of extension.
A local planning authority can remove specified rights by making an Article 4 Direction. A previous planning permission can include conditions that remove or limit those rights. Listing can change how permitted development works; it does not automatically mean every piece of work needs planning permission. Listed building consent is a separate consent and can still apply even where a planning application is not required.
Conservation areas, National Parks, National Landscapes, the Broads and World Heritage Sites can carry extra Class A limits. Extra limits are not the same as saying that no house extension is possible, or that permitted development never applies. Whether a particular restriction applies is a property-specific question.
Property-specific facts such as planning history and constraints are what Property & Planning Research is for.
General information is useful for understanding the rules. It cannot replace a look at the actual house and the actual proposal.
The permitted-development guide explains householder Classes A to E in everyday language, including the Class A considerations that apply to many house extensions. It is general information. It does not assess your project.
Read the free permitted-development guide.
The Permitted Development Check is a project- and property-specific check. It considers the relevant permitted-development considerations based on the information you provide. It is not a Lawful Development Certificate, not a council determination, and not legal advice. It does not constitute a council determination, it does not guarantee permitted development, and it does not predict planning approval.
Where a proposal needs a planning application, Verilio’s £99 Planning Preparation service can help with property and planning research, project information, supporting information, and planning documents where they are appropriate to the project.
That can include a Planning Statement where appropriate, and a Design and Access Statement where appropriate. Not every application needs all of those documents. Verilio prepares supporting documents where they are relevant; it does not independently decide the legal requirement, and it does not submit the application.
See the Planning Statement guide and the Design and Access Statement guide for what those documents are. The Planning Preparation package includes property research and document preparation together.
Planning Preparation — £99No. Some house extensions may fall within permitted development if all relevant Class A conditions and limitations are satisfied. Others require a planning application. The answer depends on the work, the house and any restrictions that apply. This page cannot decide that for a particular proposal.
Yes, some house extensions can be permitted development under Class A. That is only where every applicable limit and condition is met, and where the rights have not been restricted for the property. Permitted development is not a blanket rule for any house extension.
Sometimes. Some rear extensions may be permitted development if the relevant Class A requirements are satisfied. Projection, height, existing development, remaining garden coverage and other conditions can all matter. A rear extension is not automatically permitted development.
Sometimes. Side extensions have their own Class A considerations, and extra limits can apply on certain designated land. The exact proposal and the property decide the route. This page does not classify a particular side extension.
It depends. Two-storey work has additional Class A limitations compared with a single-storey extension. Some two-storey extensions can still fall within permitted development if those extra requirements and any property restrictions are satisfied. Others need planning permission.
Then a proposal that might otherwise have been permitted development may need a planning application instead. Restrictions can include Article 4 Directions, planning conditions, listing and extra limits on certain designated land. They have to be identified for the property. They are not assumed from the type of extension alone.
The planning information on this page is drawn from national GOV.UK householder guidance. It applies to householder permitted development and planning applications in England. It is not a determination of a particular extension.
Permitted development rights for householders: technical guidance (GOV.UK). Official householder permitted-development technical guidance for England. Class A covers enlarging, improving or altering a dwellinghouse, including many rear and side extensions. The guidance sets the conditions and limitations; this page does not restate every measurement as if it were a complete legal test.
Making an application (GOV.UK). National guidance on submitting a planning application in England, including supporting information. Use this when a proposal is being prepared as a planning application rather than as permitted development.