What permitted development means
Permitted development is a national grant of planning permission for certain types of work, subject to conditions. It is not a blanket right to extend every home, and the fact that a neighbour has built an extension does not establish that the same design is allowed for your property. The details of the house, its previous extensions, its location and any planning restrictions all matter.
The rules can change and can be interpreted in light of the specific site. Use current government planning guidance as a starting point, then check with the local planning authority. If certainty is important, ask the council about formal confirmation before committing to construction. This page is a general summary for England, not legal advice.
Single-storey rear extensions: common limits
Under the standard householder rules, a single-storey rear extension may generally project up to four metres beyond the rear wall of a detached house, or three metres for any other house. A larger projection may be possible through the prior approval process known as the larger home extension prior approval route, which has its own notification and neighbour consultation requirements. Do not treat that route as automatic permission: the process must be followed and the council's response matters.
The extension's maximum height is generally four metres for a single-storey rear extension. Where it is within two metres of a boundary, the eaves height is limited to three metres. Additional conditions govern materials, roof form, side extensions, the proportion of the plot covered and other details. Measure from the relevant original house wall and established ground level in accordance with current guidance, not from an assumption based on a sketch.
Side extensions and boundary position
A single-storey side extension is generally restricted to a maximum height of four metres and must be no more than half the width of the original house. It also needs to meet other limitations, including position and any applicable rules about the boundary and roof. A side extension that looks modest can still fall outside the permitted development rules if it is forward of a relevant elevation or if earlier development has used up the allowance.
Where a side extension is combined with a rear extension, the proposal needs to be assessed as a whole. Drawings should show the original house, the proposed footprint, boundary distances and finished heights. Ask the council to confirm which dimensions and rules apply to the exact arrangement.
Extensions and renovations
- House extensions and renovations
- Assessing the property and discussing priorities
- Agreeing a clear scope before work starts
Verandas, balconies and raised platforms
A veranda, balcony or raised platform is not interchangeable with an ordinary extension for planning purposes. Permitted development rights do not generally allow a veranda, balcony or raised platform, so a planning application may be needed. Decking and platforms can have separate restrictions, and adding a roof or raised structure can change how a proposal is assessed. Check before building rather than relying on a contractor's description of the feature.
Privacy and overlooking can be important considerations for elevated areas. The council can explain the relevant planning route and whether other controls apply. If a design includes a covered terrace, open-sided structure or substantial glazing, describe the complete proposal rather than asking about just one element.
Conservation areas, Article 4 and other restrictions
Permitted development rights can be restricted or removed. In conservation areas, National Parks, the Broads and other designated land, additional limitations may apply, particularly to extensions at the side or front of a house. Listed building status brings separate controls, and listed building consent may be needed even where planning permission is not. An Article 4 direction can remove specified permitted development rights in a defined area.
Previous planning permissions may also include conditions that limit future extensions. Flats and maisonettes do not have the same householder permitted development rights as a single dwelling house. These are reasons to check with your council using the property address and proposed drawings, rather than relying on a general online summary.
Planning permission is not building regulations
Even if an extension is permitted development, building regulations may still apply. They deal with matters such as structural safety, foundations, fire safety, insulation, ventilation, drainage and energy performance. Some work may be exempt, but that depends on its scope and circumstances; do not assume planning status removes the need to consider building control.
There may also be separate matters such as party wall procedures, boundaries, access, drainage connections and covenants or ownership restrictions. These are not resolved by permitted development rights. Ask the relevant professionals and authorities about the requirements for your project before construction.
A practical check before you design
Gather the property address, a site plan, existing and proposed elevations, dimensions from the original rear wall, heights, boundary distances and photographs. Explain whether the home has been extended before and whether it is listed or in a designated area. The council can advise what information it needs and whether a formal application or prior approval process is relevant.
Once you understand the planning route, a design can balance room size, daylight, garden space and construction practicality. Our single-storey extensions page explains the service; the house extension cost guide discusses cost factors. For broader work, see extensions and renovations or garage conversions, and use the contact page to discuss the building work.
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Frequently asked questions
Can I build a single-storey extension without planning permission?
Some proposals fall within permitted development, but only if all relevant limits and conditions are met and the rights have not been restricted. Check the specific proposal with your council before starting.
What is the maximum size of a permitted rear extension?
The standard limits commonly allow a rear projection up to four metres for a detached house and three metres for another house; a larger home extension route may be available subject to prior approval. Other height, position and site conditions also apply.
Does permitted development mean building regulations do not apply?
No. Planning permission and building regulations are separate controls. An extension may still need building regulations approval even where it is permitted development.
Can a veranda be permitted development?
A veranda, balcony or raised platform is generally not covered by the usual householder permitted development rights. Ask your council whether planning permission is required for the specific design.
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