Planning And Building Regulation Guidance For Conservatories, Orangeries And Extensions


This guidance reflects increases to the size limits for single-storey rear extensions which apply between 30 May 2013 and 30 May 2016 and the associated neighbour consultation scheme.

An extension or addition to your house is considered to be permitted development, not requiring an application for planning permission, subject to the following limits and conditions:

  • No more than half the area of land around the “original house”* would be covered by additions or other buildings.
  • No extension forward of the principal elevation or side elevation fronting a highway.
  • No extension to be higher than the highest part of the roof.
  • Single-storey rear extension must not extend beyond the rear wall of the original house* by more than three metres if an attached house or by four metres if a detached house.
  • Also, outside Article 1(5) designated land* and Sites of Special Scientific Interest the limit is increased to 6m if an attached house and 8m if a detached house until 30 May 2016. These increased limits (between 3m and 6m and between 4m and 8m respectively) are subject to the neighbour consultation scheme.
  • The maximum height of a single-storey rear extension of four metres.
  • Extensions of more than one storey must not extend beyond the rear wall of the original house* by more than three metres.
  • Maximum eaves height of an extension within two metres of the boundary of three metres.
  • Maximum eaves and ridge height of extension no higher than existing house.
  • Side extensions to be a single storey with a maximum height of four metres and width no more than half that of the original house.
  • Two-storey extensions are no closer than seven metres to rear boundary.
  • Roof pitch of extensions higher than one storey to match existing house.
  • Materials to be similar in appearance to the existing house.
  • No verandas, balconies or raised platforms.
  • Upper-floor, side-facing windows to be obscure-glazed; any opening to be 1.7m above the floor.
  • On designated land* no permitted development for rear extensions of more than one storey.
  • On designated land no cladding of the exterior.
  • On designated land no side extensions.

* The term “original house” means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.

* Designated land includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.

Further restrictions on permitted development A local planning authority may have removed some permitted development rights by issuing what is known as an Article 4 Direction or may have removed those rights on the original, or any subsequent, planning permission for the house. This will mean a planning application will be needed for development which normally does not need one. Before undertaking any development, checks should be undertaken with the local planning authority to determine whether any restrictions on permitted development have been made.

The remainder of this guidance provides further explanation about the detailed rules covering what improvements can be made to a house and its surroundings as permitted development. In particular, it provides more details on the limits (eg on size) and the conditions that will need to be complied with if development is to take place without the need for an application for planning permission. The guidance covers in detail Classes A-E of the rules which cover common development projects such as extensions, loft conversions, alterations to a roof, porches, and buildings on land surrounding the house. The rules for Classes F-H are included in this document; detailed guidance on them is not included, although cross-references are included to other guidance published by CLG.

You are strongly advised to read a technical guidance document produced by the Government to help understand how permitted development rules might apply to your circumstances.


On 9 May 2013, secondary legislation was laid before Parliament which will increase the size of single-storey rear extensions which can be built under permitted development, and will bring into force the associated neighbour consultation scheme. This draft guidance is issued to provide initial information on how the scheme will work. The Householder Permitted Development: Technical Guidance will be fully updated once the secondary legislation has been approved by Parliament and has come into force.

For three years, between 30 May 2013 and 30 May 2016*, householders will be able to build larger single-storey rear extensions under permitted development. The size limits will double from 4 metres to 8 metres for detached houses, and from 3 metres to 6 metres for all other houses. These new larger extensions (i.e. if they extend between 4 and 8 metres, or between 3 and 6 metres) must go through the following process**.

Please note: the permitted development allowances described here apply to houses not flats, maisonettes or other buildings.

1. A homeowner wishing to build a larger single-storey rear extension must notify the local planning authority and provide:

a. a written description of the proposal which includes the length that the extension extends beyond the

rear wall of the original house, the height at the eaves and the height at the highest point of the


b. a plan of the site, showing the proposed development.

c. the addresses of any adjoining properties, including at the rear.

d. a contact address for the developer and an email address if the developer is happy to receive

correspondence by email. There is no fee in connection with this process.

2. The local authority may ask for further information if it needs it to make a decision about the impact of the development on the amenity of adjoining properties.

3. The local authority will serve a notice on adjoining owners or occupiers, i.e. those who share a boundary, including to the rear. This will give the address of the proposed development and describe it, including the information in 1(a) above. It will also set out: 1 See paragraph A.1(ea) of Class A, Part 1, Schedule 2 of the Town and Country Planning (General Permitted Development) Order 1995, as inserted by the Town and Country Planning (General Permitted Development) (Amendment) (England) Order 2013, available at 2 See paragraph A.4 of Class A, Part 1, Schedule 2 of the Town and Country Planning (General Permitted Development) Order 1995, as inserted by the Town and Country Planning (General Permitted Development) (Amendment) (England) Order 2013, available at LARGER HOME EXTENSIONS: NEIGHBOUR CONSULTATION SCHEME V1.1 a. when the application was received, and when the 42-day determination period ends b. how long neighbours have to make objections (which must be a minimum of 21 days), and the date by which these must be received A copy of this notice must also be sent to the developer.

4. If any adjoining neighbour raises an objection within the 21-day period, the local authority will take this into account and make a decision about whether the impact on the amenity of all adjoining properties is acceptable. No other issues will be considered.

5. The development can go ahead if the local authority notifies the developer in writing either: a. that as no objections were received from adjoining neighbours it has not been necessary to consider the impact on amenity, or b. that following consideration, it has decided that the effect on the amenity of adjoining properties is acceptable.

6. If the local authority does not notify the developer of its decision within the 42-day determination period, the development may go ahead.

7. If approval is refused, the developer may appeal.

8. The extension must be built in accordance with the details approved by the local authority (or, if no objections were raised or the local authority has not notified the developer of its decision, the details submitted), unless the local authority agrees any changes in writing.

9. The development must accord with all other relevant limitations and conditions which apply to other rear extensions allowed under permitted development. These are set out in Class A, and include for example, the requirement that the extension (apart from a conservatory) must be constructed using materials of a similar appearance to those used in the construction of the rest of the house.

10. To benefit from these permitted development rights, the extension must be completed on or before 30 May 2016. The developer must notify the local authority in writing of the date of completion.

*See paragraph A.1(ea) of Class A, Part 1, Schedule 2 of the Town and Country Planning (General Permitted Development) Order 1995, as inserted by the Town and Country Planning (General Permitted Development) (Amendment) (England) Order 2013, available at

** See paragraph A.4 of Class A, Part 1, Schedule 2 of the Town and Country Planning (General Permitted Development) Order 1995, as inserted by the Town and Country Planning (General Permitted Development) (Amendment) (England) Order 2013, available at


The raising and sealing of a manhole cover inside a building will no longer be acceptable on a public sewer. On public sewers the only option is to reposition the manhole cover outside the extension. This may not always be possible and will require a site visit from a surveyor or builder to carry out a survey. On private sewers (these are generally sewers that have no waste from other properties flowing through them) it will still be okay to raise and seal an inspection cover. For further information please view information films at

If the diameter of the drain is over 225mm a build over agreement will not be permitted.

Under no circumstances can you build a mains water supply.

If Build Over Agreement is done through Test Valley Borough Council Building Control, they may require a CCTV inspection and report before and after which will cost around an additional ?240. Again this would be paid directly to the surveyor by the client.

What are the implications of not having a Build Over Agreement when building over or within 3m of the main drain?

Householders and developers planning to build close to or over a public sewer have to seek permission from the relevant sewerage company. Building close to or over a public sewer without having obtained formal approval is illegal. It may also jeopardise the future sale of your property.

The new extension may have to be demolished if the sewage drain is or becomes damaged, at the householder’s expense.



The introduction of the new Part L has caused Building Control Bodies and industry difficulties in deciding what constitutes a conservatory to be exempt from making a Building Regulations application. The definition of a conservatory previously contained in AD L1B of the April 2006 edition is no longer included in the 2010 Approved Document.

This best practice note is intended to provide guidance that will promote a consistent approach to defining what a conservatory is, for the purposes of being considered exempt from the need to make a Building Regulations application.

What is a conservatory?

To establish whether the conservatory extension is mainly exempt, we must look to Class 7 of Schedule 2 to the Building Regulations 2010. This tells us that to be exempt it must:

  • be at ground level
  • not exceed the 30m2 floor area
  • be thermally separated from the building it is attached to
  • have an independent heating system from the main building
  • have glazing meeting Part N in critical zones.

The question now arises as to what constitutes a conservatory as opposed to any other type of extension.

In the absence of a specific definition in the Building Regulations of a conservatory, reference can be made to dictionary definitions which give a variety of options as to the description and purpose of a conservatory.

A common factor in many descriptions is of a glazed structure often used for growing plants, and sometimes reference is made to it being an extension, but there is no indication as to the amount of glazing that should exist for the structure to be considered as a conservatory. It must also be borne in mind that at no point do the regulations stipulate what the space should be used for, albeit various uses are suggested in dictionary descriptions.

In the vast majority of situations, these structures are built as a form of a living extension to homes, with in many instances ancillary heating provided for those times when it is occupied.

In the interest of national consistency of interpretation, the guidance on levels of glazing contained in the superseded Approved Document L1B 2006 still gives a valid basis for a decision. In other words an ?exempt conservatory? should:

  • have at least 50% of external wall area formed from translucent materials (not including walls within 1 metre of boundary*)
  • have at least 75% of roof area formed from translucent materials
  • be at ground level
  • be effectively thermally separated** from the main part of the dwelling.

But after establishing a fit with the exempt criteria of Schedule 2 class 7 it must be remembered that Regulation 9 still enables control under Requirement P1 (electrical safety), G1 (cold water supply) and G3(2) and (3) (hot water systems) if they are applicable.

Approved Document L1B

The exemption status for conservatories is slightly complicated by Paragraph 3.16 of Approved Document L1B which removes exemption if the heating system of the dwelling is extended into the conservatory.

The removal of such exemption should only apply control about requirement L1? Conservation of fuel and power. In this way, an owner would be required to submit a Building Regulation application, but control would be restricted to demonstrating compliance with Part L only.

In such cases, the extent of control will depend on whether the conservatory’s heating system has independent temperature and on/off controls***. If it has, there is no limit on the area of glazing, but all glazed and solid elements should meet the thermal performance specified in Tables 1 and 2 to L1B, and the heating system should comply with the Domestic Services Compliance Guide 2010.

If independent control is not provided, then the limits of the glazed area in L1B section 4 apply in addition to the above.


Legislation and guidance on this subject leave room for interpretation, hence a potential for variance in application between local authorities around the country can arise.

Adoption of this guidance will serve to promote a consistent approach when dealing with conservatories, this being in our interests and most importantly those of our customers.

Definition of conservatory

It is proposed the use to which a conservatory is put is the choice of the occupier, with the proviso that should any fitting or controlled service be installed the definition may well change.

Permitted areas of glazing

The permitted area of glazing to roofs and external walls is as described above.


  • There is a potential for excessive unprotected areas where external walls are in a boundary situation. Consideration for fire safety as opposed to the need to meet a specified level of glazing should form part of the assessment in relation to the permitted area of glazing in the external walls of a conservatory. It is considered that where external walls to conservatories are within 1 metre of an adjacent boundary it is more important to achieve reasonable fire separation than to insist upon a minimum level of glazing in such a wall simply to assist achieving exemption status.
  • Effective thermal separation means that walls, doors and windows between the dwelling and the extension are insulated and draft proofed to at least the same extent as the existing dwelling?s external elements.
  • Independent temperature and on off control could typically be achieved using thermostatic radiator valves within the conservatory.

Document by the Local Authority Building Control in England and Whales.