If you really do love your home and it’s in just the right location, you’ll be loath to move away. But you need more space. The family is growing and you yearn for more room to entertain, or even to work from home. The solution? A home extension or a loft conversion.

The conversion of a property may add to its value and increase its rental yield. The type of property conversion you decide on will depend on your budget and the permission granted for conversion work by your Local Planning Authority (LPA).It is important to choose the right property to convert,the right type of conversion

and, to ensure the work is compliant with building regulations and planning rules.

Property conversions can usually be described by one or both of the following terms:

  • Splitting: This takes an existing building and splits it into smaller units, e.g. from a large house into smaller apartments, or from a one to a two bedroom property
  • Change of use: Conversion of a property from one use to another, e.g. from a pub to flats

Understand the local housing needs

Conducting thorough market research to identify trends and gauge local demand will highlight the type of conversion that will be best suited to a given area. If the research indicates that more young families are moving to the area, for example, then adding an extra room to a one bedroom house could be a viable option.

Planning permission

Planning permission is required for most major changes to existing buildings, including extensions, conversions and change of use. In some situations, additional permissions may be necessary, such as if the building is listed, or the property is in a conservation area.Although certain common building projects fall under ‘permitted development rights’ and do not require planning permission, building regulations will apply to most building work. It is therefore recommended that conversion proposals are discussed with your Local Planning Authority and Building Control Service (BCS) prior to instructing an architect.In some circumstances it may not be absolutely clear if planning permission is required or the work is classed as a permitted development. While not compulsory, obtaining a Lawful Development Certificate (LDC) can be useful if you ever need supporting documentation to prove that the building work is lawful.

Splitting units

Splitting larger properties into smaller flats or apartments can be a costly process, but if the conversion is well-managed and meets the area’s demands, it can increase return on investment.The process may require the services of an architect, and the following factors should be given consideration:

  • Council tax: Buildings with common areas ordinarily attract a single rate of council tax, but separate, self-contained units may vary
  • Utility meters: Utility meters must be installed for each flat or apartment, and must comply with government approved standards
  • Energy performance: An Energy Performance Certificate (EPC) must be provided for all buildings, detailing the energy efficiency of the building
  • Fire safety: Converted flats and buildings with common areas must adhere to government regulations, e.g. smoke alarms must be placed at every level of the building and regularly tested
  • Sound insulation: Under Building Regulations 2010, every building must be insulated to protect against noise and reverberation from other parts of the building and adjoining buildings
  • VAT: Renovation and conversion work on a property is subject to VAT, although a lower rate is payable on buildings that qualify under the 2001 Urban Regeneration Scheme. More information on this can be found in VAT Notice 708
  • Insurance: Public liability cover may be required when conversion work is undertaken, and buildings insurance will be required throughout ownership of the property
  • Tenure: Permission will need to be granted by the freeholder, and if you are the freeholder you will need to decide whether the new units will pay a ground rent on a leasehold basis, or whether the freehold will be shared

Change of use

The Town and Country Planning (Use Classes) Order 1987 groups the various uses of buildings and land into categories known as ‘Use Classes’. When the present and proposed uses fall into the same class or there is a ‘permitted change and planning permission may not be required.Nonetheless, it is important to discuss any proposals with the relevant Local Planning Authority and Building Control Service before starting any work to avoid what could be expensive and time-consuming remedial action, such as restoration or even demolition.If you convert a property into a house in multiple occupation (HMO) – a property three or more stories high and housing five or more people from two or more families – the landlord or building manager will be required to obtain a specific licence.

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.
  • In addition, outside Article 2(3) 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 2019.
  • These increased limits (between 3m and 6m and between 4m and 8m respectively) are subject to the prior notification of the proposal to the Local Planning Authority and the implementation of a neighbour consultation scheme. If objections are received, the proposal might not be allowed.
  • 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 single storey with maximum height of four metres and width no more than half that of the original house.
  • Two-storey extensions 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 conservation areas, national parks and the Broads, Areas of Outstanding Natural Beauty, and World Heritage Sites.

Please note: The permitted development allowances described here apply to houses and not to:

Installation, alteration or replacement of a chimney, flue or soil and vent pipe: Read guidance on the permitted development regime under Class G of the regime.Please be aware that if your development is over 100 square metres, it may be liable for a charge under the Community Infrastructure Levy.

Permitted Development for householders – Technical Guidance

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.View ‘Permitted development for householders – Technical guidance’ on