Buying to extend: the legal issues

Purchasing a smaller property with the potential for an extension

When a family wants to upgrade to a larger family home or an individual wants to get on the property ladder, they will often consider buying a smaller home with a view to building an extension following the completion of the purchase. Many properties will have the potential for an extension to be added or existing features such as an attic or a basement being converted into extra living space (eg, a bedroom).

Purchasing property in this manner will enable the purchaser to save a considerable amount of money and allow them to be in control of the design and the quality of the building work.

Permitted development

Some extensions will be considered permitted development under The Town and Country Planning (General Permitted Development) (England) Order 2015 and will not require planning permission, but this will depend on the area you live in and the type of extension you want and it is always advisable to check with your local planning authority if planning permission is required before you buy to extend and embark on any building project.

No planning permission will usually be required as long as:

  • no more than half the area of land around the original house is covered by the extension or other buildings;
  • the extension isn’t at the front of the house or facing a highway;
  • the extension isn’t higher than the highest part of the roof;
  • a single-storey rear extension doesn’t extend beyond the rear wall of the original house by more than 3m (attached house) or by 4m (detached house). Until 30 May 2019, these limits are increased to 6m (attached house) and 8m (detached house) but this will require you to notify the local planning authority of your plans and successfully go through a neighbour consultation scheme before you can go ahead;
  • a single-storey rear extension is less than 4m high;
  • two-storey extensions are no closer than 7m to the rear boundary
  • two-story extensions don’t extend beyond the rear wall of the original house by more than 3m;
  • materials used for the extension and roof pitch of extensions higher than one storey are similar to the existing house;
  • there aren’t any verandas, balconies or raised platforms;
  • maximum eaves heights are complied with;
  • upper-floor, side-facing windows are obscure-glazed and any opening to be 1.7m above the floor.

Stricter rules apply if your property falls within designated land (ie, conservation areas, national parks and the Broads, Areas of Outstanding Natural Beauty, and World Heritage Sites) and Sites of Special Scientific Interest.

Planning issues

The planning department of the local council for the area in which the property is situated will be able to provide pre-application advice before an application for planning permission is submitted.

This pre-application advice is given by the planning department ‘without prejudice’, meaning you won’t have any legal come-back if a formal planning application is made and rejected.

A duty planning officer will be consulted when the formal planning application is being made. They will give guidance on all procedural aspects of the preparation and filing of the planning application.

The final decision on whether or not to grant planning permission will lie with the planning committee. The duty planning officer can make recommendations but ultimately it is up to the planning committee as to whether these recommendations are taken into account in the final decision.

Planning permission options

There are two alternatives available to someone wishing to purchase a house with a view to extending the property. They are:

  • immediate application for planning permission;
  • offer subject to planning permission being granted.

Immediate application for planning permission

An individual wishing to purchase a property with a view to extending it may be able to make an application for planning permission as soon as the offer for the property has been accepted. If the seller does not wish to sell immediately it may be possible to delay the exchange and completion process. However, this may be difficult if the sale of the property is part of the chain.
It may also be difficult to get the required information and opinions to make the planning application as soon as the sale goes through as much of this will need to be done prior to exchange and completion.

Offer subject to planning permission being granted

It may be possible to make an offer for the purchase of the property dependant on the planning permission being granted. This offers a no risk solution as the purchase of the property will only go ahead once the planning permission has been granted. Accordingly, it is a common solution used when land is being sold to developers.

It is legal for this to be done as the offer will have to be agreed upon by both parties in the sale of the property. An appropriate term will have to be inserted into the contract for the sale of the property.

If planning permission is not granted, the sale of the property will not go through and any deposit which was paid on the completion of the contract will be refunded.

This will only be able to done when both parties to the sale of the property can adhere to the time delay between the offer being accepted and the planning permission being granted.

Accordingly, it may be difficult for the purchase of domestic property when the property is involved in chain where a quick sale may be required. This may, therefore, be a more attractive option for commercial property deals whereby land is sold for development.

Article written by...
Nicola Laver LLB
Nicola Laver LLB

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A non-practising solicitor, Nicola is also a fully qualified journalist. For the past 20 years, she has worked as a legal journalist, editor and author.