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In 2013,  the government made it easier for owners to extend their homes as part of their permitted development rights without having to apply for planning permission in order to stimulate more building activity.

However,  homeowners need to act fast if they are to take advantage as all documentation has to be submitted to the local authority and relevant work must not just be started but completed by the end of May 2019. There’s no word yet on whether the  deadline will be extended – or on penalties payable if that date is missed.

An  increasing number of local authorities offer a useful consultancy service for a relatively small fee which will confirm whether a planning application is required which is particularly useful if owners sell the property within the first four years of completion.

Single storey extensions can measure  8 metres (26ft) in length for a detached house and 6 metres  (19.7 ft) for semi detached houses or terraces i.e. from the rear elevation of the original house as built or as it stood on 1 July 1948. Maximum height permitted is 4 metres  (13.1 ft) but, if the extension is within 2 metres (6.56 ft) of any boundary, maximum eaves height should be 3 metres (9.84 ft). Two storey extensions cannot extend more than 3 metres (9.84 ft)  and should be no closer than 7 metres (22.9 ft) from the rear boundary. Side extensions cannot be higher than 4 metres (13.1 ft) and not wider than half the width of the existing house.

No extension can project beyond or be added to what is deemed to be the front of the house or an elevation included which fronts on to the road. No more than half the area of land around the house (as on July 1st 1948) should be covered by building work. Materials must match the existing house with the exception of conservatories and the same roof pitch has to be applied as the main house.
Under permitted development rights, lofts can also be converted into bedrooms or extra living space by 50m3 in a detached house or by 40m3 within any other home.

Neighbours can make representations about the application within 21 days of notification by the Council of the proposal.  Whereas approval can take up to 42 days following ‘Neighbourhood Consultation.’ If complaints are made, then an appeal could take place. Otherwise  a formal planning application may be necessary. Either way, the extension will still have to comply with building regulations which ensure the work meets safety and energy efficiency standards.

Permitted development may not be possible for listed buildings, flats and maisonettes or in conservation areas. No verandas, balconies are allowed and special rules apply to chimneys, flues, soil and vent pipes. In some leasehold houses, permitted rights may have been withdrawn or cancelled.

It’s no surprise that improving not moving is proving even more popular bearing in mind  that extension nearly always works out considerably less expensive  than buying a larger replacement property.

Once the work is completed, the local council must be notified so that a  Lawful Development Certificate is issued which proves compliance with relevant rules. The documentation can be kept with the deeds for disclosure if the  property is sold or re-mortgaged.

More information is available on

Before taking the plunge, homeowners should ensure the cost is acceptable and unlikely to get out of hand! It would be a good idea to ask the advice of long-established chartered surveyor/  estate agents - like Jeremy Leaf & Co. They can also tell you without cost or obligation the likely impact of your proposal on the value and saleability of your home. It’s a good place to start!

Jeremy Leaf, a former RICS residential chairman &  independent North London Estate Agency owner.

Autumn 2018