Extending your home is becoming an increasingly popular choice with homeowners who are looking for more space, experiencing a change of circumstance or even just wanting to ‘spruce up’ a tired property.

Home extensions can take many forms and can be used for any purpose that the client wishes, from a simple porch extension or conservatory to a complex multi-storey extension used for a garage, utility, kitchen, living & dining room.

Thinking of extending your home?

Having an extension built on your house can be one of the most exciting projects you may ever take on. Once you’ve taken the plunge, had plans drawn up and planning permission has been given, there is the daunting task of finding a builder.

Don’t be put off by all the publicity about cowboy builders. It wouldn’t be news if all builders were the same. The large majority of builders are reputable and will do a good job on your building work.

Porches

Porches are typically small extensions to the front of a house, although they can be much larger and can be built to the side or to the rear. They are generally simple structures of only brick dwarf walls and columns, windows and a door. They can be plastered or left as bare brick and generally have a light and possibly an electric socket.

Most porches do not require planning permission due to their size, although some do, and it is best to check, see  the Is Planning Permission Needed? page. As long as the porch is separated from the house by an internal door, and it is not heated, then it will not require building regulations certification. If you have electrics in it however, you must either use a Part P registered electrician or have the job inspected by the building control department and pay their fee. See the Building Regulations section.

Typical costs can start at around £2,500*

Conservatories

Fairly simple structures are usually made of UPVC, although they can be timber or aluminium. Some conservatories require planning permission and some do not. See Is Planning Permission Needed? The rules on building control apply as to porches (above).

Typical costs can start at around £4,000*

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Orangeries

An orangery, or sunroom, is essentially a conservatory with a solid roof and walls – albeit with plenty of glazing as well. They have the advantage of being sturdy and warm, while also bringing in a lot of sunlight. Typically more expensive than a conservatory, it is advisable to employ both an architectural company and a building company experienced in this type of project.

Rules for orangeries are very similar to that of conservatories for Planning Permission. Building control permission will almost certainly be required.

Typical costs can start at around £12,000*

Single storey extension

Single storey extensions are simply an extension built onto a part of the house whereby one side (or more) of the extension adjoins the property and there is only the ground floor plus any basement built to it.

Main considerations here must be the size of the extension and its impact upon neighbours, how the roof will work with the existing building and specifically whether the same type of roof covering of the existing property can be used on the extension. Positions of flues, drains and excavations must all be considered.

In some instances planning permission will not be required for single storey extensions. Building control permission will almost certainly be required.

Typical costs can start at around £8-10,000*

Two storey or multi-storey extension

A multi-storey extension can, like a single storey extension, also be built to any part of the existing building. However, with an extension of more than one storey, the possibility of nuisance towards neighbours is much stronger. In some instances it may be possible to build what you want without requiring planning permission, but we would strongly advise that you get a letter from the Planning Department to cover this.

Typical costs can start at around £25,000*

Over-structure extension (typically over-garage)

An over-structure extension is, as it sounds, where you are extending over the top of an existing structure such as a garage, a kitchen, a living or dining room.

Unfortunately this is not as simple as many people think.

For example, many houses have only single-skin brickwork for garages. This is not sufficient to build up-over as the new brick and block work above is twin-leaf. The solution is either to dig down through the garage floor, install a new foundation and a new inner leaf, or to install blockwork ‘piers’ in the garage and fix a steel beam over the top of these.

Similarly, there is a potential problem if you are building over the top of a kitchen or dining room which has a twin leaf wall but was built in the 60’s. Because the conditions of the foundations cannot be guaranteed, it is generally necessary to dig a trial hole to investigate.

In terms of planning permission and building control, the rules about whether or not you need planning permission are far more difficult to define in these instances and depend on distances to boundaries, between neighbours as well as aspect ratios and other factors, and you are well advised to seek specialist advice. Building control permission will almost certainly be required.

Typical costs can start at around £22,000*

Loft conversions, basement conversions, & garage conversions

These are all types of home extensions also, see the Lofts & Basements and Garage Conversions sections for more details.

*Figures are rough estimates and may not be representative for the whole of the country. 

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