Saffron Design and Build Windows and Doors Ltd

Few people actually seem to keep their car in the garage, so planning a garage conversion to create another habitable room can be a good way of enhancing the value of your home. It is also far more cost effective than building a new extension and less prone to planning complications.

Before you start, consider what you’ll do with everything currently kept in the garage. If you store a lot of garden gear in it, you may need to factor a shed into your plans; if it’s where you keep your chest freezer, you’ll need to work out where it can be moved to — or whether you can live without it. If you really have no room anywhere else for these things, perhaps a partial garage conversion (or a conversion that has lots of storage space set aside within it) will work better for you.

A basic garage conversion will cost around £1,000 to £1,250 per square metre – if the walls and floor are stable, there is a watertight roof, and the ceiling height is sufficient to leave around 2.2-2.4m of headroom after building up the floor by 15cm above external ground level.

If the structure is attached to the house, rather than integral, and needs structural repairs, it may be more cost-effective to demolish and replace it.

Design costs

Design fees for a garage conversion range from £1,200 to £2,500, plus £300 to £400 for a structural engineer. A typical single garage conversion (18 square metres) would cost around £17,100 to £23,900, and a double (36 square metres) £31,300 to £43,300, plus VAT, depending on personal specifications.A basic garage conversion will cost around £1,000 to £1,250 per square metre – if the walls and floor are stable, there is a watertight roof, and the ceiling height is sufficient to leave around 2.2-2.4m of headroom after building up the floor by 15cm above external ground level.

If the structure is attached to the house, rather than integral, and needs structural repairs, it may be more cost-effective to demolish and replace it.

Design costs

Design fees for a garage conversion range from £1,200 to £2,500, plus £300 to £400 for a structural engineer. A typical single garage conversion (18 square metres) would cost around £17,100 to £23,900, and a double (36 square metres) £31,300 to £43,300, plus VAT, depending on personal specifications.Typically, a garage conversion will cost more if the original structure is unsound. If you are going to spend a lot of money stabilising the building, knocking the original garage down and building from scratch might be cheaper.

Another factor to consider when costing a garage conversion is the perceived value that it will add to your home. Check the value of houses in your area, if there is little off-road parking, homes with garages might be valued higher than those without. Unless the added space is vital, don’t run the risk of reducing the value of your own home.

A partial garage conversion should cost less, but not by much. Fewer materials will be needed, but services, such as electrics and plumbing, will still have to be installed and budgeted for.

In the majority of cases, the work involved in converting a garage will be classed as permitted development. However, if you live in a Conservation Area, a location where development can be restricted to protect the appearance of the surroundings, or on a new estate with strict guidelines, it’s worth checking what’s allowed.


If in doubt, apply for a certificate of lawful development from your local authority at a cost of £86. Do remember, the removal of permitted development does not rule out the potential of a garage conversion, but you’ll need to ensure the design is sensitive to the setting and apply for full planning permission, which costs £172 in England. Listed properties will need listed building consent, too.

When you will need planning permission:

If you live in a listed building;
If the garage conversion increases your home beyond permitted development rights;
You are converting the space for business;
Your council has restrictions on reducing parking.
Even if these restrictions apply, you should be able to convert the garage interior as long as the exterior is untouched.

DON’T FORGET BUILDING REGULATIONS APPROVAL
You’ll need building regulations consent and sign off for the various elements of your garage conversion, as with other home alterations. Always check that your local council is happy with your plans before starting work. For details, see planningportal.gov.uk.

As a ‘change of use’, a conversion is always subject to building regulations approval, so your local authority will need to be notified. You can use the council’s building control service or an approved independent inspector, costing around £300. To comply, the garage has to be structurally sound and have a damp-proof course; the walls, floor and roof will need to be upgraded for energy efficiency, and all new and existing electricals will need to be tested to ensure safety, including in the house.

Other permissions

Sometimes there are legal restrictions on alterations to a property, so check the deeds to your home to see if permission is required from a previous owner. If the work affects a structure shared with an adjoining property, the Party Wall act will also apply.