Average garage conversion costs

Summary: How much does a garage conversion cost, average labour costs and average cost of materials.

Rather than moving house in order to gain more living space many people decide to convert an integral garage. There are many reasons for this. Some people want a home office as everyone has computers and ancillary equipment these days. Other people want a spare bedroom, whilst others may want their teenage daughter or son to have a space of their own.

Average Cost

Factors to consider

You probably will not need Planning Permission to convert a garage but you definitely will need Building Regulations. Contact your local authority who will help you through the process. There will be a few simple forms to fill in and a building inspector will come to view your garage and will give advice. There will be a charge for this service which can vary between local authorities. It should be less than £200.

If the proposed work involves enlarging the building, Planning Permission may be required. You will need to contact the Planning Department of your local council who will be pleased to help and advise you on how to proceed. Do not do any work without first consulting your local authority as they are well within their rights to ask you to reinstate the garage if the work has not had their approval or is not done to the correct standard.

If you live in a conservation area or on a new housing development it is possible that garage conversion rights will have been removed so you will need to check with your local authority. If yours is a listed building you will definitely need to discuss your proposals with the local planning authority.

If there is going to be a door to the house it will need to be a fire door. If the size of the garage is to be unchanged, the actual conversion will not involve a Change of Use and often requires no more than blocking up the existing front doorway and installing a window in its place. A window will need to have a trickle vent to allow some ventilation when the window is closed. Any infill needs to be supported by lintels or foundations as these are structural alterations requiring Building Regulation approval.

Suitable damp proof courses need to be incorporated in order to prevent any water seeping in through the new windows and also where infill joins existing walls. Some garages have cavity walling but in the case of single leaf walls, work will be required to improve weather resistance and thermal insulation. The Building Inspector will give advice regarding this which normally is achieved by building internal block walls. The existing floor will need to be checked to see if it can support any extra weight. If the walls will not take the weight it might be necessary to dig new foundations.

Internal stud walls need to be provided together with insulation. If insulation is to be put in the roof, the roof void needs to have ventilation. Modern membranes allow the walls to “breathe” as well as providing vapour barriers. The piers of the garage can also be insulated. There needs to be sufficient ventilation into the room and if a shower or WC is proposed, suitable drainage will have to be put in. Standards required will be found in the guidance notes with regard to Part L of Building Regulations.

If the work is to be undertaken by a builder he will need to provide written certification that the work has been done to the satisfaction of the Building Inspector. This is vital paperwork when it comes to selling your home. Without it, the room will be just considered to be a garage when it comes to the sale particulars and estate agents are well aware of this.

Costs to consider

A professional garage conversion can not only look good but can add much needed space as well as value to a home. It is simply a question of turning a basic shell of a garage into a room suitable for human habitation. Therefore the room needs to be warm, light, free from damp and well ventilated. Ideally, any window at the front where the door used to be should match in with the existing windows of the house to create a unified appearance.

A garage conversion is a straightforward job for a builder and one which will give immense pleasure to the home owner. A competent DIY’er might feel able to undertake the job too. This type of home enlargement is becoming the first choice of many people who have weighed up the costs of moving or improving.