This post discusses Building Regulations surrounding garage conversions and how to best comply with them.

Here at the Technical Centre we talk to a lot of people who are converting existing garages into a habitable space.  Moving into a bigger house or climbing the property ladder may prove costly for some at a difficult time economically, so the idea of making better use of their existing space is favourable.  This makes sense when a lot of garages are typically used to store all sorts of ‘stuff’ and not always the car.

Most modern cars are too big for older garages, as well as being rust resistant, which means the garage space can happily undergo a transformation. When designed effectively this can create an extra habitable space.  The new design could be in the form of a utility room freeing up kitchen space.  A downstairs shower room or toilet can be added. Often an upstairs office is moved downstairs freeing up a bedroom or the space can be used to extend the general living area. Whatever the use, the aim of the converted garage will be to ensure the finished look blends with rest of the house and is built safely conforming to building regulations.

What are Building Regulations and why are they so important?

The building regulations are minimum standards for design, construction and alterations to virtually every building including the change of use of a garage into a habitable space.  They are developed by the government and approved by Parliament.

They are important because they also contain a list of requirements (referred to as Schedule 1) that are designed to ensure minimum standards for health, safety, welfare, convenience, energy efficiency, sustainability and to prevent misuse, abuse or contamination of water supplies.

These regulations set national standards for building work and cover all aspects of construction, including foundations, damp-proofing, the overall stability of the building, insulation, ventilation, heating, fire protection and means of escape in case of fire. They also ensure that adequate facilities for people with disabilities are provided in certain types of building.

The local authority in the form of a building control officer will periodically visit the site and check building work to ensure it complies with building regulations.

Getting permission and Building Regulations

Usually you won’t need planning permission for a garage conversion but there are exceptions, for example when you live in a listed building or if the project increases the size of the building when it may be considered an extension.  It’s always best to check with the planning department of your local council whether planning permission is required before doing anything.

On the other hand, a garage conversion will always have to comply with Building Regulations and a building plan is usually submitted to the local authority for approval.

How to comply with Part L1B of the Building Regulations?

As part of the building plan, garage conversions need to demonstrate compliance with Part L1B of the Building Regulations which is specific to the conservation of energy in existing domestic homes. The document offers practical guidance on how to comply with energy efficiency requirements; this will help to ensure the newly heated habitable space doesn’t lose too much heat and so feels warm and comfortable.

The guidance defines a garage conversion as retained thermal elements. A thermal element is classified as a roof, wall or floor.  The guidance goes on to provide target U values for the retained thermal elements.

A U-value measures the heat loss through a typical square metre of a roof, wall or floor. All materials used in building each element, (apart from thin membranes like polythene,) contribute towards its thermal efficiency. How much it contributes depends on the materials thickness and its thermal performance.

In a typical garage conversion everything that is technically, functionally, and economically possible should be done to achieve the target U values described in Approved Document L. The walls should achieve 0.30W/m2K, the roof should achieve 0.18W/m2K, and the floor should achieve 0.25W/m2K.

Still to come…

Read Part 2 of the garage conversion series here, which discusses how to insulate your garage to meet the required energy efficiency standard or U-value, and secondly to ensure it is done correctly so as to minimise the risk of harmful interstitial condensation.