Garage conversion: Where do I start?

Garage conversions continue to be an appealing option for homeowners. Not only are they an easy and cost-effective way to create liveable space, but they can also add up to 20% to the value of your home. Here's what to consider including costs, design and

Angela Kerr Director, Editor

Should I convert my garage?

Almost half of us use our garage to store junk rather than cars. Research by RAC Home Insurance found that four in 10 of us can’t fit our cars in the garage anymore due to the amount of clutter.

If your garage is wasted space where you simply pile up junk, then converting it into a useful room could improve the way you use your house as well as add value. Virgin Money estimates that converting your garage into an ensuite bedroom could add 20% to the value of your home.

Given that the average garage conversion costs around £6,000 it is a cost-effective way of increasing your living space.

How much does a garage conversion cost?

A garage conversion is a relatively low-cost way of increasing your living space. That’s because, unlike an extension, you don’t need to pay for laying new foundations or building new walls. And, your garage may also already have power.

Several builders and architects we spoke to put the cost of converting the average garage into a liveable room at between £5,000 and £7,000. This cost could increase though if there are structural changes, plumbing needed or utilities to be added.

Other factors that could affect the cost of your garage conversion

The other factors that can affect the cost of your garage conversion include:

• Whether the foundations need to be reinforced.
• If the walls, floors or roof need to be repaired. It may be cheaper to demolish your garage and start again if it is in a particularly bad state of repair.
• If the ceiling height needs to be raised – you need around 2.2-2.4m of headroom once the floor is 15cm above the external ground level.
• If you use an architect or designer.
• Planning applications.
• Whether you need to use a structural engineer.

Do I need planning permission to convert my garage?

Most garage conversions can be completed under permitted development rights, particularly if you aren’t planning to alter the structure of the building. But you should check that there are no planning conditions attached to the garage – for example that it has to remain as parking. You can do this by checking the deeds of the property.

If you are converting a detached garage, then you may have to apply for a change of use.

Here at the Homeowners Alliance we recommend that you check with your local planning authority to make sure your garage conversion falls within permitted development.

If your home is listed or you live in a conservation area, then it is highly likely that you will need planning permission before you can convert your garage. In this scenario, we would recommend having an informal meeting with your local planning officer before you submit your application.

Find out more with our guide to planning permission.

Building regulations for garage conversions

A garage conversion classes as a ‘change of use’ so it will require building regulations approval.

To comply with building regulations your garage conversion must:

• Be structurally sound
• Have a damp-proof course
• Include wall, floor and loft insulation so it is energy efficient
• Have had all electrics safety tested
• Be moisture proofed, with good ventilation
• Have been fire-proofed and have escape routes

Because your project will need building regulations approval, you need to notify your local council before you begin work by submitting a building notice or full plans application – depending on whether you need planning permission or not.

Once the garage conversion is finished a building inspector will come to check windows, doors, fireproofing measures and foundations before issuing a certificate of completion.

Designing a garage conversion

You could choose to design your garage conversion yourself. But there are a number of other options. You could use an architect or architectural designer whose expertise mean they may come up with ideas you didn’t realise were possible.

Find a local architect or architectural technician to help you design your project:

Alternatively, a good builder should be able to plan and carry out a straightforward garage conversion. Or you could opt for a company that specialises in garage conversions. They will be experienced in dealing with the planning issues and building regulations specific to garage conversions. You can find a trusted local builder using our free Find a Builder service in partnership with the Federation of Master Builders.  Find trusted local builders that have been independently inspected to ensure their work is to a high standard and browse builder profiles to find those that have completed projects like yours.

Key works when converting a garage 

The main works involved when converting a garage include:

1. Making sure the walls and roof are sound.

2. Floor slab – the existing floor may need to be levelled, damp-proofed and insulated.

3. Infilling the door – Most garage conversions simply brick up the garage door.

4. Wall insulation.

5. Roof insulation.

6. Windows & doors.

7. Heating and electrics.

Insulating your garage conversion

It’s important that you make sure your new room is warm and energy efficient. In order to comply with building regulations, it will need insulation.

The simplest way to add insulation to the walls is with insulated plasterboard fitted to timber battens above the damp proof course.

Garage floors are usually lower than the floor in the main house so you should be able to add a damp-proof membrane, insulation and a new screed plus floor covering and end up level with the rest of the house. 

DIY garage conversion

It is possible to plan and convert your garage yourself. This could be a good option if you only have a small budget and are a pretty skilled DIY-er. Just be aware that your work will be checked by a buildings control officer and if it doesn’t comply with building regulations you will have to put it right at your own expense.

What insurance do I need during a garage conversion?

If you are using a builder they should have their own insurance to cover the building project. Make sure they have professional indemnity insurance before they start work.

You will also need to inform your home insurance provider before you start your garage conversion. Major building works can invalidate home insurance, so it pays to check. You may need to take out specialist additional insurance during the work if your home insurer won’t cover you.

Get a home insurance quote today from our partners at Howden Insurance

Once your conversion is complete get in touch with your home insurer again. The work may have increased the rebuild value of your home which means your premiums may rise.

Converting a detached garage

If your garage is detached it could be a bigger job than converting an integrated garage. For a start, you will have to apply for change of use with your local planning authority.

You will also need to factor in extra costs such as enhancing the foundations, which may not be strong enough for what you are planning. You may also have to consider costs such as bringing power and plumbing out to the building.

For further advice on whether you can modify your detached garage, you may wish to get the help of an architect.

Disadvantages of converting a garage

It is easy to see the advantages of converting your garage. You can add value to your home, gain valuable living space, and potentially lengthen the time you can spend in your current home. All for a relatively low price when compared with the cost of an extension.

But there are some disadvantages to a garage conversion too:

• Upheaval – while a garage conversion may be less intrusive than a loft conversion there is still likely to be noise, mess and general inconvenience when the building works are going on.
• Planning permission – if your garage conversion requires planning permission you may not get it.
• Building regulations – as the homeowner you are ultimately responsible for making sure the garage complies with building regulations. If works done do not comply, you may have to rectify the work at extra expense.
• Time, energy and money – as with any building project!

Want help getting your garage conversion right? Find a local architect to discuss your project.