The average garage conversion cost is £10,500 for a single garage and £16,000 for a double garage. The total cost depends on the type of garage you are converting, its age, existing condition and of course its size. A new build integral garage will be below the average price while an old delipidated detached garage will be above the average price.

The table below shows the cost of basic room conversion for a standard sized single and double garages. We've measured hundred of garages and have an average of 13m2 for single garages and 26m2 for doubles.

The type of garage is also a major factor in the overall cost, the 3 types of garages are:

  • Integral - Part of the footprint of the house with a room above
  • Attached - The walls join to the main house and the garage has it's own flat or pitched roof
  • Detached - The garage is separated from the main house

How Much Does a Garage Conversion Cost?

Garage Type

Single up to 13m2

Double up to 26m2

Integral Garage



Attached Garage



Detached Garage



Partial Integral

£6,000 (8 m2)

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If you have an odd size garage and want an idea of the cost you can divide our estimates by the number of meters to get the cost per m2. Then multiply this with your own floor area measurement, or better yet use the button below to get a free quote. 

Garage Conversions: Prices Breakdown 

Read on to learn where your money goes, what work is involved and why the price differs. 

Integral Garages Conversion

Normally the cheapest type of garage conversion and most of the cost is related to replacing the garage door with a new wall and window. Depending on the insulation levels you may also need to upgrade the existing walls to meet building regulations. If the new space is a basic room such as a bedroom or dining room the price can be surprisingly affordable. Basic rooms don't need any plumbing and drainage work. Hence, you will find this is one of the most cost effective ways of adding more living space to your home.

Attached Garage Conversion

These are slightly more expensive than integral garages as extra insulation is required to the roof. Single skin garages will also increase the cost as a new internal leaf (timber stud wall) will be required. This is also an opportunity for you to upgrade the energy efficiency of your homes thermal envelope and you should ask your designer about the possibilities of additional insulation above what the building regulations specify as a minimum. If the garage has a flat roof, it may be worth replacing this entirely which will add around £2000 to the cost. This is another great opportunity to improve the energy efficiency with extra insulation as more heat is lost (per square metre) through the roof  than other building elements. 

Detached Garage Conversion

With all four walls requiring thermal upgrades this is normally the most expensive garage conversion. Projects such as granny flat conversions which require plumbing, bathrooms, kitchens and multiple windows will always be at the top end. However, per square meter it is also the best value for money garage conversion when you consider how much value the new living space adds to your property. Its even possible to turn your garage into a separate home with the right team and planning permission. 

If the extra space is for a home gym, office or hobby room then the costs will be considerably cheaper. Depending on the project type and your garage’s location a loophole in the building regulations could allow you to make significant savings. Contact us with details of your project to find out if this is possible.  

interior of double garage conversion

Partial Garage Conversion

Depending on the existing structure that is going to be part converted this can be the most cost effective and beneficial home improvement you can make. Half garage conversions can provides substantial improvement to the layout and overall usability of your home. Having a utility room and downstairs toilet can also add value to your home and free up valuable space in the kitchen. Dividing the garage with a stud wall while retaining the garage door and some storage space means you avoid a large proportion of the costs whilst also having some room for bikes, lawnmowers etc.  

Double Garage Conversions

You will be pleased to know a double garage conversion cost isn't necessarily double the price. Although they offer twice the floor space the perimeter is only around 30% larger. Therefore the amount of wall space to insulate is not that much more than a single. If you are lucky enough to have an attached double garage there are even less walls to insulate due to at least one of them being internal. Making the project an economical way of adding large amounts of extra living space to your home and far cheaper than for example a loft conversion which adds a similar amount of usable space

Garage Conversion ready for decoration

Breakdown of costs for an average room conversion to a standard size garage

The table above is for the building work cost including labour charges and materials. Below is a breakdown of where that money will be spent:

  • Infill wall built on new foundations.
  • New Upvc Window
  • Insulation and plaster board to all walls and ceilings.
  • Plastering skim coat.
  • Joinery work including door, skirting boards, architrave and window sill.
  • Extending the electrical system to add lights and sockets.
  • Extending the heating system or adding electric radiators.

Heating system costs 

We have produced a full article on the best way to heat your extra living space which depends on the type of garage and location of existing system. For detached garage conversions it is almost always most convenient to use an air conditioning system which are well suited to standalone installation. 

Underfloor heating is an energy efficient way of heating your new room especially if its a double garage. The pipework systems cost from only £325 but expect to pay at least the same in installation fees which vary depending on how easy it is to reach the heating systems manifold. 

Prices Vary By Location

The cost table above is based on work in the North East Region. Labour costs will make up a large part of the total price. Therefore due to regional labour rate differences your quote may vary. The following table is a guide on the percentage variance by regions and was assembled using average construction wages reported by the construction index.


Percentage Difference

North West

additional 9%

Yorkshire & The Humber

additional 10%

East Midlands

additional 12%

West Midlands

additional 11%


additional 9%

East of England

additional 15%


Additional 13-20%

South East

Additional 12%

South West

Additional 9%

Additional costs to consider.

Unfortunately, before we can break out the power tools there are some administrative tasks and architectural design works to confirm. 

Admin, Legal and Architectural Costs

Most garage conversions fall under permitted development. However, some projects will require planning permission, building regs and the removal of restrictive covenants which all add to the total cost of your garage conversion. The table below provides a breakdown and estimate of these fees. 


Drawings & Professional Fees

Statutory Fees 

Planning Permission Cost



Building Regulations Cost



Restrictive Covenant Cost



Do i need to pay both?

To get the total building regulations fees you will need to add your professional fees and statutory fees charged by your local authority/private company.  

 Most projects won’t need all the services listed in table and if you do the price for drawings will be less than simply adding the amounts together. The reason for this is the planning drawings can be used to discharge restrictive covenants and then also developed to include building regulations once the planning permission is granted. If you are unsure what your project requires get in touch here for some free advice.

Architects Cost

As shown in the table above the cost will range from £400-1200 depending on the demands of your project. Not all garage conversions will need an architect involved and if you do need architectural drawings, it may be cheaper to use a technician or draughtsman. Some builders and specialist companies (like us – shameless plug 😉) have in house staff that can provide architectural services as part of the package.

That being said, if you are planning a large garage conversion which also involves reconfiguring the layout of the ground floor then an architect and the design ideas they bring to the table may be priceless. If your garage conversion design includes an open floor plan with large new openings you may also need a structural engineer. The engineer will calculate the sizes of steel beams and provide a spec for approval by the building control office signing off your project. Don't be tempted to try and save money by skipping this step. Also the right builder will insist on having proper specifications for the new beams. 

Finished Surfaces

After the building work is complete, finished surfaces can be installed adding the wow factor to the new room. The price of finished surfaces will vary depending on your own personal preferences, but the table below is a useful starting point.

If you are competent at general DIY then the finishing jobs could present a great opportunity to get your hands dirty and save a few £££ in the process. But remember this is the part of the job you will see every day and no one wants a squeaky floor that serves as a constant reminder you forgot to add an expansion tolerance. So unless you are confident in your abilities getting the pros involved could be the right choice. 

Flooring Choices

The table below is an estimate of supply and fit for the basic spec of each material including underlay. We would recommend that you invest suitably in materials like tiles where the labour cost makes sense to match with a quality product that will stand the test of time. Expect to pay around £35 per meter for a tiler with some tilers including the adhesives and grout. 

Flooring type

Single Garage 13m2

Double Garage 26m2

Laminate @ £25 per m2



LVT Click Flooring @ £38per m2



Tiles @ £70 per m2



Carpet @ £20 per m2



Garage Conversion with karndean floor

Internal Doors

An essential part of converting your garage is fitting an internal door to the new living space. The new door itself can be purchase for less than £30 but of course you will want to match this to the existing doors which may dictate the price. The same design of internal door may also be available in different quality materials such as solid wood which is more expensive than the inferior hollow core doors. Some conversions may require an FD30 fire door, if this is the case expect to pay £100 upwards for this type of door.

Double doors often cost a lot more than the price of two single doors. This is because they are made in smaller quantities and as a pair which includes a rebate for the doors interlock. A cheaper option is to buy something called a pair maker to turn two standard single doors into a double. Speak with your joinery team about this budget friendly option.  


A professional decorator is the last man on the job and often left to catch small imperfections, I would always recommend getting your decorator to inspect the builders work prior to payment for the main build otherwise the original quote may increase due to additional prep work. A single garage should cost from £500 and a double garage around £900 with general emulsion and gloss paint included. If you want the on latest on trend Farrow and Ball colour, then this would increase the cost respectively.

Tips to save money on your garage conversion

  1. Don't skip your old garage door, especially electric garage doors they can be worth a few hundred pounds and are easily sold on gumtree or Facebook. 
  2. Get your hands dirty with a bit of DIY, tasks such as emptying the garage are a sure way to save some money and help the builders see what they are working with. You could also dig the foundations for the new wall if you're up to it. 
  3. Think ahead about the design and placement of any fixtures especially plumbing and electrics. Making changes to the design once the work has started can be very costly. 
  4. Retain the original concrete floor. It may be suggested that the original garage floor does not meet regulations and should be dug up and replaced with a layer of insulation and finished with new concrete. A cheaper way is to retain the floor without insulating or build a floating floor with some insulation (if the floor height allows). While this may not upgrade the floor performance to the specified U-Value levels, building control should approve of this method. You can increase the performance of your building envelope by adding additional insulation to other areas. The walls or ceiling are a great place as they are more convenient and cost effective. Not only is this method better for your budget but it also reduces the carbon footprint of the project and saves the original concrete floor going in the skip. 

Summary and average cost of garage conversion.

By now you should have a good idea of the costs involved in converting your garage. The base price of single garage conversion is around £10,000 and could increase the value of your home by the same amount if not more. This makes converting your garage one of the best home improvements you can make. So why wait? join our many happy customers and take the first step by requesting a free quote today. As part of the service we can talk you thought and clarify any questions about planning permission and building regulations to give an accurate total quotation.  

About the Author Michael NEGC

Michael is the Architectural Designer and Surveyor at North East Garage Conversions.
Michael has a HNC in Civil Engineering and a HND in Construction Management. Previous experience includes multiple renovations, a self build plus working as an Architectural Technician, Designer and Project Manager.

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