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Garage conversion cost guide
by
Checkatrade

Why should I convert a garage?

Let’s face it, garages are usually one of the most poorly utilised spaces in a home. From being a place to store junk, piles of boxes, garden tools and everything else that doesn’t have a set place, garages can often become rooms of embarrassment we barely venture in to. And, that’s such a shame.

With garage conversions costing less than you think, the true value of that space could be unlocked and put to use in many fantastic ways.

Ways to convert a garage include:

  • Expanding a living or dining room
  • Adding a kitchen or bathroom
  • Adding a downstairs bedroom
  • Building a utility room
  • Creating a unique home gym
  • And many more!

With all these options, it’s no wonder that garage conversions are an increasingly popular way to improve a home. With space at a premium and house extension costs ranging from £25,000 – £160,000 (and beyond) they’re one of the cheapest ways to transform a home. As an added plus, you won’t have to give up any of your garden space either.

How much does an average garage conversion cost?

Garage typeCost + VAT
(Range low - high)
Average cost
Garage conversion cost£9,500 - £20,000£14,500
Integral garage conversion cost£7,500 - £12,600£10,000
Attached garage conversion cost£10,000 - £20,000£15,000
Detached garage conversion cost£15,000 - £25,000£20,000
Double garage conversion cost (Based on 36m2)£17,500 (integral) - £45,000 (detached)£29,000
Carport to garage conversion cost£10,500 - £15,000 £12,500
Partial garage conversion cost£5,500 - £8,500 £7,000
DIY garage conversion cost£2,500 - £6,000£4,250

For a breakdown of each cost we spoke to the online estimators at My Build Estimate – a professional estimating company monitored by the Royal Institute of Chartered Surveyors (RICS). This guide features the estimated garage conversion cost examples they provided.

Based on a 16m2 structure it will cost in the region of £7,500 – £20,000 to convert an integrated or attached garage into a habitable room. The average garage conversion cost is around £13,750.

This works out at a garage conversion cost per m2 of £469 – £1,200. When compared to the average cost per m2 of £1,250 – £2,500 for a home extension this shows just how much cheaper a garage conversion project can be.

For the prices in this guide, we have considered the following:

  • Unless otherwise stated, sizes are based on 16m2.
  • Garage conversion costs are based on an average specification.
  • Costs include basic fit out cost.
  • We have assumed insulation and screed will go above the existing slab.
  • Costs include blocking up existing garage door.
  • We have assumed services are suitable for delivering the full extent of the works.
  • No allowance for moving any meter boxes.
  • No allowance for cutting out doorways to external walls.
  • Costs include batten and insulation of existing external walls.
  • No allowance for additional kitchen and bathroom fixtures.

Types of garage conversion projects

garage conversion to gym cost

To understand how much your garage conversion could cost, below we’ve looked at some of the most common types of projects:

Attached garage conversion cost

Attached garages are the most common option and are one of the simplest garage conversion projects.

This includes any garage that is directly attached to the side or rear of the home, meaning it will usually have some basic electrics and any new pipework can be run from the main home. It also gives you the option to knock down a wall and extend an existing living space as well.

Converting an attached garage can cost from £10,000 – £20,000, with the cost to remove load bearing walls adding an additional amount on top.

Integral garage conversion cost

Similar to attached garages, integral garages are already connected to a home and therefore carry a cheaper cost.

These garages slot into the house, rather than appearing at the side or rear of a property, meaning they are already taking up valuable living space that you can now reclaim. They are the cheapest conversion option and if done well will look like a natural addition to your home that was always meant to be there.

Integral garage conversions cost between £7,500 – £12,600.

Detached garage conversion cost

Detached garage conversion cost

Garages that are not directly attached to a home are one of the most expensive conversions, although are still cheaper than most other single storey extension types.

Costs are higher because it’s harder to add electrics, water and gas as well as to build any trenches for these lines and pipework. A reinforced frame may also need to be added to the structure, further increasing prices.

Detached garage conversions are great for those that work from home and want a separate space for their office or business. They can even be turned in to playhouses for children, or a fun space for adults such as giving you a bar at home!

Detached garage conversions cost from £15,000 – £25,000.

Find your local garage conversion expert

Double garage conversion cost

Double garage conversion cost

With a much larger space at play, double garage conversions cost a fair bit more than single garage conversions.

As a plus, you’ll have around 30-36m2 to play with when designing your new space, within which you could create a new living room; combined kitchen and dining room; or a bedroom with an en-suite.

You could also split the space in half, choosing to keep part of the space as a traditional garage or storage space.

Integrated double garages cost around £17,500 to convert a 36m2 space.

Detached double garages cost approximately £45,000 to convert a 36m2 space.

Garage to bedroom conversion cost

With people moving home less and living longer, the way we use our homes changes over time.

For people getting into their later years, a downstairs bedroom can be the difference between staying in their own home or having to move out, and it’s why many people decide to convert their garage into a bedroom.

Alternatively, as families grow and our needs change, adding an extra bedroom downstairs can be a lot cheaper and easier than moving to a larger home.

Converting a garage to a bedroom can cost from £10,000 – £20,000, with additional costs if you want to add an en-suite or downstairs bathroom.

Partial garage conversion cost

If you don’t want to lose the ability to use your garage as a storage space, then one option is to conduct a partial garage conversion. This way the garage can be split to serve two purposes, separated by a stud wall. For example, it could be a storage space and a downstairs bathroom, or an extension to your living room and a space for utilities.

This can help keep the costs down as you can keep the existing garage door and only need to convert part of the space.

Partial garage conversions cost between £5,500 – £8,500.

Carport to garage conversion cost

One other interesting option to explore if you only have a carport is to consider converting that space into a garage. You already have the space pre-prepared and by turning it into a garage you’ll give your car extra security and gain a useful storage space. This won’t turn the garage into a liveable room – you’ll need to do a full single storey extension for that – but it’s a useful option if you need more storage space.

Carport garage conversions cost between £10,500 – £15,000.

Structural Changes and Building CostsRange lowRange high  
Removal of garage doors and replace £1,300£1,500
Door and window addition£1,200£1,500
Flooring (slab)£1,000£1,250
Stud wall addition£750£950
Addition of utilities : electric socket£90£100
Addition of utilities : pipes£1,000£3,000
Standard garage conversion total£5,000£7,800

Factors affecting the cost

Aside from the factors covered above such as size of the space, type of garage and distance from the home, there are other factors that can play a key role in determining the cost of your garage conversion. These include:

Quality of structure: If the current garage foundations, walls and roof are in disrepair then the price will increase to bring them back up to standard. Should the garage be especially poor quality, then it may be easier to knock it down and start again with a new structure.

Architect fees - architect working

Architect: It is not always necessary to use an architect for a garage conversion, especially if you wish for it to be a stand-alone room. However, if you want to knock down a wall and integrate the garage with other rooms, an architect can help draw up the perfect design. View our guide to architect fees for more information.

Heating: Whilst your garage will likely have basic electrics and lighting that can be upgraded, it’s unlikely to have any form of heating. Adding new radiators or underfloor heating will add to the cost so you should discuss with your contractor the best way to do this. In addition, you should check with them if your current boiler can cope with the extra demand.

RoomUnitCost + VAT (Range low - high)
Bathroom extension costPrice per m2 plus cost of bathroomAdd £2.5k - £5 to the total cost (average)
Kitchen extension costPrice per m2 plus cost of kitchenAdd £10k-£25k to total cost (average)

Purpose of the room: If you want to convert the garage into an office, living room or bedroom then costs will be at the lower end of the scale. However, if you’d like to turn the space in to a kitchen or bathroom then costs will increase to add water and gas, as well as the necessary white goods and fittings. Expect to pay £2.5k – £5 extra for a bathroom and £10k – £25k for a kitchen.

Garage door replacement: How you choose to replace the garage door will affect the cost. The cheapest option is to opt for a new garage door with a window, although this won’t offer the insulation or security options of adding a new wall. Adding a new wall and window is typically the best option to increase the value of the home and for overall aesthetics.

Removing load bearing walls: As we touched on above, if you opt to have a wall knocked down between the garage and current living space then this will be more expensive than adding a door between the two rooms. Our guide on the costs to remove a load bearing wall offers some excellent advice on the prices and timeframes to do this.

Find your local garage conversion expert

Planning permission and building regulations

Planning permission is not typically required to convert a garage into a habitable room as most projects are classed as permitted development. For detached garages it is more likely that planning permission will be needed. If in any doubt, check with your local authority.

Your work will be subject to building regulations, and you will need to attain a completion certificate for the work – this can be issued by your local authority or a private approved inspector. Contact them before work commences.

You should also read the deeds to your home to check that there are no terms mandating that the garage be kept as parking.

How long will a garage conversion take?

Depending on the type of garage you have, a conversion project will typically take in the region of 2 – 4 weeks. This is significantly quicker than other home extension projects.

What does a garage conversion involve?

What does garage conversion involve?

Although you already have an existing structure this doesn’t mean it’s fit for purpose. Walls in an integral garage are likely to be double-skin blockwork with a cavity, but it’s unlikely this cavity will have been insulated. Likewise, if the garage is attached then it’s likely that the external walls will only be single skin blockwork.

In either case, the walls will need to be made structurally sound and be insulated to the same standards as the rest of the house. This may include the need to make improvements to the existing foundations.

The floor of the garage will be below that of the rest of the house so sufficient insulation and a damp proof membrane (DPM) will need to be added before you lay the final finished floor.

The garage door will need to be removed, and the front wall filled in (with the same improvements to structure and energy efficiency). Most people opt for a bay window (often to attempt to match the one on the other side of the front door) but it may well be worth thinking about something a bit more ‘designed’ to get round potential privacy issues. A tall, narrow ‘slit’ window will bring in sufficient light but mean that you don’t have to worry about feeling a bit exposed to the street.

The internal door from the garage into the house (utility or kitchen) will be a 30-minute rated fire door. As the garage is becoming a regular living space, this can be turned back into a standard door.

The garage will have minimal electricals in place (usually enough for a fluorescent strip light and some sockets) and no heating or water. Therefore, this will need to be addressed depending on the future use of the room. There are additional elements of the job, from plastering through to decorating and joinery, which can add to the cost as well.

DIY garage conversion cost

Converting a garage will involve a range of different jobs to bring it up to liveable standards. It needs both careful consideration and significant building work. As such it may not be something you can complete as a DIY project, especially given all of the different specialists involved including bricklayers, window fitters, plasterers, electricians, joiners and more.

There’s also the added complication of how you will remove the waste materials, especially the heavy garage door. If you did wish to order the materials yourself, a DIY garage conversion can cost from £2,500 – £6,000.

To find a local, reputable professional in your area and get a personalised garage conversion prices, use our free search feature.

Key takeaways

  • Garage conversion costs per m2 are lower than other home extension projects.
  • The location and size of your garage plays a role in determining the price of your garage conversion.
  • Your intended use for the room will also vary the cost, especially if you want to use it as a kitchen or bathroom.
  • Converting a garage is a great way to add a downstairs bedroom for the elderly or less physically able, without the cost and hassle of moving.

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