Although a garage conversion may feel like an easy way to extend your living space, there's more to it than simply decluttering and adding some internal walls and new flooring.
But, with many garages under utilised, and the cost of extensions rising, using the space you already have can certainly hold appeal, and be a quicker way of adding more rooms.
In this guide to garage conversions, we explain exactly what's involved so you can proceed with confidence when converting your garage into extra floorspace.
Garage conversion or extension?
Whether you have an integral or detached garage, unlike some larger extensions, garage conversion ideas can often be exempt from needing planning permission.
“Garage conversions can be remarkably versatile, and actually extremely affordable,” says Andy Simms, construction consultant at MyBuilder.com. “Depending on where the garage is located in comparison to the rest of your rooms, they can provide a multitude of great spaces, as well as providing extra storage.”
Garage conversions also have other benefits when compared to extensions. They are usually quicker and easier to carry out, and while this doesn’t mean garage conversion costs are always cheap, they are most certainly one of the more cost-effective ways to add some square meterage to your home.
Not using up valuable garden space can also be a benefit of a garage conversion. And, a lot of the work can take place without it affecting your existing home – even if you have to add an access point from the house into the garage.
Generally, the decision on garage conversion or extension will come down to a variety of reasons, including how much space you need, whether your garage is fit for purpose, or if demolishing it and adding a new side extension may be a better option.
However, before getting carried away, it’s important to check whether your garage is suitable for conversion.
“You’ll need to consider how the garage is constructed and what you want to use it for,” says Jude Tugman, founder of Architect Your Home, “as these criteria will impact on the cost of the conversion.” In addition, the changes you make may also affect whether your garage conversion will still fall under Permitted Development or will require full planning approval, a subject we’ll cover in more detail later on.
Need more advice or inspiration for your project? Get two free tickets to the Homebuilding & Renovating Show.
With almost a decade of experience on the front line in construction as a multi-trader, Andy has a vast amount of experience in residential conversions and extensions.
Are your foundations and roof suitable?
It’s common to think that as your garage has walls and a roof, it will be strong enough to work as a converted room. But this isn’t always the case.
“You shouldn’t assume that the existing foundations are adequate,” says Steven George, partner and studio lead at George & Co. “Trial holes should be carried out at the bringing of the project to inspect the existing foundations, as they will need to take the additional load.
“Otherwise you’ll have to underpin the existing foundations,” he explains, “which is labour intensive, and expensive. Before starting any garage conversion, you’ll need to establish how the existing garage is constructed, particularly if you are looking to add an infill wall in place of your garage door.”
An infill wall is usually one of the key parts of a garage conversion, offering the change to replace the garage doors with a wall that often comprises a window, or entry door.
The most common approach is to infill in a way that matches the home, either by building in matching bricks, or building in block and matching the exterior cladding. Adding a door or window can also help ease the load on the foundations, as well as bringing in natural light.
If the existing concrete slab is 200mm or over, this is generally adequate to extend straight up with new brickwork. If the existing slab is not sufficient however, there are typically two options. Either a 1m footing will have to be dug and filled with concrete, or a 140mm x 100mm concrete lintel can be added into the wall on both sides below ground level. The new infill wall can then be built on top of that.
Establishing the strength and types of foundations you have is even more important if you are considering extending over a garage to add a second storey, as this greatly increases the load exerting pressure on your foundations. You’ll also need to consider further building regulations for thermal and sound insulation if you decide to add an additional storey to your garage conversion.
Will you need to replace your garage roof?
Although you may assume you need to factor in budget for garage conversion roofing into your plan, it’s not always the case, say the experts.
“In the first instance, an inspection is wise to see how long a life your garage roof has left,” says Steven George. “If you discover that water is lying in pools on a flat roof, then this has the potential to cause problems in the new space beneath. The roof will then of course need repairing, and the underlying fabric of the structure checking for damage.
“Occasionally it is also necessary to replace the entire roof,” confirms Steven. “However, this is sometimes a welcome discovery – swapping a flat roof for a pitched design for example, can help tie the new space in with the rest of the house and leave you with a more aesthetically pleasing result.”
Steven George is a partner and design lead at award-winning architects George and Co. Working across Wales and the South West, the practise has also appeared on television in a number of different home renovation programmes.
Understanding windows and door requirements
As part of the building regulation requirements, under under approved document Part B, you may be required to install a window or door that acts as a fire escape route when converting a garage.
Building control officer, Paul Hymers, explains.
“Attached garage conversions are usually accessed by a hallway door, providing a safe means of escape to outside, but if you can only enter this new room from another (outer) room, it defines it as an inner room.
“Because a fire in the outer room could prevent your escape, the inner room will need an alternative escape route," advises Paul. "This can be a door or window, and so the role is often performed by the window or door replacing the garage doors at the front. But, escape windows have minimum criteria," he notes. "If your inner room is a kitchen, en suite, cloakroom WC or bathroom then it doesn’t need an alternative exit.”
In half garage conversions, where only part of the garage is being used as habitable space, the wall separating the two should also be fire-rated to 30 minutes.
Any window installed is also subject to certain criteria, including its height from the floor, how it opens and the size of the openable section. As a rule, the width and height should be no less than 450mm, it must be a maximum of 1100mm from the floor level, have an openable area of 0.33m2 at the bottom of the window, and generally be side-hung.
However, do bear in mind that windows within garage conversions under Permitted Development are largely only allowed in the section replacing the garage door. Any new windows added to the side may require a planning application.
Insulation for your garage conversion
When it comes to the insulation requirements for your garage conversion, build expert, Mark Stevenson covers this in more detail in our guide to insulating a garage conversion.
However, it helps to understand that you will potentially need to insulate in three different places. Your walls, floor and roof may all need insulation in order to keep your new space warm. This will all impact your timeframe and budget, and could also impact the overall floor space you are left with if you need to add internal wall insulation, or alter the floor or ceiling heights.
Adding external wall insulation for example, is not usually recommended in garage conversions as it can cause issues externally with wall thicknesses.
"You will need to consider if you are able to afford to lose space when you start adding in insulation thicknesses to the walls and floor," confirms Steven George.
“Will the ceiling height need to be raised if you’re increasing the floor level? In general, you need around 2.2-2.4m of headroom once the floor has been raised to 15cm above the external ground level," he adds. This can also influence your purchasing when deciding which garage conversion flooring to install.
What ventilation guidelines will you need to follow?
"Home ventilation is vital for a garage conversion, otherwise you're just building a box that's going to sweat." says Mike Taylor from Taylor + Co Architects.
Installing an openable window is an easy way to purge ventilation. The opening should have an area of at least 1:20 of the floor area of the room it serves, whereas bathroom windows can be any openable size. Trickle vents should also be incorporated into the window framework to provide background ventilation.
If your garage already has air bricks, these should not be covered up, and be mindful of building regulations Part F regarding ventilation if your garage conversion will include a bathroom, kitchen or utility room, as you'll likely need an extractor unit to ensure moist air can be removed from the room.
Plumbing and electrical changes
Garages often house electricity meters and distribution boards, making it easy to install electrics there. However, new lights, sockets and electric radiators could put additional strain on older consumer units, which may mean you need to add new consumer unit costs to your budget.. If you're installing wiring for a detached garage, it can be run through an underground channel.
If the garage is to be another habitable room in your house, its own miniature circuit breaker is probably enough, although you should consider adding at least one new 20-amp circuit. Or, if necessary, an additional mains supply can be installed, but this will also require the installation of a separate consumer unit.
Whether or not you need plumbing will come down to how your new space will be used. While living rooms or games room ideas won't necessarily need a water supply, “if you are considering using your garage conversion for a utility room or garage conversion bedroom with ensuite, you’ll firstly need to look if there is any drainage locally to the garage,” says Steven George.
A drainage survey should be carried out to locate the main outflows for water (as well as the waste pipe if you're installing a WC). Consider how far the garage is from the mains and waste pipes of the main house as the further the distance, the more your costs will increase on both a labour and materials perspective.
Planning and building regulations when converting a garage
Unlike planning permission for garages that are new, which do require full planning permission, the majority of integral garage conversions tend to fall under Permitted Development, meaning planning permission is not required.
In fact, according to architectural specialists Resi, only 10% of garage conversions will require planning permission. However, it is still best to check with your local authority, as there are number of occasions when you still might fall under certain jurisdiction.
- Stand-alone vs integral: If your garage if you are converting a stand-alone garage as opposed to an integral one, then you may have to apply for a change of use
- Conservation areas and listed buildings: If you live in either, you will almost certainly need planning permission.
- Planning conditions: You should also check for any planning conditions attached to the house or garage when it was originally constructed, as in some cases garages will be required to remain as spaces for parking. If there are conditions, an application will need to be submitted to remove them.
- Garages on new-build estates: “If you are also considering converting a garage on a new build, you will also need to speak to your local authority,” says Steven George. “In general, planning departments remove permitted development rights on new build housing estates, meaning you would also need to apply for planning permission to convert a garage.”
Even if the conversion falls under Permitted Development, applying for a Lawful Development Certificate is a good idea, particularly if you aim to re-mortgage or sell the house in the future, as it will protect you under any changes that may occur post conversion.
Building regulations are required and here’s why
A garage conversion will most certainly need building regulations approval. As previously mentioned, you will need to adhere to the various approved documents relating to thermal performance, acoustics, fire safety and ventilation.
A building notice or full plans application will need to be submitted to building control as part of this process. Your local building control department will then register the conversion and carry out inspections throughout the project, then issue the final certificate on completion.
Design and build options for your garage conversion
The type of professionals you need to hire for a garage conversion will largely depend on the size and scope of your project, and how many changes you need to make to the exterior and interior.
If you need to make changes to the foundations or create new openings, you will almost certainly need the services of a structural engineer, but when it comes to other professionals you do have options.
Do I need an architect?
Whether you choose to hire an architect, or an architectural technologist or not, is very much a personal decision that should be based on the scale and complexity of the project, although there are of course benefits to calling in expert help and a fresh set of eyes.
“Architects will look at the house as a whole, helping to create a holistic design that will focus on the need for the work as well as ensuring it dovetails with your existing home,” says Steven George. “ An interior designer can also be a great option, as much of the work often revolves around internal detailing and storage ideas.”
A design professional will also have useful trade contacts and will have experience in dealing with Building Control which could help to make the process more seamless and avoid any delays.
DIY vs builder
Some people choose to come up with a design themselves and carry out a DIY garage conversion – a good option for those with limited funds and the spare time to get stuck in, although you will need to use certified electricians and plumbers where required.
But, if your DIY skills are more limited, you will need to find a builder to take on the work – especially if you are considering adding another storey to your garage conversion.
Another option is to use a garage conversion specialist. These companies usually have a wealth of experience and will be able to deal with any planning issues surrounding garage conversions, as well as building regulations.
But, as with all of the above options, be sure to view completed projects and speak to past clients before finalising your design and build team for your garage conversion.
Choosing your external finishes
The best converted garages usually look like part of the rest of your house, the exception being partial garage conversions. These are where the front of the garage remains unchanged (both internally and externally), while the rear section of the garage is incorporated into the house. This allows you to retain some garage storage space, while gaining a little extra living space.
Depending on the design of your existing home, you may be keen to ensure the materials used for the cladding and roof (where there is one), windows and doors match or tie-in with those on the main house to create a seamless finish.
Alternatively, you might wish to adopt a contemporary take on the design and highlight the garage as a new element of the house, choosing metal cladding or rendering to contrast with brick.
Opting for a new external finish can also help overcome any issues surrounding how the old opening for the garage door is concealed, as a badly bricked up opening is a design disaster.
“Blockwork and render are usually the easiest solution for this,” says Steven George, “as you can hide the original structure with the cement render. Brickwork should really be toothed into the existing, otherwise you will see the bricks butt joint, and this is a little bit unsightly.”
Timings for your garage conversion
The length of time your garage conversion will take comes down to the level of work involved.
According to Andy Simms, if you've established your foundations and roof don’t need any work, “a simple garage conversion can be turned around in a relatively quick time period – sometimes just two or three weeks, and once the garage is empty, the work tends to begin quite unobtrusively.”
Of course, each project is different, and if you do need work done to the roof or foundations you will need to add this onto the timescale. Likewise if your garage conversion forms part of your plans for renovating a house, you’ll need to factor the work into the overall schedule.
FAQs
When shouldn't you convert a garage?
While a garage conversion is, in the majority of cases, a brilliant way to add space and value to your home, there are certain instances where it might not be a viable option. Think about the following before you proceed:
- Will the work mean one or more existing rooms will frequently be rendered unusable by building work and will these rooms impact too much on your daily life?
- Remember that you will be held responsible for the legality of work done on your property. Time and energy will be required supervising work, being present to allow tradespeople access and making design and other decisions. Can you allocate time for the project?
- Might the cost of reinforcing foundations, replacing a garage roof, or applying for planning permission mean you are paying more than you expected, and facing a longer project time that makes the project unfeasible?
Will a garage conversion add value to your home?
Increasing your home’s usable floor area will likely boost its cash value, and a garage conversion can add as much as 20%, say Checkatrade, depending on what it’s converted into, with extra bedrooms with en-suites adding the most value.
But, it will also come down to your location and what the housing market in your area looks like. Ask yourself does your home really need extra room? Do you have a drive to park on, or is there copious amounts of on-road parking? What is the price ceiling in your area?
These factors will affect how attractive your home is to potential buyers and may affect the overall amount that converting a garage adds to the value of your home. Be sure to discuss your plans with a local estate agent to see if your plans will add value and if so how much so that you can ensure your budget doesn’t exceed any potential return on your investment.
Still not entirely sure what you could do with the space if you converted your garage? If your garage is on the smaller side, why not take the opportunity to indulge in a bespoke boot room for keeping muddy shoes and pets away from hallways? Or, if your garage is attached to your kitchen, could a back kitchen or pantry give you the extra space and storage you crave?
