Garage Conversion – Beginner’s Guide

A garage conversion could be a really easy and cheap way to make the most of your existing space and at the same time add value to your home. A well considered project could provide a 10%-20% return! However, this kind of conversion requires careful thought and planning and we hope our guide will make this a little easier for you.

Should you convert your garage?

Garages are generally used for storing household clutter that you no longer use or you think might come in handy ‘one day’ So if your garage is a wasted space where you simply pile up junk then maybe a conversion is the perfect solution to make your garage become a natural part of your home. You could add an extra bedroom, bathroom, extend your kitchen or even a home gym, office or cinema! The possibilities are endless and converting your garage could open up your home and bring in more light too. Just some advantages of converting a garage over a classic home extension is that your garden will not be destroyed by construction work and the garage is usually already attached to your house.

Do you need Planning Permission and Building Regulations Approval?

Probably not. While it is always best to check with your local authority, integral garage conversions do typically fall under Permitted Development, most of the work with a garage conversion is internal. However, there are always exceptions and if you live in a conservation area or a listed building, you will almost certainly require planning permission. You should check with your local authority - also, changing the facade or adding windows might need planning permission in your area. It’s recommended to have an informal meeting with your local planning officer before you submit your application. Some modern built garages are required to be retained as parking, which would need to be discharged. You’re also more likely to need formal permission to change the use of a detached garage.

A Building Regulations Approval will be required as your conversion classes as the ‘change of use’, and to comply with the building regulations, your garage conversion must:

●      be energy-efficient by having loft, wall and floor insulation,

●      be moisture proofed,

●      have good ventilation,

●      be fire-proofed and have escape routes,

●      be structurally sound,

●      have a damp-proof course,

●      have had all electrics safety tested.

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 register your conversion and carry out inspections throughout the project, then issue the final certificate on completion.

With more complex projects, you may submit full structural plans. This gives you peace of mind that building control has inspected the drawings and confirmed that your conversion will comply with all regulations. Once the garage conversion is finished a building inspector will come to check windows, doors, fireproofing measures, and foundations before providing a certificate of completion.

How much does a Garage Conversion cost?

This is hard to estimate as every conversion is different and starts from a unique starting point. However this project could make great financial sense because it’s significantly less than the value you could add to your home. Of course, costs will depend on the kind of space you’re creating and the quality of finish you want to achieve and costs would increase if there are structural changes, plumbing needed or utilities to be added.

Keep in mind the following factors, as these may increase costs:

●       the foundations need reinforcing

●       the walls, floors or roof are in poor condition

●       the ceiling height will need to be raised

●       design fees

●       planning applications

●       the services of a structural engineer

Will you need a designer for your Garage Conversion?

The answer to this question depends on the scale of the scheme, on the complexity of your project and budget constraint, but here are a few guidelines to help you:

●      Engaging an architect or architectural designer will mean expert advice and new ideas, as well as identifying creative ways to maximize the potential of your garage and establish a space that flows naturally into your home. He/she will also help in dealing with Building Control. Payment: £1,200 - £3,000.

●      Consider engaging a recommended builder.

●      Think about a company that specialises in garage conversions. They could charge a lot for their services, but they will have plenty of experience in terms of dealing with any planning issues.

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When converting a garage, concentrate on the following as these are the key jobs for a project like this:

1.    make sure the walls and roof are sound

2.    floor slab

3.    infilling the door

4.    wall and roof insulation

5.    windows and doors

6.    heating and electrics

What insurance do you need during a Garage Conversion?

If you are engaging a builder, they should have their insurance (make sure they have it before they start work). You will also need to inform your home insurance provider and, if your home insurer won’t cover you, you may need to take out specialist additional insurance during the work.

Key Works

1. Assessing the foundations for a Garage Conversion

If your garage foundations are found to be inadequate or absent (if the existing concrete slab is 200mm or less), you have two options: either a 1m footing wall will have to be dug and filled with concrete, or a 140mm x 100mm concrete lintel can be added into the wall, below ground level, on both sides. You can then build a new infill wall on top.

2. Insulation

As with any conversion you must make sure your new garage room is warm and energy-efficient. The simplest way to add insulation to the walls is with insulated plasterboard fitted to timber battens above the damp proof course.

Depending on the type of garage, you can insulate the walls in different ways:

●      Integrated garages are usually built to the same standard as the main house and the walls probably won’t need upgrading.

●      Attached or detached garages of single-skin construction can be insulated internally.

●      Buildings with cavity walls can have insulation blown into the gap, thus preserving the internal floor space.

●      For a part-conversion, retaining a parking space, you’ll need to erect a fully-insulated internal dividing wall that is designed to provide 30-minute fire protection.

When it comes to the roof, the simplest way to insulate it is at the loft level. With a pitched covering, 270mm of glass fiber quilt should be sufficient – 100mm between the joists, and the rest on top. Flat roofs tend to need one layer between rigid PUR insulation board and another below — the space in between flat roof joists however can’t be filled. A 50mm air gap must be left above for ventilation. The second layer underneath will drop the ceiling height a bit.

The floor may need to be leveled (consider a self-leveling liquid screed), damp-proofed with a suitable membrane, lapping into the damp-proof course, and insulated to achieve adequate thermal performance. When you bring your garage conversion floor level up to that of the rest of your house, you can use the existing concrete floor as a base, adding a solid or liquid damp-proof membrane before fitting a layer of insulation on top. Check with building control on how much insulation will be required. Also, this is a good time to think about underfloor heating within your garage conversion.

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3. Plumbing, Heating, and Wiring

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●      Make a thorough survey of the plumbing and wiring in case you need to break through the wall to install doors and windows.

●      Locate the main outflows for water and the soil outflow.

●      Check the garage for wiring in the walls and ceiling.

●      Is it possible to locate the garage on the current consumer unit.

●      An additional mains supply can be installed if necessary and this will require the installation of a separate consumer unit.

●      If you have a detached garage, the wiring will depend on power usage. In this case you should always consult an electrician.

●      Efficient LED downlights are a good choice for illumination, as they can be easily integrated into the new ceiling structure.

●      For heating, plumbing in a suitably sized radiator will be the cheapest solution – but slimline underfloor heating is a sleek alternative that can maximize the floorplan and free up wall space.

●      If you’re planning a kitchen or bathroom, you’ll need to account for hot and cold water supplies as well as drainage.

●      As ventilation could be an issue, openable windows, fitted with trickle vents, will be sufficient in most cases; if you’re incorporating a bathroom or kitchen, you’ll need a powerful enough extractor fan.

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‍NOTE! Avoid these common Garage Conversion mistakes:

1.    Don’t let your annoyance with the wasted space in your home rush you into starting work on a project that will eventually prove to be a mistake.

2.    Before hiring your contractors, explore your options and consider the options in detail so you don’t choose the wrong one.

3.    Don’t underestimate the cost of the project.

4.    Don’t ignore rules and regulations.

Good luck!

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