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Converting A Garage Into Living Space

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Garage conversions are becoming increasingly popular among UK homeowners wanting to make better use of their space. As the housing market continues to rise, people are becoming more creative when it comes to maximizing their living area.

Converting a garage into usable space is generally cheaper than buying a bigger home, and the possibilities are endless – gyms, offices, toilets, cinema rooms, living spaces – the choice is yours!

In most cases, planning permission is not needed to add value to a property, making a garage conversion an attractive option.

When undertaking any major home improvement, careful thought, planning and patience are a must. Without these, you could end up with an expensive disaster rather than the conversion of your dreams. At Permagard we’ve been helping people DIY it for years.

We take pride in providing comprehensive technical guides and market-leading products, equipping our customers with the best tools and knowledge.

So if you’re looking to increase your living space, considering a garage conversion, or even planning one, this garage conversion guide will provide you with everything you need to know

Table of Contents

Is it worth converting a garage?

Before you take any action, it’s important to ask yourself:

  1. If a garage conversion is worth the time and money. First, you need to consider whether you have the time to dedicate to the project.
  2. A DIY garage conversion is not a quick process, and rushing it could lead to costly mistakes. Additionally, garage conversions require a lot of work, as they are not built to the same standards as houses.
  3. Furthermore, think about how much use you’ll get from the conversion. If you’re only using it occasionally, it may not be worth the effort and money.
  4. Finally, you need to think about where you’ll store the contents of the garage. If you don’t have enough space, you may not be able to spare the space for the conversion.

How much does a garage conversion add to your house value?

Many homeowners are motivated to convert their garage for the added living space and potential increase in property value.

But does a garage conversion increase the value of your house? It depends. Some conversions can add up to 20%, such as bathrooms and bedrooms, while home cinemas, offices, and playrooms may not have as much of an impact.

In some areas, garages are highly desired and having one can add up to 5% to a property’s value. Before converting your garage, it’s wise to get a professional appraisal to ensure it won’t negatively impact the existing value of your home. 

Converting A Garage Into Living Space
Converting a garage into usable space is generally cheaper than buying a bigger home, and the possibilities are endless - gyms, offices, toilets, cinema rooms, living spaces - the choice is yours!

How much does a garage conversion cost? 

Cost is a major factor when deciding to convert your garage. Many guides attempt to give you a monetary value, which can be confusing.

Costs can vary depending on your location, but it is important to be aware of the factors that can influence the cost of the conversion. Knowing what to expect can help you to plan effectively and make any necessary adjustments.

Type of conversion 

The cost of a garage conversion largely depends on the purpose of the conversion. For instance, if you wish to convert it into a bathroom, you will need to purchase plumbing porcelain goods and shower fittings.

Whereas, if you are converting it into a bedroom, you won’t require extra fittings.

Exterior garage conversion

If you intend to alter the structure of the garage, then this is considered an extension and will require planning permission. This comes with associated costs, mainly involving an architect’s fee for drawing plans and submitting the permission.

Depending on the outcome, you may have to submit multiple applications which can incur a significant cost.

Is your garage suitable for conversion
Planning a garage conversion is an important home improvement project.

Is your garage suitable for conversion?

Before starting the planning process, you should check whether your garage is structurally sound and safe to convert. Over time, some garages may suffer from damaged foundations, worn brickwork, and other instabilities.

Also, garages built before 30 years may contain asbestos which can be hazardous when disturbed. To be sure, it is best to contact your local authority’s building safety department.

  • Planning a garage conversion is an important home improvement project. It requires meticulous planning to stay within budget, meet your needs, and ensure the conversion is of good quality. Before you start thinking about cosmetics and decorations, you should plan out the project in detail and be consistent in your approach. If something goes wrong, you may have to spend more money and time fixing the problem.
  • What’s your budget? Your budget will heavily influence what you can do with the conversion. Make a detailed budget that includes every stage of the project, with both material and labour costs. You should also include the cost of hiring an architect, if necessary, and any other third parties. It’s also wise to set aside extra funds for potential overspending.
  • What do you want to achieve? Before you begin any work, you need to be certain about your goals for the space. For example, if you’re making a home gym, think about the equipment you want to include and whether the space will be able to accommodate multiple people training at once.
  • DIY garage conversion vs professional build: You can do the conversion yourself, hire a tradesperson or contractor, or employ architects to design it and construction professionals to carry out the work. Each option has its pros and cons:




Benefit from the knowledge of experienced professionals.

Work is guaranteed and insured.

You don’t have to spend your time doing manual labour.

Can be very costly

Project completion time depends on your contractors schedules and commitments


Usually a lot cheaper as labour costs are reduced

You can go at your own pace and complete the project in whatever time you wish

Personal satisfaction

Someone performing A DIY conversion would likely be doing this for the first time with no experience

Requires a lot of planning and work

Work is not professionally guaranteed

Garage waterproofing 

Garage waterproofing is an essential part of transforming a garage into a living space. The construction standards of garages are much lower than those of habitable properties, so waterproofing is vital to avoid costly damage and render the conversion uninhabitable.

  • Epoxy floor coating is a great way to prevent dampness from coming up through the garage slab and ruining the final floor finish. If a new slab is being laid, this coating allows you to move forward with the project without waiting for the slab to dry.
  • Tanking slurry is an effective solution for waterproofing garage walls, as it creates an impermeable layer to stop water from entering. Products such as PermaSEAL Tanking come in grey and white, and a tanking brush is needed to apply it.
  • Wall Floor Joint where the wall and floor meet is often a weak point in terms of leakage. To create a reinforced fillet joint, you should chase out the floor to a minimum of 20mm x 20mm at the wall floor joint, and cut into the wall if possible.

After flushing out the chase and removing any debris, apply one coat of tanking slurry 100mm up the wall and 100mm across the floor. Once the slurry is still tacky, add PermaSEAL Fillet Seal over the tanking slurry and into the chase to form a cove from the wall to the floor.

Ventilating a Garage

When turning a garage into any kind of living space, ventilation is a must. Without proper ventilation, condensation, black mould, health issues, and bad odours can occur. Fortunately, there are a variety of ways to ventilate a garage conversion.

  1. Windows are great for ventilation, as they can be placed anywhere. A combination of skylight and wall-level windows is especially effective, as the fresh air coming in from the wall-level windows pushes the old, stale air upwards and out through the skylight. To make sure the windows are providing adequate ventilation, they should be at least 1/20th of the total area of the space.
  2. Trickle vents are another option. These small openings in window frames and sashes let in just enough fresh air to provide a regular supply without losing too much heat.

If the conversion involves a bathroom, shower, or gym, an anti-condensation vent, such as:

  • The Perma-Vent, is necessary. For these kinds of conversions, more air change is required than for a home office or cinema.
  • The Vent-Axia Heat Save Ventilation unit is also a great option as it expels damp air and separates heat energy for reuse.

Garage conversion insulation requirements

Insulating and waterproofing your garage conversion is essential. The structure of a garage is usually a single skin blockwork, with no thermal buffer to prevent thermal energy from entering or leaving. Insulating your garage will make it more comfortable and help reduce heating costs.

  • Concrete garage floors usually have poor thermal conductivity, making them hard to warm up, even with ambient heating.
  • Floating Floor an affordable flooring solution is to use a floating floor. This involves laying down solid flooring over a layer of insulation. It’s easy to install and replace individual tiles, though it may reduce the room’s depth by up to 5 inches.
  • Epoxy paint is another option for garage flooring. It creates a hard-wearing seal and is resilient to abrasions, scratches and chemicals, making it ideal for garages or gyms. It’s also easy to clean.
  • Garage conversion wall insulation Wall insulation is key when it comes to retaining heat inside your garage space. Most garages have at least one wall facing the outside, with detached garages being exposed on all four sides to weather, wind and rain.

The typical single-skin blockwork of a garage wall is never insulated so failure to properly treat them will result in a significant loss of heat. Garage conversion wall insulation is critical for energy economy and comfort, so you should achieve at least a 0.28 W/m2K U-rating when insulating the walls.

External wall insulation
When converting a garage, you can choose to insulate the interior or exterior walls.

External wall insulation

Wall insulation is essential for retaining heat inside a garage space. Most garages have at least one wall facing the outside, while detached garages can be exposed to rain, wind, and weather on all four sides.

The typical single-skin blockwork of a garage wall is not insulated, so failing to treat them correctly will lead to a huge loss of heat.

Therefore, garage conversion wall insulation is essential for energy efficiency and comfort, and you should aim for a U-rating of 0.28 W/m2K when insulating the walls.

When converting a garage, you can choose to insulate the interior or exterior walls. For detached garages, external insulation is ideal because you can achieve a uniform exterior without sacrificing interior space.

This is usually done by attaching insulation panels and render or exterior insulation boards to the outer walls. This prevents coldness from travelling through masonry, which is known as cold bridging.

  1. Internal insulation is usually used for semi-detached garage conversions since adding an extra layer on the exterior would look strange compared to the main building. This is usually done by placing insulation panels or rock wool between the wooden stud wall and the blockwork. Insulation spray foam, insulated plasterboard, or fibreglass rolls can be used as an alternative to panels.
  2. Garage Door Many people choose to keep their garage doors when converting, but a large metal garage door is highly thermally-conductive and can easily let heat escape or make the interior too hot during summer. Polystyrene foam, panel insulation, or reflective foil insulation are all common materials for garage door insulation.

It is important to remember that lightweight reflective foil is usually the best option, as heavier materials can overload the lifting mechanisms and springs of the door.

Insulating a pitched roof garage conversion

Insulating a pitched roof garage conversion is essential for heat retention. Heat rises naturally, which is why it is important to stop it from entering or leaving the garage roof. If you neglect to do this, it will result in expensive energy bills and a living space that never gets fully warm. If your garage has a pitched roof, you can insulate it in the same way as a loft – by installing thick fibreglass panels over the roofing rafters.

When it comes to a flat roof garage, the insulation methods are slightly different. You can choose either a cold or warm roof system.

  • A warm roof system involves placing the insulation materials on top of the flat roof deck before the roof covering is done. This is beneficial as you don’t lose any ceiling space, as the insulation is closer to the roof layer – making the roof space ‘warm’.
  • A cold roof system involves fitting insulation between the joists beneath the roof deck. This is simpler to do, but it does reduce the interior ceiling space. It’s also important to have a gap of 50mm between the insulation panels to ensure ventilation and avoid condensation.

Soundproofing is often overlooked when converting garages into living spaces. If you’re turning your garage into a bedroom, office, or home cinema, it needs to be free from any outside noise. To ensure this, you should create a ‘room within a room’.

This is done by installing timber wall frames in rectangular rows along the inside of each wall and ceiling.

The gaps in the timber frame are then filled with acoustic wool to act as the main sound absorber. On top of this, specialist foam acoustic panels are added, followed by a layer of plasterboard over the insulation of your choice.

How can we help?

Contact Property Saviour and get valuable details for your garage conversion. We provide expertise and guidance to help make the process easier. No need to worry about difficult tasks, we are here to support you.

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