Picture this: your home feels a bit cramped, and you're dreaming of extra living space. Maybe your garage is a cluttered storage space for old bikes and boxes, or perhaps you're considering building a brand-new extension to your main house. Both options can transform your property, but the big question is – Is a garage conversion cheaper than an extension?
In this article, we’ll dive into the details, comparing costs, processes, and practicalities in a friendly, conversational way. Whether you're eyeing a cosy new room from your existing garage or a spacious extension, we’ll help you decide what’s best for your budget and needs. Let’s explore how a garage conversion project or an extension can create that extra space you’re craving!
A garage conversion takes your existing structure—be it a single garage, attached, or detached garage—and turns it into a functional, habitable room. Instead of parking cars or storing junk, consider using the space for a home office, gym, or utility room. The beauty of converting a garage lies in using the garage’s existing foundations, walls, and garage roof, which cuts down on construction costs. Typically, the process involves insulating garage floors and walls, bricking up the garage door, and adding windows for natural light. For a standard single garage, you’re looking at adding 15-30 square meters of living space, making it a versatile option for many homeowners looking to maximise their property without major upheaval.
Why go for a garage conversion? For starters, it’s often quicker and less invasive than building an extension. You’re working with an existing structure, so there’s no need to dig new foundations or disrupt your garden. A successful garage conversion can boost your home’s value by up to 20%, turning unused garage space into a valuable habitable space. Whether it’s a detached garage becoming a guest annexe or an integral one morphing into a playroom, the possibilities are endless. Plus, it’s eco-friendly—reusing the existing structure means less waste and fewer materials. For those craving extra living space without a massive project, this is a no-brainer.
If a garage conversion feels too small-scale, a home extension might be on your radar. Extensions add brand-new space to your main house, offering flexibility but also a bigger commitment. Let’s unpack what they’re all about.
Extensions come in various shapes and sizes. A single-storey extension might add a kitchen or dining area, while a double-storey one could include bedrooms or bathrooms upstairs. You could extend over a garage, out the back, or even wrap around the side. Unlike a garage conversion, extensions require new foundations and a roof covering, which impacts costs. They’re ideal for those needing substantial new space that blends seamlessly with the main house, but they demand more planning and investment than converting a garage.
An extension shines when you want a custom-designed space tailored to your needs. If your garage conversion space wouldn’t cut it—say, for a large family room or multiple rooms—an extension offers more square footage and design freedom. It’s also a chance to enhance your home’s layout, like opening up the back for a modern kitchen-diner. However, extensions often mean longer construction times and more disruption, so you’ll need to weigh whether the extra space justifies the effort compared to a simpler garage conversion project.
Let’s talk money—because that’s the heart of the question. A garage conversion is generally cheaper than an extension, but let’s break down the numbers to see why.
In 2025, a garage conversion cost for a single garage in the UK typically ranges from £10,000 to £30,000, depending on size and finishes. Per square meter, you’re looking at £625-£1,250, making it a budget-friendly way to gain extra living space. For a detached garage, costs might creep up to £15,000-£25,000 due to extra insulation or structural work. Key expenses include insulating the garage conversion wall, insulation, bricking up the garage door, and installing new flooring. If you’re handy, a DIY garage conversion project can shave off labour costs, though professional help ensures compliance with building regulations.
Several elements influence the final bill for a garage conversion. Garage conversion, wall insulation, and roof insulation are big ones, often costing £1,000-£2,000 to keep the space cosy and compliant. Bricking up the garage door and adding windows for natural light can add £500-£1,500. If you’re turning the space into a utility room, plumbing and electrical wiring (including a separate consumer unit or miniature circuit breaker) could add £1,000-£3,000 to the cost. Hiring a garage conversion specialist versus going DIY also affects the budget—specialists ensure a polished finish but come at a premium.
Extensions are pricier. A single-storey extension averages £40,000, with larger or double-storey projects hitting £124,000-£173,000. Per square meter, expect £1,800-£3,000, significantly higher than garage conversions. Costs depend on size, materials, and complexity—think new foundations, roof covering, and integration with the main house. If you’re in a high-cost area like London, prices can skyrocket further.
Extensions rack up costs due to their ground-up nature. New foundations and a flat roof or pitched roof are major expenses, alongside structural engineer fees (£500-£1,500) and potential party wall agreements with neighbours (£1,000+). Planning permission fees and higher material costs also add up. Unlike a garage conversion, which leverages an existing structure, extensions are essentially new builds, so you’re paying for everything from scratch—bricks, windows, and all.
It’s clear: a garage conversion is typically cheaper than an extension. With costs averaging £15,000-£25,000 versus £40,000+, conversions save money by using the existing garage’s foundations, walls, and garage roof. You’re not starting from zero, which cuts material and labour costs dramatically. For most homeowners, a garage conversion delivers extra space at a fraction of the price, making it ideal for budget-conscious projects. Extensions, while offering more space, come with a heftier price tag that’s harder to justify unless you need a major addition.
Before you start hammering, let’s talk red tape. Both projects involve regulations, but garage conversions often have an easier path.
Great news: most garage conversions don’t require planning permission if they’re internal and don’t enlarge the building. This applies to single-storey garages and partial garage conversions alike. However, if your home is in a conservation area or is a listed building, you might need listed building consent or to gain planning permission. Always check with your local authority to avoid surprises. A lawful development certificate can also provide peace of mind, proving your project complies with permitted development rights.
Extensions are more likely to need planning permission, especially if they exceed permitted development rights or alter the home’s footprint significantly. If you’re extending in a conservation area or a listed building, expect extra scrutiny. The process involves submitting plans to your local authority, which can take weeks and cost £200-£500 in fees. Unlike garage conversions, extensions often face stricter rules due to their impact on the property and surroundings.
Even if planning permission isn’t needed, building regulations are non-negotiable for safety and compliance.
Converting a garage into a habitable room means meeting strict garage conversion building regulations. These cover insulation, ventilation, fire safety, and structural integrity. Your local building control department will inspect the work, so factor in a building notice (£100-£300) or full plans application. A building control officer ensures the garage ceiling, floors, and walls meet standards, especially for fire safety and insulation.
Extensions also need building regulations approval, covering everything from foundations to roof insulation. Because they’re new builds, inspections are more extensive, checking structural stability and energy efficiency. This can add time and cost compared to a garage conversion, where the existing structure simplifies some checks.
Your garage’s existing setup plays a big role in the conversion process. Let’s look at what’s involved.
Most garages sit on a concrete slab, but not all are suitable for habitable space. The garage’s existing foundations must support the new use, which might require a structural engineer to assess (£500-£1,000). If the foundations are shallow or weak, you’ll need to reinforce them, adding to the garage conversion cost. Thankfully, most garages are built to handle car loads, so they’re often sturdy enough for conversion.
Garage floors often sit below the external ground level, requiring raising and damp-proofing to meet regulations. This involves adding a damp-proof membrane and insulation, topped with a final floor covering like laminate or tiles. Expect £1,000-£2,000 for this step, depending on the size and materials. Proper flooring ensures your newly converted space is warm and dry.
Whether your garage has a flat roof or pitched roof, roof insulation is critical for energy efficiency. Adding insulation under the garage roof keeps the space warm and meets building regulations. This can cost £500-£1,500, depending on the roof type and materials like insulated plasterboard.
Garage conversion wall insulation is another must. Most garages have single-skin walls, so you’ll need to add insulated plasterboard or cavity insulation to prevent heat loss. This step, costing £1,000-£2,000, transforms the space into a cosy habitable room that’s up to code.
Feeling handy? A DIY garage conversion project can save big bucks, but it’s not for everyone.
A DIY garage conversion involves tasks like insulating walls, installing new flooring, and bricking up the garage door. You’ll need tools, materials, and some know-how—think £5,000-£10,000 in materials for a basic job. However, critical elements like electrical wiring or structural changes require professionals to meet building regulations. Always get a building control officer to sign off, even for DIY projects, to ensure safety and compliance.
DIY saves on labour costs, which can be 30-50% of a garage conversion cost. It’s also satisfying to create your own new space. But mistakes can be costly, and non-compliant work might need redoing. If you’re not confident, hiring a garage conversion specialist ensures a polished, regulation-compliant result.
Safety is paramount when turning a garage into a living space.
Building regulations demand fire safety measures, like an alternative escape route (often a window) for your converted garage. If the new room is an inner room (accessed via another room), fireproofing is even stricter. Fire-resistant materials and smoke alarms are non-negotiable, ensuring your habitable space is safe for use.
Electrical wiring needs upgrading, often with a separate consumer unit or miniature circuit breaker for the new space. This ensures the converted garage meets modern safety standards, costing £1,000-£2,000 for professional installation. Don’t skimp here—faulty wiring is a fire hazard.
A garage conversion can add significant value, often 10-20% to your home’s price, especially if it creates a functional habitable room. Partial garage conversions, keeping some storage space, add less but still boost appeal. Extensions also add value but at a higher cost, making conversions a more cost-effective choice for many.
Are you ready to take the plunge and transform your garage into a warm, welcoming living space? Well, look no further! The Conversion Guy is committed to providing you with a garage conversion experience that is unparalleled.
With over 40 years of experience in garage conversions, we are looking forward to helping you turn your garage into a functional and beautiful space! We love talking conversions, so be sure to get in touch today or book a free consultation and start your journey towards a more spacious, versatile home.