If your home is starting to feel a bit tight, you’ve probably weighed up the two obvious options: convert the garage or build an extension. Both can transform how your house works for you — but they’re very different projects in terms of cost, disruption and the kind of space you end up with.

As a family-run building firm based in Burntwood, we’ve done plenty of both across Staffordshire and the West Midlands — from Cannock and Lichfield to Walsall and Stafford. Here’s an honest comparison to help you work out which route is right for your home and your budget.

The key differences at a glance

  • Cost: a garage conversion is usually around half to two-thirds the cost of an extension of the same size.
  • Time: conversions typically take 3–6 weeks; extensions often run 3–5 months from design to finish.
  • Space: a conversion works with what you’ve got; an extension adds brand-new footprint.
  • Planning: most conversions don’t need planning permission; many extensions do.
  • Disruption: conversions are mostly contained to the garage; extensions involve groundworks, scaffolding and more mess.

Cost: the conversion usually wins

The biggest single difference is money. With a garage conversion, the shell of the room already exists — walls, roof and foundations are done. You’re paying to insulate, damp-proof and fit out the space, not to build it from scratch.

In 2026, garage conversions in our area typically come in somewhere between £900 and £1,800 per square metre depending on spec, while a new single-storey extension generally runs from around £1,900 to £3,300 per square metre once you factor in foundations, structure and roofing. We’ve broken both down in detail in our garage conversion cost guide and our single-storey extension price guide.

In plain terms: a typical single garage conversion might cost £12,000–£20,000, while a modest extension of a similar size could easily be double that.

Time and disruption

A straightforward garage conversion usually takes three to six weeks on site, and because the work happens inside an existing structure, day-to-day life in the rest of the house carries on largely as normal. No digging up the garden, no scaffolding across the kitchen window.

An extension is a bigger undertaking. Once you add design work, structural calculations, possible planning approval and the build itself, you’re realistically looking at three to five months — sometimes longer for larger or more complex projects. The results can be fantastic, but it’s worth going in with your eyes open about the disruption along the way.

Planning permission and building regulations

Most garage conversions in Staffordshire fall under Permitted Development, meaning you won’t need planning permission — though there are exceptions for listed buildings, conservation areas and homes where permitted development rights have been removed. Building Regulations approval is always required, covering insulation, ventilation, fire safety and damp-proofing.

Extensions can also fall under Permitted Development if they stay within certain size limits, but larger builds, side extensions and anything on a corner plot will often need a full planning application through your local council. That adds time and a little cost, and there’s always a small risk of refusal or conditions being attached.

How much space will you actually gain?

This is where the extension fights back. A garage conversion can only ever give you the footprint of your garage — typically 12–16 square metres for a single garage. That’s plenty for a home office, snug, playroom or extra bedroom, but it won’t give you a big open-plan kitchen-diner.

An extension is designed around what you want. If your dream is a large family kitchen with bifold doors onto the garden, a conversion simply can’t deliver that — and an extension is worth the extra investment. You can see the full range of building services we offer, from extensions to full refurbishments.

Which adds more value?

Both add value when done properly. A well-finished garage conversion typically adds more value than it costs, precisely because the outlay is lower — it’s one of the best-value improvements you can make. A quality extension can add more in absolute terms, especially where it creates an extra bedroom or a standout kitchen, but the higher build cost means the margin isn’t always bigger.

One honest word of caution: if off-street parking is scarce on your road, losing the garage can put some buyers off. It’s worth thinking about how your street parks before you commit.

So which is right for you?

A garage conversion is probably the answer if you want extra space on a sensible budget, you rarely use the garage for a car anyway, you’d like the work done in weeks rather than months, and a room of 12–16 square metres suits what you need — an office, gym, snug or bedroom.

An extension makes more sense if you need genuinely more footprint, you’re set on a large open-plan living space, your garage is detached and awkward to integrate, or you’re planning a bigger reshape of the whole ground floor.

And sometimes the honest answer is both, done in stages — we’ve helped plenty of Staffordshire homeowners convert the garage first, then extend later when budget allows.

Frequently asked questions

Is a garage conversion cheaper than an extension?

Almost always, yes. Because the structure already exists, a conversion typically costs around half to two-thirds of what a similar-sized extension would.

Can I convert a detached garage?

Yes, though it’s a slightly bigger job than an integral garage — you may need to run services out to it, and planning rules can differ. It can make a brilliant home office or annexe-style space.

Will either option need Building Regulations approval?

Yes — both conversions and extensions must comply with Building Regulations. A reputable builder will handle the process and make sure everything is signed off properly, so you have the paperwork when you come to sell.

Get an honest opinion — free of charge

Every house is different, and the right answer depends on your space, your budget and how you live. If you’re weighing up a garage conversion against an extension anywhere in Burntwood, Cannock, Lichfield, Walsall or the wider West Midlands, we’re happy to take a look and give you a straight answer — even if that answer is “don’t bother yet”.

Get in touch with DJF Building for a free, no-obligation quote and consultation. No hard sell, no hidden costs — just honest advice from a local family firm.