Is It Cheaper to Buy or Build a Garden Room? A Full Cost Comparison

Thinking of adding a garden room but torn between buying or building? Building it is usually cheaper, if you’ve got the skills, time, and tools. But cost isn’t the only factor. Read on to find out what really makes the difference (and what could trip you up).

The Core Question: DIY vs. Professional Installation – An Overview

There’s something undeniably satisfying about building something with your own two hands. But let’s be honest: it’s not always as easy (or as cheap) as it looks on YouTube.

Choosing between DIY and professional installation isn’t just about saving money—it’s about saving time, sanity, and sometimes, the final finish.

Let’s start by pulling apart the biggest assumptions.

The Initial Price Tag: DIY Often Appears Cheaper

The general perception? Building your own garden room saves money because you’re cutting out one major expense: labour.

If you buy materials yourself—or opt for a kit—you avoid the professional markup. Many DIYers find kits for under £10,000, especially if they’re happy with a simple design.

At first glance, that’s a big win for the budget-conscious.

The Reality: Beyond the Initial Cost

But here’s the twist: the “cheapest” route isn’t always the best value.

Hidden costs creep in, like tool hire, mistakes that need fixing, or delays that drag on for months. And your time? That’s worth something too, especially if you’re using holiday days to dig foundations in the rain.

Plus, if anything goes wrong down the line (leaks, drafts, uneven floors), it’s all on you.

Option 1: Buying a Garden Room (Prefabricated, Modular, or Bespoke)

A. Prefabricated / Modular Garden Rooms

These are the ready-to-go options. Think flat-pack, but elevated. Prefab garden rooms are designed off-site, delivered to your home, and either assembled for you or built from a kit.

Some companies offer supply-only kits. Others handle the entire process, from base to electrics.

Average Installed Cost: £8,000 – £30,000+

What’s Included: Structural materials, insulation, double glazing, electrics (often), doors/windows

Additional Costs: Delivery (sometimes), custom upgrades

Pros:
Fast build times (often completed in days), reliable quality, warranties, and fewer surprises. It’s plug-and-play luxury.

Cons:
You’re limited to pre-designed layouts unless you spend more for custom tweaks.

B. Bespoke / Custom-Built Garden Rooms

Want a garden room that perfectly mirrors your Pinterest board? This is the gold-standard route.

Bespoke builds are tailored to your vision and made on-site by professionals. Everything from the architecture to the electrical layout is designed to your brief.

Average Cost: £20,000 – £60,000+

What’s Included: Design services, high-end materials, skilled labour, complex foundations

Pros:
Total freedom. Higher build quality. Better integration with your garden. And usually managed by someone who’s done this a hundred times before.

Cons:
It’s the priciest option—and the slowest. But for those wanting a long-lasting, premium space, it’s worth every pound.

Option 2: Building a Garden Room Yourself (DIY from Scratch or Kit Assembly)

A. DIY from Scratch

This is the full self-build experience. You buy the timber, dig the footings, and do every last bit yourself—from insulation to paint.

It’s not for the faint-hearted, but the cost savings can be significant.

Materials Only Cost: £4,000 – £15,000+

What You’ll Need:
Foundations: £500 – £3,000+
Cladding: £50 – £150+/m²
Roofing: £50 – £100+/m²
Windows & Doors: £500 – £2,000+ each
Electrics (inc. pro install): £500 – £1,500+
Finishes: Flooring, plaster, paint
Tools: Either owned, rented, or bought

Pros:
Maximum savings and control. Great if you already own tools and know your way around a saw.

Cons:
Takes serious time and skill. Errors can be expensive, and there’s no safety net. The quality can vary wildly depending on experience.

B. DIY Kit Assembly (Self-Build Kits)

Prefer a middle ground? Self-build kits are pre-cut garden room packs you assemble like giant Meccano sets.

They come with instructions and include most of what you need—minus foundations, electrics, and internal finishes.

Kit Price Range: £3,000 – £15,000+

Extras Not Always Included:

Foundations

Electrical setup

Interior finishing

Tools for assembly

Pros:
Less overwhelming than starting from scratch. Faster, with decent instructions. Some kits even allow minor layout changes.

Cons:
Still physically demanding. Limited in design. And you’ll need a professional electrician to finish the job safely and legally.

Hidden Costs and Considerations for Both Options

1. Ground Preparation & Foundations

One of the most overlooked expenses. If your garden’s sloped, marshy, or uneven, prepping the base can cost more than you think—sometimes thousands.

2. Electrical Connection

Even in a DIY build, you’ll need a certified electrician. Costs rise if your garden room is far from the house or needs serious power.

3. Plumbing (If Required)

Adding a loo or sink? Get ready for extra cost and complexity—think trench digging, waste pipes, and possibly a macerator.

4. Planning Permission & Building Regulations

Most garden rooms fall under permitted development, but not all. Taller rooms, sleep-in spaces, or listed properties may need planning—and that adds fees and red tape.

5. Delivery Costs

If you’re buying a large kit or prefab unit, especially for rural or tight-access sites, delivery isn’t always free.

6. Interior Fit-Out & Furnishings

From stylish flooring to light fixtures and furniture—none of this is usually included. And it adds up fast.

7. Landscaping

Don’t forget the finishing touches—decking, pathways, and plants to blend the structure into your garden.

8. Time & Effort (The "DIY" Cost)

Ask yourself: what’s your time worth? DIY can eat weekends and evenings for months. A pro install gets you over the finish line much faster.

Making the Right Decision: Build vs. Buy

When "Building" (DIY/Kit) is Likely Cheaper and Suitable:

You're on a tight budget and every penny counts.

You’re comfortable with carpentry, electrics, or managing trades.

You enjoy hands-on projects and don’t mind problem-solving.

You’ve got time and flexibility to take it slow.

When "Buying" (Installed Prefab/Bespoke) is Often Better Value:

You want it done fast, with minimal hassle.

Quality and durability are non-negotiable.

You want a polished space with plumbing, insulation, or heating.

You’re focused on increasing property value with a top-tier finish.

You want warranties, support, and zero surprises.

Conclusion: Beyond the Initial Price Tag

Reiterate the Trade-Offs: Cost vs. Time, Skill, Quality, and Convenience

Yes, DIY can save money. But if your evenings are already packed and you’re new to building, that saving might come at a cost—your time, your sanity, and possibly your safety.

Buying offers peace of mind, speed, and professional polish—but at a higher price.

Advise on Thorough Budgeting for ALL Potential Costs

Don’t just compare kit vs. install prices. Include everything—from foundations to finishings. That’s the only way to avoid nasty surprises halfway through your build.

Your Ideal Garden Room: The One That Best Balances Your Budget, Skills, and Desired Outcome

Whether you buy or build, your garden room should fit your life—not the other way around. Think beyond cost: consider how you’ll use it, what you’re comfortable taking on, and how much effort you’re really ready for.

Ready to Build Your Dream Garden Room Gym?

Looking to transform your garden room into a stylish home gym or spa sanctuary? We offer a fully bespoke service — connecting you with top-rated garden room suppliers and premium fitness equipment brands to create a space that’s uniquely yours.

Call us on 0330 0430 089 or email support@totalgymstore.co.uk to start your personalised garden gym journey today.