Garden Room Cost Guide + Options

If you’re comparing garden rooms and wondering how far your budget can go, this guide is for you. Whether you’re after an outdoor office, gym, or relaxing retreat, here’s a detailed look at what affects the cost.

Garden Room Prices

Here are all the things which can affect the cost of your garden room:

How big it is
What materials it is made of
Whether you add extra insulation features or uPVC
Whether you need to install electricity or plumbing
The cost of extras and furnishings
Whether you have it built for you or do it yourself
Any extra services offered by bespoke providers

Average Garden Room Costs in the UK

Garden room prices vary depending on the size, build, and finish. Here’s a rough guide to what you can expect:

Type	Average Cost Range
Small garden room (2.5m x 2.5m – 3.5m x 2.5m)	£1,000 – £3,000
Medium garden room (4m x 3m – 5m x 4m)	£3,000 – £8,000
Large or insulated room (6m+ or premium models)	£8,000 – £13,500+

Your final price depends on features like:

Wall thickness
Insulation
Glazing
Upgrades such as pressure treatment or uPVC windows

Garden Room Prices by Size

The smallest options go smaller than 3.5m x 2.5m garden offices (approx. 10ft x 8ft). Some are available as small as 2.5 × 2.5m. Prices start from roughly £1,000.

Outdoor rooms of this size are suitable for use as a single-person office or as a sitting room for a small group. At a push, it might make a decent workout space which fits a treadmill. Though there might not be much room to lie and spread out.

At the larger end, you can go to 5m x 4m garden offices and larger. There are some huge garden rooms on the market, some of which reach the point of being close to the size of houses. At the top end, these can exceed £30,000.

But the options from Garden Buildings Direct do not come anywhere near that price point. Our largest garden room is the BillyOh Fraya Max. It can go up to 32 square metres (8x4m) at an RRP of £10,769 (before customisations).

Some companies might offer lower prices. But beware: those rooms might not be very warm if they are made of thin materials!

Garden Room Prices by Materials

Material choice makes a big difference to both cost and comfort. Here’s how the main types compare:

Wooden garden rooms

Wood remains the most popular material for garden buildings. It’s naturally insulating, affordable, and versatile. Prices depend on timber thickness, which affects both warmth and durability:

Wall Thickness	Typical Use	Price Range
19mm	Entry-level summer use	£1,000–£2,000
28mm	Better heat retention	£2,000–£4,000
44mm	All-year comfort	+£600–£800 (upgrade cost)

Upgrading to a 19mm roof and floor adds £100 to £300 each. For gym use or heavier furniture, thicker flooring is essential. Thinner 11mm boards won’t handle impact or weight for long.

Metal garden rooms

Metal garden rooms stand out for their modern look. They suit contemporary gardens best but need insulation for year-round use. Without it, the space can get too cold in winter and too hot in summer.

As a result, and due to the higher cost of materials, they typically start at around £6,000 for basic models. Once you add insulation, metal garden rooms tend to fall into the higher price bracket.

Insulated garden rooms

For the best all-round comfort, insulated garden rooms take things up a notch. These include insulation panels built into the walls, floor, and roof. Plus, double glazing as standard.

Our BillyOh Outpost Insulated Garden Room starts around £3,800 RRP. Large, premium models can reach £13,500. You’ll pay more upfront, but you’ll also save on energy costs and enjoy a usable space all season.

Summary cost by material

Material	Starting Price	Best For	Notes
Wood	£1,000+	Everyday use	Naturally insulating
Metal	£6,000+	Modern styles	Needs added insulation
Insulated (Wood)	£3,800+	All-season comfort	Includes double glazing

Taking the DIY route? Here’s how to insulate a garden office.

Pressure Treated Garden Rooms

And then there’s pressure treatment. This comes down to how much you are willing to work on maintaining your wooden building. Pressure treated wood has preserver soaked deep into its fibres. This process protects the material against rot and moisture for a very long time. Wooden garden rooms treated this way also come with a longer guarantee.

Cost of pressure treatment

The price varies with size and build type:

Building Size	Typical Upgrade Cost
Small log cabins	From £300
Large garden rooms	Up to £3,000

It’s true that it adds to the upfront cost. But that also saves you hundreds in maintenance and extend your building’s lifespan by years.

To see how it works and why it matters, read this: What Is Pressure Treatment and How Does It Protect Wood

Garden Offices with uPVC Double Glazing

Upgrading to uPVC double glazing is one of the best ways to boost comfort and security.

Better insulation and security

uPVC window and door frames seal tightly and prevent heat loss. The multi-point locking systems are a major upgrade from the locks used on timber windows. This feature is ideal for offices, gaming rooms, or studios where you’re storing valuable tech.

Easy maintenance

uPVC frames are built to last and require less upkeep than wood. If condensation ever forms between glass panes, the repair is simpler and less costly.

Cost and options

The price of uPVC upgrades depends on how many windows your building has and their size:

Building Feature	Estimated Cost Range
Small garden room upgrade	Around £1,500
Larger or multi-window builds	Up to £4,000

Note: uPVC frames are only available on 44mm-thick walls or higher. Pricing can vary based on colour or finish.

Prefab Garden Room or Bespoke – Which Is Better for You?

Bespoke garden rooms give you full creative freedom. You’ll work with designers who tailor every feature to your space and preferences. However, this level of customisation often means:

Property surveys before quoting a price
Longer waiting times to get an estimate and delivery
Extra labour costs, which increase the total price

Bespoke projects suit homeowners with very specific design needs or unique site conditions. But for most buyers, this path can take more time and budget than expected.

In contrast, prefab garden room kits are a straightforward alternative. You can:

Choose your preferred size and add-ons online
See the total price instantly
Order, prepare your base, and start building

It’s a quick, transparent process with no hidden fees. This is perfect if you want to enjoy your garden retreat sooner rather than later.

Insulation options and costs

Installation can add between £600 and £2,000, depending on size and provider. Bespoke companies often include or offer this as an add-on, while prefab kits keep it optional. That said, a wooden prefab garden room can be built over a weekend with basic tools and one extra pair of hands.

If you want a modern and sturdy space built fast, prefab garden rooms are a smart choice. You’ll still have customisation options, but at a faster pace and lower cost.

Garden Room Price Breakdown

Before choosing your garden room, see where your budget goes. Here’s a look at the average costs based on Garden Buildings Direct prices:

Feature or Upgrade	Typical Price Range	Notes
Basic building (log cabin)	£1,000 – £11,000	Depends on size and wall thickness
Basic building (insulated)	£3,100 – £10,000	For year-round use
Timber thickness upgrade	£300 – £700	For smaller log cabins only
Pressure treatment	£300 – £3,000	Adds long-term rot protection
Floor and roof upgrades	£100 – £600	Improves comfort and durability
Double glazing or uPVC doors/windows	£200 – £4,000	Available on 44mm+ wall thickness
Electricity and plumbing	£500 – £3,250	Installed by licensed professionals

Budget tip: Start with the essentials, like insulation and pressure treatment. You can always add extras such as uPVC windows or electrics later to fit your budget.

Ready to Plan Your Build?

Now that you’ve got an idea of what affects pricing, it’s time to start planning what yours could look like.

Take Sophie’s Customer Story, for instance. She decided to branch out and test herself by creating an external workspace. And she found our BillyOh Fraya and now enjoys working from her garden.

‘Work in peace! It’s so enjoyable feeling like you’re outside with the comforts and set up of a real office inside.’

You can do the same, but you have to find the right one for you first. Browse here: Garden Room Buying Guide

Shop Garden Rooms

FAQ

Are these prices fixed?

No, prices can vary depending on size, upgrades, and current offers. Always check the latest deals before ordering.

Can I install electricity and insulation myself?

Basic insulation can be done DIY. But all electrical work must be handled by a licensed professional for compliance. Learn more: How to Run Electricity to a Garden Room

Do garden rooms add value to a property?

Yes, when they are well built, insulated, and maintained. Many UK property experts estimate that a quality garden room can increase a home’s value by about 5% to 15%.