Garden Room Cost Guide | Calculate the Cost of your Outdoor Office

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If you’re exploring options for buying a garden room, perhaps as an outdoor office, here is the definitive breakdown of how much you can expect this to cost overall.

Of course, the price range for a garden room can be wide, as it depends on exactly what you plan to build. Not all garden rooms are equal, after all. But in this guide, our garden room experts will explore the full breadth of options so you can gauge where you will fall on the pricing scale.

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

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

At this size, you can expect to pay from around £1,000, depending on what offers are available at the time. Some companies might offer lower prices, but beware: those rooms might not be very warm if they are made of thin materials.

BillyOh Canvas Insulated Garden Room in 3.0×2.5m

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, which can go up to 32 square metres (8x4m) at an RRP of £10,769 (before customisations).

BillyOh Fraya Max in 8m x 4m

So with prices ranging from £1,000 to over £10,000 based on size, the next thing to consider when pricing up your garden room is the materials.

Garden room prices by materials

There are some metal garden rooms on the market. While these are stylish, presenting a near-futuristic look that will fit well into contemporary gardens, they are highly reliant upon extra insulation, as metal alone would lead to the room being very cold in the winter and roasting hot in the summer. The higher cost of metal, combined with the cost of insulation, means that metal garden rooms cost upwards of £6,000 for the most basic options.

On the other hand, wooden garden rooms make use of the naturally insulating qualities of wooden timber. The thicker the timber, the better the insulation, which is why many garden rooms have the construction style of log cabins.

Of course, thicker timber also means a higher cost. While there are options starting from 19mm thickness of walls (at around £1,000-£2,000), this will offer the least protection against the cold. 28mm and 44mm each offer incrementally more thermal comfort. If 44mm timber is an upgrade option rather than included by default, you can expect it to add between £600 and £800 to the price of your building. However, the largest log cabins typically come with 44mm cladding by default.

Roof and floor thickness are also a major consideration. A thin roof will let large amounts of rising heat pass through it, leaving you with a colder room. If you are looking for a room that will be comfortable to sit in all year round, you should ensure that your building has at least a 19mm thick roof and floor, which are often listed as optional upgrades. As separate options, upgrading to a 19mm roof will typically cost between £100 and £300, and the same for the 19mm floor.

If it’s a garden gym you’re after, a thicker floor is an absolute must! If you’re lifting weights or jumping, you would risk causing serious damage on thin 11mm floorboards. Thinner floors are suited to lightweight casual uses only.

For those not content to rely upon the timber alone for insulation, there are garden rooms which come with extra insulation built into the walls, floor and roof. These insulated garden rooms have wall panels which include specialised insulation materials placed in between the inner and outer wooden boards. All pre-insulated buildings should also come with double glazed windows as standard. As the closest thing to a guarantee of year-round comfortable temperatures, insulated buildings are also slightly higher on the cost scale. Our cheapest insulated garden room is the BillyOh Outpost, which starts at around £3,800 RRP (unless there are any special offers on at the time). But they can go up to £13,500 depending on building size and the calibre of the materials.

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, protecting it against rot and moisture for a very long time. You will also receive a longer guarantee if you choose this option. For more information, read: What Is Pressure Treatment and How Does It Protect Wood?

Without pressure treatment, you will need to paint your building with a treatment annually. (This doesn’t sound like a lot of work until you have to use some of your precious time off to go and do it!)

Pressure treatment has to be done at the manufacturing stage, before the building is delivered to you. Again, the cost of doing this depends on the building size. To give you an idea, a pressure treated log cabin can start from an upgrade of around £300 for the smallest sizes, and around £3,000 for the largest size.

Garden Offices with uPVC Double Glazing

The addition of uPVC window frames and doors not only upgrades your insulation, but also the security of the building. Wooden doors and windows typically have a simple lock to be screwed into place, but uPVC has locking pins and multiple points around the frame. If you are storing valuable business assets in your garden office, or expensive gadgets in your outdoor gaming room, this level of security will be important to you.

Additionally, if condensation were to become trapped between the double glazing, this is much easier to repair and replace with uPVC frames.

The cost that uPVC adds depends on how many windows the building has, and at what size. But to give you a rough idea, our cheapest option comes in at around £1,500, while our most expensive uPVC upgrade option is around £4,000.

Note also that due to the thickness of uPVC frames, they are only available on buildings with walls that are at least 44mm thick. Also, the cost will vary by colour.

Should I buy a prefab garden room or go bespoke?

There are many providers of bespoke garden rooms on the market. While many of them are excellent designers and will be likely to help people looking for something very specific, there are additional costs incurred by going this route.

Many garden room providers will survey your property as a part of the process, before they can then give you a quote. Not only does this mean it will take longer to find out how much you will be paying, but the extra labour involved in the process will only add to their final price.

Prefabricated garden room kits, especially when bought online, enable you to pick your size, choose from add-on options, and see your price immediately. Then all you need to do is buy it, prepare your building area, and assemble it. This is the simplest and lowest cost buying path.

Another major cost factor is installation. Many providers, especially of bespoke rooms, include installation with the purchase or offer it as an add-on. However, this can add between £600 and £2,000 to the cost. It is, nevertheless, a tempting option for those who do not feel confident in building their own. For those with the ability to use basic DIY tools, a wooden garden room can be assembled in as little as a weekend, with the help of one other person, which is a great way to save a grand or so.