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You’re ready. It’s time. You’ve been putting up with a cramped living space for too long and you need more. Never mind your small and medium-sized Garden Rooms. You are ready to go all out. You are ready to go BIG with your Garden Room dreams.

Whether it’s a photography studio, a place to put the mother in law when she comes to stay, or a retirement oasis, our large Garden Room offers a roomy solution, complete with light, power and heating for the perfect garden escape.

So, let’s get into it, shall we? How much is a large Garden Room from Gillies and MacKay going to cost you?

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How much does it cost to install a Garden Room?

Your Garden Room is a big deal. And they don’t come cheap. So making sure you budget for your Garden Room is important. It’s tough to give you an exact cost, as it will depend heavily on size. And also on a number of other factors.

But that doesn’t mean we can’t give you an idea to help you figure out how much money you are talking about.

Out full range of Blackstone Garden Rooms cost between £13,000 and £40,000 on average.

Let’s look into that a little more to help you figure out how much it will cost to install a Garden Room on the larger side.

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How much does it cost to install a Large Garden Room?

Right to the limits: Large Garden Room UNDER 30m2

That’s it. You’ve had enough. You need more space. And you need as much of it as possible.

But you’re no fool. You’ve already read our blog on planning and building control and you know building control is not for you. That’s why you’ll be pushing your Garden Room ‘right to the limits’. No plumbing, within 30m2 and best of all, no building control required. Ya beauty!

One of the beauties that we pushed ‘right to the limits’ was Mr & Mrs Barley’s Garden Room. A beautiful, tranquil room, perfect for retirement and all within permitted development.

The Barley comprises of 2 sets of french doors, 4 sidelights, 2 casements, veranda/canopy, and a wood-burning stove.

photo of the barley

This is how much something like this would cost:

External building size: 6m x 5m
Full body = £25,078.00
Steel box profile roofing: £1,800.00
Fitting and finishing = £2,568.00
French doors (x2) = £4,000.00
Sidelights (x4) = £3,200.00
Opening casement window x2 = £1,300.00
Veranda canopy 1.2m = £2,300.00
Laminate flooring = £2,850.00
Guttering = £650.00
Total = £44,376.00

Upgrade to Larch cladding = £POA

Looking for something a little different? No worries. Every single one is custom built so we can do whatever you want and this will change the overall cost. But this will give you an idea of how much a big Garden Room will cost.

The fue shebang: Large Garden Room OVER 30m2

Fancy going all-out?

If you are ready to take on building control because you definitely want the building to be over 30m2, or you need washroom facilities hooked up to the mains water supply, then you’ll want to go all out and get ‘the fue shebang’. Holiday home. Granny flat. Retirement cottage. The possibilities are endless.

The Spindrift is a cracking example of how you can construct a 2-bedroom holiday home within 60m2.

drawing of plans for outer of spindrift garden room
Spindrift 10m x 6m [2-Bed Open Plan Lodge]

The Spindrift comprises of 1 set of french doors, 2 sidelights, 5 casements, porch, bathroom, kitchenette and 2 bedrooms.

With something of this size, you will not only need to consider the cost of the building but also the building warrant, which will involve architects, engineers, and applications. This can add a considerable amount to the cost.

On average, a Garden Room over 30m2 that requires a building warrant will be in the region of £60,000 to £90,000 all-in.

There are also some additional factors to consider below that will affect the cost of your Garden Room (whichever size you choose), which include:

  • Planning permission/building control
  • Groundworks preparation
  • Electrical installation

Related content:

How much will planning permission or building control for a Garden Room cost?

By pushing ‘right to the limits’ with a Garden Room that is under 30m2, you can usually avoid having to get a building warrant, assuming you don’t tap into the mains water supply.

This is one of the main reasons people try to keep the Garden Room building under 30m2, as you won’t need an architect, engineer or building warrant so it keeps the overall construction costs down.

Even though you probably won’t need a building warrant, you may still need planning permission.

You won’t need planning permission as long as you comply with the following:

  • your Garden Room is located at the back of the house,
  • it is not used as a separate home to live in,
  • the Garden Room and any other development, does not take up half or more of the ‘curtilage’ (this means half or more of the grounds behind your home),
  • it is not higher than 4 metres at the highest point,
  • any part of the Garden Room that’s a metre or less from the boundary is no higher than 2.5 metres,
  • the eaves (the part where the wall meets the roof) are no higher than 3 metres,
  • if the land is in a conservation area or in the grounds of a listed building, the Garden Room has a footprint of less than 4 square metres.

You can read the full article here: Garden Rooms: Do I need Planning Permission and/or Building Control.

Assuming you comply with ALL of the above. And assuming you don’t need a building warrant, then you are good to go and install your Garden Room.

Great news.

If you don’t comply with all of the above then no need to worry. Planning applications are pretty straightforward and not too much of an additional cost.

You’ll need scale drawings of the Garden Room and the site plan to show where you are putting the building in relation to your house and the rest of your garden.

How much will this cost?

If you want us to take care of all the planning and submit the applications as well as elevation drawings then we can do all of this for £650.

Otherwise, you can get standard elevation drawings for around £240. And submit your own planning application for £202.

If you go for ‘the fue shebang’ you WILL need a building warrant. This will involve architects, engineers and planning. And so will add a substantial amount onto the building costs. This will need to be costed and factored into the overall Garden Room budget.

How much does ground preparation for a Garden Room cost?

A bigger Garden Room means they are going to weigh more. So making sure the foundations are done good and proper is even more important. As with all our Garden Rooms, we don’t dabble in the groundworks. We leave that to the tradies who are skilled in that area. We can recommend professionals that we’ve worked with before to get you sorted.

Because we don’t get involved in them, the groundworks are an additional cost on top of the above prices. So how much can you expect to pay for the groundworks for a large Garden Room?

As with both small and medium Garden Rooms, the most important consideration with groundworks is that the price is completely dependent on the existing ground level and access conditions as both these factors will affect the labour required. So it’s pretty difficult to give a ballpark figure when it comes to groundwork until the site has been accessed.

For a building that ‘right to the limits’ (eg. under 30m2), there are two options for preparing the ground for a Garden Room: a concrete plinth or ground screws.

A concrete plinth is the traditional and most common base for a large Garden Room. This will typically cost you around £3000 to £6000 for a small to medium-sized Garden Room, depending on the access and ground conditions.

Ground screws are a much less damaging to the environment than a concrete base and are usually around £2000 – £3,000 for a large Garden Room, again, dependent on access and level conditions.

If you choose to go even bigger and go for ‘the fue shebang’ then your groundworks will be little different (and more expensive) as you’ll need to go through building control, who are concerned with the structure and safety of your building.

Related content:

How much will electrics for my Garden Room cost me?

What’s a Garden Room without a little bit of power? An electrical supply allows you to install light and power so you can turn your Garden Room into the oasis of productivity that you want it to be.

We’ll hook you up with our recommended supplier, Robert Clark Electrical Contractor – no problem. They are used to working with our buildings so ken what they are doing.

The cost of electrical installation for a large Garden Room will depend on the distance of the Garden Room from the main electrical box in your home. And it will depend on the electrical specifications you are looking for. A standard cost for electrics within a large Garden Room will be around £1800.

In conclusion

Want to make sure you get the most out of your space while keeping it within permitted development?

We recommend you push your Garden Room ‘right to the limits’. A large Garden Room (up to 30m2) with endless opportunity and room for activities, whatever they may be, without the expense and hassle of going through building control.

It really is the best of both worlds.

But, if you are ready to go all out (and what the heck, you aren’t scared of building control, this is your dream #ShedLife we are talking about)?

Well then, in that case, you may as well go all-in and go for ‘the fue shebang’. It’ll be more expensive, a little more time consuming with some more paperwork and a few more people involved. But when you’re sitting in your new build relaxing, will any of it really matter? Probably not. 

So what are you waiting for? 

You know where to find me.

Natty x

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