
When you’re thinking about the foundations for a Garden Room, you need to appreciate that the size, specification and weight of the building have a huge influence over what kind of base you should construct.
If you’re looking for a Garden Room under 12m2 then our new specification is not only more affordable than a custom build, it also needs a level slabbed base or ground screws. Lighter buildings = different bases.
Typically a Blackstone Garden Room will weigh over 2 tonnes. We would normally recommend a concrete plinth built to a specific specification. However, new technologies, such as ground screws, are offering a more eco-friendly alternative.
Let’s have a look at both options…
Concrete Plinth
For years we’ve been involved with specifying a structure for the concrete bases required to support our buildings – most commonly for our Garden Rooms and Garages.
Let’s call it ‘clever-clogs concrete’ – a nice, easy way to remember the importance of the base make-up.

1. Excavation
It can become awfy costly if your planned site has terrible access and is on what some may describe as a cliff face.
The excavation is where the groundsmen dig down to firm ground and level off the site in preparation for the next stage. Every site is different and that is why a ‘ballpark’ figure isn’t always achievable until a site visit is carried out.
2. Hardcore
The bottom of the base needs a solid foundation to withstand the weight and form of the concrete and the building. The Hardcore is levelled out and compacted with a whacker to provide a stable sub-base.
3. DPC
This is the damp proof course which is needed to stop any damp seeping through the concrete floor. It’s really important not to miss this stage because if you have additional moisture in your concrete it can freeze and crack the entire base.
4. Form
Using timber supports, the groundsman will create a form to pour the concrete into. This makes a mould for the concrete to set in.
5. Pour and Finish
Pouring the concrete is usually done by the concrete supplier, to make sure of an even distribution across the full area. The Groundsman can then screed the concrete before finishing by floating it to a smooth neat finish.
This isn’t something we would recommend trying yourself, as the plinth needs to be level and in-square – something that isn’t easy to do ‘off-hand’.
At Gillies & Mackay we recommend the following contractors for our concrete bases.
- CSR Joinery & Landscaping (our sister company and our top nod!)
- Carmichael + Baxter (throughout Scotland)
- Homescape (Perthshire)
- Terrain Ground Care (Central Belt)

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Ground Screws
Ground screws offer an alternative to concrete when you need more flexibility.
The screws are bored into the ground creating a solid, level framework to build the structure’s base on. It is a quick and tidy procedure and less disruptive to the environment than a concrete-based foundation.
Ground Screws Scotland in Edinburgh has been a great addition to our recommended trade. We are headache-free when it comes to bad access sites or impossible excavation. We love working with them.
Gary at Ground Screws Scotland has been able to help our customers get their dream Garden Room without disrupting/upsetting their original landscape or costing an absolute fortune because of labour.
The ground screws are fitted typically within 4 hours.
It’s important to note that ground screws are purely for the foundation of the building. So they will follow the lay of the land, which can mean the head of the screws will be visible. You may wish to add additional landscaping to hide these heads and help the building fit within its surroundings.
In a recent project, ground screws were used to help with a cliff-facing site with restricted coastal access.
The results were perfect…
Preparation is everything and it’s entirely up to you which option you choose when it comes to your Garden Room and existing site.
We won’t leave you on your own with this though. Part of the Garden Room ordering process involves us coming out to see your site and helping you decide what Garden Room base would work best.
We all need a good foundation in life and it’s no different for your Garden Room!
All my #ShedLove
Natty x









