What Are The Best Footings For a Garden Room

OllieMaterials Used

Ground Screw installation

Footings – Understanding Your Options

The benefit of a garden room as opposed to an extension, is that there are various ways to construct the base. An extension is nearly always on a strip foundation or concrete raft, involving lots of digging and plenty of concrete.

As the world is becoming more aware of sustainability and carbon footprint, it’s important to recognise that concrete is one of the worst offenders. Concrete is said to be responsible for 4-8% of the world’s CO2.

We recognise this and have explored the various options for alternative solutions. Mindful that our garden rooms are fairly substantial (weighing in around 2-3 tonnes), we are also acutely aware that any foundation must be structurally sound.

Following on is a list of some of the options we offer here at Outdoor Modular Spaces.

Ground Screws

Although these have been around for many, many years, they are becoming more commonly known as they are favoured by many in the garden room industry. Thanks to their incredible strength, ground screws or screw piles as they are often referred to, are capable of carrying the same load as a concrete foundation. Made from a galvanised steel pipe, they are driven into the ground using a high torque ground screw-driver.

The benefits of using ground screws are:

  • Tried & tested system
  • No / minimal displacement of soil
  • Environmentally friendly
  • Barely any damage to surrounding areas (trees, hedges, etc.)
  • High load-bearing capacity
  • Recyclable
  • Immediately loadable
  • Overcomes sloped areas

Concrete Plinths

What Are The Best Footings For a Garden Room Oudoor Modular Spaces

Concrete? Yes, concrete plinths are more environmentally friendly than concrete rafts. Here’s why.

As these are pre-cast concrete, the manufacturing process has been completed off-site in a controlled environment, without the added environmental impact of separate materials being transported to site.

Concrete plinths are relatively light weight but incredibly strong – with a load-capacity of up to 5 tonne per plinth.

The benefits of using pre-cast concrete plinths are:

  • 100% Recyclable
  • Easy to position and reusable
  • Environmentally friendly
  • High-load bearing capacity
  • Heavy gauge steel brackets

Plastic Plinths – JackPads

What Are The Best Footings For a Garden Room Oudoor Modular Spaces

Don’t be fooled by the description! These support blocks may be made from recycled plastic but are strong enough to support single, double and treble storey modular buildings! This is a tried and tested solution that’s been around for over 17 years. It’s also approved for use by Building Control.

Due to the very nature of the product they can be re-used, recycled and assist in achieving sustainability targets. With a fully adjustable steel bracket, they work in most environments, regardless of a slope or not.

As with the ground screws and concrete plinths, this type of footing allows us to build on the same day – no waiting for concrete to cure.

The benefits of using plastic plinths are:

  • Environmentally friendly – 100% sustainable, 100% recycled materials, 100% recyclable, 100% reusable
  • Quick and easy to install
  • No ground preparation required
  • Very high-load capacity (up to 385kN)
  • Works with all size buildings
  • Overcomes sloped areas
  • Tried & tested

Checkout this YouTube video of when Carlsberg used the JackPad for an off-grid pub!


In some instances, we have to use a concrete base (commonly referred to as a raft). The benefit of concrete is well known – if constructed correctly, it’s less likely to cause any problems. That being said, the exact specification of the raft depends very much on the size of the garden room, the surrounding area and the soil type. For most builds, we’d include a steel mesh so that any ground movement would not split or crack the raft, sat on a sub-base of aggregate.

The benefits of using plastic plinths are:

  • High-load capacity
  • Tried & tested system
  • Approved by building control
  • Easy to install

There you have it, our various solutions to a garden room base. Each solution is chosen based on the environment where the garden room is being built.


Ready to choose a design? Head to our design page here to view our range of garden rooms.

If you’d like more information on the materials we use, cost or availability, please click on one of the following options: