Garden Room Base: Which One Do You Need?

Like all buildings, garden rooms need foundations. And like all foundations, garden room bases come in various modes and forms. The three most common ones are ground screw, poured concrete slab and concrete pad bases.

There are others but we are going to focus on these three. They are the garden room bases you are most likely to choose or be offered by installers. That brings us to the big question- which of these three garden room bases is best for you?

Well, here is our grand plan to help you answer that question. First, we’ll explore each of these garden room bases, discussing their pros and cons. Then, we’ll explain why bases (in general) are crucial to the structural integrity of garden rooms. Then, we’ll share some tips for choosing the right garden room base.

Ground Screw Garden Room Foundation

For this type of garden room base, the installer drives ground screws into the ground. Then they attach timber to those screws to create the frame of the garden room base. The screws are driven mechanically and arranged strategically. The total amount of screws used and their spacing depend on the garden room's size and the soil's condition.

Ground screw bases need a certain level of soil compactness. So, the installer will survey the site before getting to work. They will confirm that the soil is compact enough to hold the ground screws. Loose, sandy or soggy soil isn’t suitable. Neither is rocky soil. This is the biggest problem with ground screw garden room bases. The level of soil compaction must be just right.

There are positives, too. For example, you don’t have to excavate or use concrete to build a ground screw garden room base. Because of this, installation is fast and non-disruptive. Compared to the other two types of garden room bases, ground screw bases leave the vegetation and soil in the area almost untouched. Did we also mention that ground screw garden room bases cost just £1,500 to £3,000?


  • Installation is fast and not labour-intensive
  • Environmentally friendly
  • Suitable for uneven and sloppy surfaces


  • Requires a certain level of soil compactness
  • Requires specialised labour and equipment
  • The surveys could be costly and time-consuming
  • The ground screws might be visible and unsightly unless you find a way to hide them.
Poured Concrete Slab Garden Room Foundation

Poured Concrete Slab Garden Room Foundation

Poured concrete slabs and concrete pad garden bases have been around longer than ground screw bases. Therefore, you might already know about them. Here is how to make a poured concrete slab base. 

The installer excavates the site according to the required dimensions. Then, add a hardcore of bricks, stones and broken concrete. After this, they will install a timber frame. This frame is only temporary, designed to hold the concrete until it sets.

The next step is to mix and pour the concrete and then wait for the concrete to set. This waiting period could take 24 to 48 hours. After the concrete sets, the installer removes the timber frame, leaving behind a solid concrete base for your garden room.

This base must be higher than ground level to offer the maximum protection from erosion and water buildups. You can add damp-proofing and other reinforcement. However, a basic poured concrete slab base is often more than enough to secure any garden room.

A poured concrete base is a permanent structure, unlike ground screw ones. This has both advantages and disadvantages. For example, a poured concrete base is stronger and more secure. 

However, its installation is also much more time-consuming, labour intensive and disruptive. All the vegetation and soil on the site are removed. Even soil and vegetation that are nearby might be affected indirectly. Finally, poured concrete garden room bases are relatively expensive. You need £2,000-£4,000 to install this base for a garden room.


  • Creates a strong, solid base for garden rooms
  • Soil compactness and slopes are not a problem


  • Relatively expensive
  • Labour and time-intensive
  • Disruptive and not environmentally friendly
  • Difficult to remove

Concrete Pad Garden Room Foundation

Concrete pad bases also require excavation but less extensively than their poured concrete counterparts. Your installer will only have to do mild digging. Then, they will lay down the ready-built concrete pads. The pads function together as a unit, spreading the weight of the garden room (and its content) throughout their collective surface area.

The result is an easy-to-install, secure, and stable base for your garden room. The only problem is that concrete pad bases only work on flat, compact soil. They are also more suited for small garden rooms. If the garden room is too big, there could be issues of cracking and shifting.

Concrete pad garden room bases are very affordable. In fact, at £1,300-£2,000, they are the most affordable ones on this list. They are also quicker and easier to install than poured concrete bases. Finally, they are less disruptive and easier to remove (compared to poured concrete).  


  • Cost-effective
  • Environmentally friendly
  • Fast and easy installation
  • Not as disruptive
  • Easy to remove


  • Suitable for sloped and non-compact soil
  • It is not suited for large garden rooms

Why Do You Need a Garden Room Base?

Buildings need foundations to keep them structurally sound and secure. Imagine what would happen if heavy rainfall or storms come and your garden room is not structurally sound and secure. 

Forget about that worst-case scenario. Typical British weather alone will do severe damage. An unsound garden room will rot, deteriorate and age before its time. It would soak up water, leading to damping and wood rot. All this will happen even if there is no heavy rainfall or storm.

At the very least, bases provide solid and flat surfaces for garden rooms to sit on. This will protect the garden room from wrapping, shifting, cracking and other inconveniences of buildings on uneven surfaces. 

That’s why buildings, including garden rooms, need strong, solid foundations. Bases provide structural support, damp proofing, an even surface and more. 

What Type of Base Do I Need for My Garden Room?

As promised, here are the tips that will help you choose the right garden room base. However, before sharing them, we must discuss the importance of listening to expert opinions. You don't have to make this decision alone. Tap into the knowledge and experience of experts around you. 

Start with your garden room supplier. Ask if they offer or can recommend a service that installs bases for garden rooms. Tell them the soil conditions of the site you want to install your garden room. Then, ask them to recommend a garden room base. 

Until you can consult the experts, here are some tips for choosing a base for a garden room. 

The Compactness and Sloppiness of the Site

Ground screw bases need a certain level of soil compactness. So, they are unsuitable for loose, sandy, soggy or rocky soil. On the other hand, concrete pad bases also struggle in loose and uneven soil. Only poured concrete bases are suitable for all soil conditions. 


When it comes to aesthetics, poured concrete and concrete pad bases are the winners. Besides, there are many ways to improve their visual appeal. With ground screw garden bases, the biggest aesthetic problem is that most people don’t like when the screws are in plain view. You can find a way to conceal them.

Installation Cost

Concrete pad garden room bases are the most affordable options on this list. Poured concrete bases are the most expensive.

Ease and Speed of Installation

If you are in a hurry, ground screw bases are perfect. Your garden room base could be ready within a day. However, they do require specialised skills and equipment. Therefore, if ease of installation is your primary priority, concrete pad bases are the ideal choice.

Environmental Friendliness

Ground screw bases are the most environmentally friendly option on this list. Only concrete pad bases come close in this regard.

Strength and Security

Poured concrete slab bases are the strongest and most secure options on this list. However, the others are more than adequate. They also don’t make permanent changes to your garden space permanently. Still, all three will provide a secure base for your garden room.


The most important factors to consider when choosing bases for garden rooms are the site's soil conditions and your budget. Every other concern is secondary. If the soil is ideal and the installation cost is within your budget, there is no need to worry about anything else.

However, as stated earlier, you should still consult experts and listen to their advice. So, speak to someone before finalising your decision. Start with your garden room supplier. Then, find someone who builds garden room bases. Ask for their advice. Then, schedule a visit and survey.

Finally, remember that there are other types of garden room bases aside from the three in this article. So, be open to other alternatives. Concrete and timber bases are not the only options.

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