Garden shed foundation tips

For Biohort Garden Sheds, Equipment Lockers and the MiniGarage

A level foundation is essential for the successful assembly of our products. The garden shed is anchored to this foundation to withstand stormy weather using the fastening material supplied.

Points to note about the foundation    Use of existing foundations


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What is the best foundation solution for your product? Our Foundation Finder will help you find out. In just a few steps, it will tell you which foundation you need. The outcome for you: a clear recommendation and suitable alternatives!


There are many options for installing a suitable foundation:

Biohort SmartBase & SmartBasePLUS
The foundation solutions specially developed by Biohort are ideal for all Biohort Garden Sheds, the Equipment Locker and the MiniGarage.


More about SmartBase foundations

Concrete foundation
Concrete foundations with or without graduation are a high-quality foundation option for our Biohort


More about the concrete foundation

Point foundation with the aluminium floor frame
A point foundation can be erected with the aluminium floor frame - even on uneven and soft ground.


More about the point foundation

Concrete slabs on a gravel base are a good, reasonably priced solution. These slabs are available in various finishes and colours from all builders' merchants.


More about the gravel base foundation

Assembling the garden shed on a Biohort floor frame and anchoring it into the ground with the anchors supplied is the easiest installation option.


More about installing with the aluminium floor frame

For our Biohort CasaNova® Outbuilding 
we have put together a few of our own foundation tips.


Go to the Casanova foundation tips

Points to note for the foundation

A level foundation is essential for the successful assembly of our products. The garden shed is anchored to this foundation (or with the floor frame available as an accessory) to withstand stormy weather using the fastening material supplied.

Ground conditions

A solid surface should be used, if possible. The SmartBasePLUS requires established, well-compacted soil.

Foundation alignment and size

The foundation must be level so that the garden shed can be installed properly. If the product is on a slope, functionality may be limited (for example, the doors cannot be adjusted correctly) or the screw holes are not correctly aligned (holes do not line up). The foundation dimensions must be followed - please refer to the foundation plans

Vapour barrier

Plastic membrane with a minimum thickness of 150 μm = 0.15 mm

Ideally incorporate the membrane in the foundation. This is to prevent moisture from rising from the ground into the interior of the garden shed. Ensure that the membrane is not bigger than the surface area of the garden shed. This is because rainwater should be able to trickle into the ground sideways.

Sealing joint

The contact surface between the foundation and the aluminium floor frame should be sealed to prevent rainwater from entering the garden shed. The sealing is recommended in particular when using the aluminium floor frame.

A sealing compound is used as the sealant (suitable for outdoor use and metal). To ensure optimum sealing, the sealing joint should be applied beneath the floor frame. Please take into account that due to the nature of the ground (open-pore concrete slabs, joints, etc.), complete sealing is not possible.

Use of existing foundations

Existing surfaces can also be used as a base for Biohort products. If the existing surface is not ideal, proceed as follows:

The existing surface is not level

Recommended solution 1: Assemble the SmartBase

With the help of the SmartBase as a base, slight slopes can be compensated. It includes high adjustable feet that allow compensation of up to 4 cm.

Recommended solution 2: Assemble the aluminium floor frame

Regardless of whether the surface is concrete or paved, you can put spacers underneath to level the floor frame. However, these spacers leave a gap under the frame, which allows water to penetrate or makes it more difficult to seal the garden shed. The spacers should, for example, be made from plastic or rust-proof metal such as stainless steel.

No vapour barrier was laid

Recommended solution: Subsequent installation of the vapour barrier using the aluminium floor frame

You can retrofit the vapour barrier by placing the membrane on the existing foundation inside the shed. The ends of the membrane are pulled up along the inside of the floor frame and the membrane is folded inwards by at least 10 cm. The folded section should also be glued. For a walk-on interior floor, our aluminium floor panel (lined with XPS panels) or any floor can be installed inside the shed.

Use of stones that were too small/too light

Recommended solution: Weighting down of the ground mounting brackets of the floor frame

With a slab stone foundation, the internal floor mounting brackets (Z brackets) attached when using a floor frame can be weighted down with additional weight to increase storm safety.

Note: These foundation tips are non-binding suggestions. The customer is personally responsible for choosing an appropriate foundation design. Biohort cannot accept any liability for damage caused by insufficiently secured products.