A small garden shed not only serves functional purposes, but should also fit aesthetically into the overall picture. So that the appearance does not suffer sooner or later and the garden house is damaged, a stable and secure base is of great importance.
What options are there for a garden house foundation?
Slab foundations, point foundations, strip foundations or concrete foundations are suitable for a stable garden house foundation. Alternatives are drive-in sleeves, plastic, wood or metal substructures. Costs vary between 10 and 100 euros per square meter depending on the material and construction method.
Required materials
The material depends on which foundation you choose. To save costs and reduce the amount of work, you can use alternatives. However, thorough planning is crucial when choosing the foundation, because the load capacity varies greatly.
Typical foundations:
- Slab foundation: gravel and fine sand, paving slabs
- Point foundation: formwork, concrete, concrete anchors
- Strip foundation: formwork, concrete, concrete anchors, possibly gravel
- Concrete foundation: Reinforcing steel, formwork boards, concrete, gravel
Alternatives to solid foundations
It is possible to build a foundation without concrete and slabs. You can use prefabricated constructions made of plastic or metal, or you can make the foundation more individual using point-shaped alternatives. With a wooden foundation, you must ensure that the beams must not come into direct contact with the ground.
| Suitability | Advantage | |
|---|---|---|
| Impact sleeves | light to medium garden houses | easy compensation of uneven floors |
| Plastic | Lightweight buildings | easy to use |
| Wood | medium-heavy garden houses | ecological and cost-effective |
| Metal | heavy garden houses | expandable, change of location possible |
Planning
Good planning is the be-all and end-all of every construction
If you use a simple foundation made of impact sleeves or plastic, thorough pre-planning is less important. If you want to build your garden house on a concrete foundation, planning plays an important role. You can create a simple sketch using paper and pens. Things get more professional with a computerized plan that gives you more flexibility.
SketchUp
With this software you can create simple two-dimensional or clear three-dimensional plans. The basic version is free and offers you various planning tools. Here you can build the foundation to scale so that you can identify and correct potential weak points. Such a plan makes sense for a foundation made of paving slabs, which are to be laid precisely and without cutting.
Thorough planning is also important for the foundation. The free basic version of SketchUp is a perfect tool.
Costs
The most durable variants, which are characterized by high stability, are concrete slabs and strip foundations. You should estimate around 30 euros per square meter for the material costs, although the price can vary greatly depending on the source of supply. If you pave a foundation made of stones or paving slabs, you can expect to pay ten to 15 euros per square meter for cheaper options. If you have the foundation built, the costs will be more than 100 euros per square meter.
Calculation example
There are various companies that offer a complete service. At Mein-Gartenshop24 you can get a small garden house from Karibu with a footprint of around 180 x 120 centimeters and a sloping roof including foundation and on-site assembly for around 1,800 euros. The shed is positioned on impact sleeves and can be painted with wood sealant or varnish if desired. Individual wishes are stated directly when booking online.
How do I build a foundation for a garden house?
If you want to build your own garden house, you can also create the necessary foundation yourself. Beforehand, calculate the load that must be supported by the foundation. You can then decide on a variant.
Pavement slabs for sheds
Excavating and filling with gravel and sand is essential for all types of foundations
The simplest solution for a quick foundation is used paving slabs measuring 30 x 30 centimeters. These can absorb surface loads of 90 kilograms per square meter. Since they cannot withstand punctual forces well, paving slabs are only suitable as a base for light tool sheds or small greenhouses.
Instructions for building:
- Dig out the ground to a depth of 20 centimeters
- Fill the area with gravel and compact it
- fill with fine grit or sand
- smooth with squeegee
- Lay out pavement slabs and fill joints with sand
Paving foundation
If you have paving stones left over from sidewalks or driveways, you can also use them as a foundation for your garden shed. The load-bearing capacity is comparable to that of paving slabs. The construction procedure is similar. The foundation can be demarcated by lawn edging stones.
- Roughly mark out the area with pieces of wood
- Dig about 25 deep and ten centimeters wider than the base area
- Compact the soil well with a vibrating plate
- Align cord frame
- Place curbs on concrete and let them harden
- Fill the area with gravel or gravel and straighten it
- spread fine-grained sand
- Laying paving stones with the same joint width
- Compact joints with sand
Point foundations for small to medium-sized garden houses
Small and medium-sized garden houses find stable support on point foundations. The load is distributed across many individual foundations that lie under the load-bearing beams. The difficulty in construction is that all foundation points are at the same height and must be precisely aligned.
To do this, the ground is leveled and the individual points are marked with a wall cord. Holes 80 centimeters deep and 20 centimeters wide are dug at regular intervals. After the concrete has been poured and hardened, the garden house beams are fixed with concrete anchors.
Tip
If the soil is very loose, formwork is required. You can use formwork stones or thick KG pipes for this.
Strip foundation for large garden houses
A strip foundation is a good option for larger, heavier garden sheds
With this variant, the subfloor must be load-bearing. The weight of the garden house is distributed on a 30 centimeter wide concrete strip that runs under the load-bearing walls. The strip foundation can be stabilized with an additional concrete slab. If no concrete slab is used, the area should be filled with gravel or paved.
Make your own strip foundation:
- Mark garden house outlines with stakes
- mark load-bearing walls
- Dig out strips 80 centimeters deep and 30 centimeters wide
- Paneling walls
- Concreting the trench
Background
Why strip foundations have to be so deep
The ground temperature in Central Europe does not fall below freezing point at a depth of 80 centimeters, even in icy winter months. If the foundation strip extends to this depth, the dreaded frost heave is avoided. When water collects under the foundation and freezes, it is lifted under high pressure. Cracks in the foundation and masonry are unavoidable.
Concrete slab foundation
On very sandy or swampy soils near water that do not have a high load-bearing capacity, a solid concrete foundation should be built. To protect against rising damp, the subsurface is covered with a compacted layer of gravel on which a PE film is spread. High point or surface loads are optimally distributed over the entire base plate.
Construction instructions
The area is excavated to a depth of 30 to 40 centimeters, although the pit should be slightly larger than the dimensions of the base plate. This space will be used later for the formwork. Level the soil in the pit and compact it with a vibrator. The edges are lined with sturdy formwork boards (€85.00 on Amazon), which line up exactly with the surface of the concrete slab.
- Fill and compact a 15 centimeter thick layer of gravel or gravel
- Check the surface with a spirit level and smooth if necessary
- Seal with PE film
- Fill concrete five centimeters high
- Lay out structural steel mesh
- fill another ten centimeters with concrete
- lay out the second structural steel mesh
- Fill the formwork completely with concrete and then smooth it out
Tip
The reinforcement mat protects against cracks forming in the concrete. To further increase stability, you should compact the concrete before removing it.
Frequently asked questions
How much does a foundation for a garden house cost?
The costs vary greatly depending on the type of foundation. If you have a company build a foundation, the costs quickly rise to over 100 euros per square meter. It will be cheaper if you take on the construction work yourself. To produce a continuous concrete slab, you can expect to pay around 30 euros per square meter. If you use individual paving slabs as a base that are laid on a bed of sand, the costs will be around ten to 15 euros per square meter.
Is a foundation necessary?
A foundation ensures stability and ensures that the wood does not come into contact with the ground. If the garden house is located directly on the ground, rain, snow and temperature fluctuations can cause long-term damage. The ground moves throughout the year, which can cause walls to warp or cracks to form. A garden house without a foundation is not recommended. It has no base that distributes the loads evenly. The garden house may sink at certain points if the soil has different properties.
Do I need a permit to build a foundation?
In principle, garden houses that are placed freely on the lawn without a foundation do not require a building permit. They may not be higher than 250 centimeters and must not exceed an area of 300 x 400 centimeters or 10 square meters. As soon as the garden house is to be placed on a foundation, you must find out about the applicable regulations from the responsible building authority. The municipalities decide on the need for a building permit and refer to the state building regulations of the respective federal state.
Are there alternatives to the foundation?
A small garden house can also be placed on a simple foundation made of paving stones, provided the subsoil has been removed beforehand and filled with gravel. If the load capacity is not particularly high, you can attach the garden house to a wooden structure that is supported by several point foundations. This means that the wood does not rest on the floor. A quick foundation for the wooden lattice can also be built completely without concrete. You can use square and superficially grooved stones as point foundations, which are fixed with mortar.
