Bedding plants

Building the greenhouse foundation - Instructions and notes


When building a greenhouse, the right foundation is the basis. It not only ensures a secure footing, it also protects against frost.

© Sonja Birkelbach -

The greenhouse should remain in the garden all year round and not only absorb plants, but also defy wind and weather? Then a solid construction is the prerequisite for this. The hobby gardener creates the basis for this with a solid foundation. We will tell you below why the foundation is so important for greenhouses and what possibilities there are to create a foundation yourself.

Why are foundations so important?

This question can be answered in one sentence: A foundation prevents your new greenhouse from collapsing like a house of cards in strong winds and storms. With the foundation you create a load-bearing substructure, which ensures the stability of the greenhouse in all weather conditions. The foundation has many functions. The construction must be able to withstand its own load and the weight of the greenhouse on it. It must not happen that the foundation drills further into the ground because the pressure exerted on the foundation is simply too great.

Tip: A foundation also protects against the fact that heat is unnecessarily lost through the ground and the temperature can be maintained in the greenhouse.

Does every greenhouse need a foundation?

Solid greenhouse structures always need a foundation. A foundation can only be dispensed with if it is a small greenhouse made of foil that is only set up during the summer. So that the greenhouse still stands securely and does not lift during the first gust of wind, it is important to securely fasten the pipes, over which the film is usually stretched, with ground anchors in the ground. Simple small greenhouses can also be weighted with bricks or the like, or you can tie the pipes to fences or walls.

Different foundations

First of all, it is important to distinguish whether you choose a prefabricated set from a specialist dealer or whether you want to build your small greenhouse yourself. Finished sets are usually supplied with a suitable frame made of wood or metal, which takes on the function of a foundation. When assembling on site, you should follow the instructions included and attach great importance to statics and safety.

If you want to build your own greenhouse, you can choose between different foundations:

  • Beamed foundation
  • Metal tube frame with ground anchors
  • Pour the floor area with concrete
  • Strip foundation made of concrete
  • point foundation

Which foundation should I choose?

© dmitrypk -

Of course, this is up to you. Point foundations are mostly used in the construction of greenhouses. Metal foundations are usually too expensive to build greenhouses. You also have the option of partially building the foundation out of wood. This will be discussed in more detail below.

The foundation should ensure that your new greenhouse stands securely and that storms and rain cannot harm it. The size and weight of the greenhouse are important criteria for choosing the right foundation. The planned use also plays a role.

Tip: Larger greenhouses often require a building permit.

The foundation of the foundation forms the solid basis for the future greenhouse. Therefore, work carefully and adhere to the respective dimensions. The foundation must appear straight and rectangular. Also make sure that the surface is horizontal and smooth.

Lay the foundation yourself

A solid foundation can be created by bricking a strip foundation or pouring the foundation using fabric mats and formwork boards. First you have to dig a trench. This ditch should be one Depth of at least 80 cm own so that the frost cannot work and the foundation does not rise as a result. After you have concreted or bricked the foundation, fill the recess with earth and attach the foundation frame.

What dimensions does my foundation need?

The dimensions of the foundation will certainly vary. No compromise should be made on depth. We have already spoken of a minimum depth of 80 cm. In the low mountain ranges and other regions with less favorable climates, however, the frost can work up to 1.5 meters into the ground and cause damage accordingly.

Tip: A foundation depth of just over one meter is a good alternative for all climatic conditions in our latitudes.

The dimensions of the foundation will ultimately depend on the size of the greenhouse. The weight of your new greenhouse determines the strength of the foundation.

Why does a foundation need a layer of gravel?

A gravel layer under the actual foundation offers you additional security. The ballast should reach a depth of at least ten centimeters. For slab foundations, the same thickness can be selected as for the foundation itself. The water can drain better through the gravel layer. This is particularly useful if you have floors that are difficult for liquids to drain. Very few plants tolerate waterlogging and waterlogging is tolerated here.

What is important when laying a concrete foundation?

measurementThe exact measurement of the foundation is decisive for the later status of the greenhouse. The best thing to do is to prepare a batter board and pin out the corresponding area.
Dig the trenchThe trench must have a depth of at least 80 cm. In areas with a harsher climate, depths of 1.20 meters are advisable. Digging is important so that no moisture can get into the greenhouse material and endanger its stability.
Insert concrete pipesIf a point foundation is to accommodate posts and supports, concrete pipes are let into the ground. Here, too, measurements must be carried out precisely. Use a spirit level before filling the concrete into the pipes.
Pour concrete foundationConcrete foundations can be bricked or are poured from concrete slabs. Whether a concrete foundation really offers a stand is often dependent on the dowels and screws that you use for fastening. Larger greenhouses need a concrete strip foundation.

Wooden foundation as an alternative to the concrete foundation

Foundations are commonly made from concrete, but you can also use wood to some extent. The foundation consists of a wooden frame made of squared timber. The frame is also provided with longitudinal and cross struts. The wooden frame is ultimately applied to point foundations.

What is a point foundation?

A point foundation can be used to hold your wooden frame and anchor it securely in the ground. For this, anchor shoes are poured into the foundations. The square timbers of the wooden frame can be attached there later. Point foundations are an inexpensive alternative to the slab foundation. Furthermore, an optimal heat exchange is ensured. The moisture does not build up, but can dry well due to the distance between the grain and the wooden foundation.

Create a point foundation - step by step

  1. Dig holes
  2. Apply the foundation frame
  3. Fill holes with concrete
  4. Align the foundation frame exactly