When building a greenhouse, the right foundation is the basis. It not only ensures a secure footing, it also protects against ground frost.
The greenhouse should remain in the garden all year round and not only accommodate plants, but also defy wind and weather? Then a solid construction is the prerequisite for it. The hobby gardener creates the basis for this with a solid foundation. Below we will tell you why the foundation is so important for greenhouses and what options there are for laying 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 bearing on it. It must not happen that the foundation bores further into the ground because the pressure exerted on the foundation is simply too great.
Tip: A foundation also prevents heat from being lost unnecessarily via the ground and from being able to maintain the temperature in the greenhouse.
Does every greenhouse need a foundation?
Massive greenhouse constructions always need a foundation. You can only do without a foundation if you are dealing with small greenhouses made of foil, which are only set up over the summer. So that the greenhouse still has a secure footing and does not lift off with the first gust of wind, it is important to securely fasten the tubes, over which the film is usually stretched, with ground anchors in the ground. Simple small greenhouses can also be weighed down with bricks or similar, or you can tie the tubes to fences or walls.
Different foundations
First of all, you have to decide whether you want to choose a ready-made set from a specialist retailer or whether you want to build your own small greenhouse. Finished sets are usually already made with a suitable frameWood or metal supplied, which takes over the function of a foundation. When setting up on site, you should follow the instructions provided and attach great importance to statics and safety.
If you want to build your own greenhouse, you can choose between different foundations:
- Wood beam foundation
- Metal tube frame with ground anchors
- Pouring the floor area with concrete
- Concrete strip foundation
- Foundation
Which foundation should I choose?
Of course, this is up to you. Point foundations are usually used when constructing greenhouses. Metal foundations are usually too expensive for the construction of greenhouses. You also have the option of building the foundation partially out of wood. This is discussed in more detail below.
The foundation should ensure that your new greenhouse stands securely and that storms and rain cannot harm it. Important criteria for choosing the right foundation are the size and weight of the greenhouse. In addition, the planned use also plays a role.
Tip: Larger greenhouses often require planning permission.
The installation of the foundation forms the solid basis for the later greenhouse. Therefore, work carefully and stick to the respective dimensions. The foundation must appear straight and square. Also make sure the surface is level and smooth.
Create the foundation yourself
A solid foundation can be created by bricking a strip foundation or pouring the foundation using fabric mats and shuttering boards. First you need to dig a trench. This trench should be deep of at least 80 cm 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 cavity with soil and attach the foundation frame.
What are the dimensions of my foundation?
The dimensions of the foundation will certainly vary. No compromises should be made when it comes to 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 its way up to 1.5 meters into the ground and cause damage accordingly.
Tip: A foundation depth of just over a meter is a good alternative for everyoneclimatic conditions in our latitudes.
The dimensions of the foundation will ultimately depend on the size of the greenhouse. The weight of your new greenhouse will determine the strength of the foundation.
Why does a foundation need a layer of gravel?
A layer of gravel under the actual foundation offers you additional security. The gravel should be at least ten centimeters deep, with slab foundations the same strength can be chosen as for the foundation itself. The gravel layer allows the water to run off better. This is especially useful if you have floors that are difficult to drain. There is a risk of waterlogging here, and very few plants tolerate waterlogging.
What is important when laying a concrete foundation?
| Step | Description |
| Measurement | The exact measurement of the foundation is decisive for the future position of the greenhouse. The best way to do this is to make a batter board and mark out the relevant area precisely. |
| Dig a ditch | The ditch must be at least 80 cm deep. In areas with a harsher climate, depths of 1.20 meters make sense. Digging is important to prevent moisture from getting into the greenhouse material and endangering its stability. |
| Insert concrete pipes | If a point foundation is to accommodate posts and supports, concrete pipes are let into the ground for this purpose. Here, too, precise measurements must be taken. A laser range finder, for example, can help here. Use a spirit level before pouring the concrete into the pipes. |
| Pour concrete foundation | Concrete foundations can be brick or cast from concrete slabs. Whether a concrete foundation really offers stability often depends on the dowels and screws that you use for attachment. Larger greenhouses require a concrete strip foundation. |
Wooden foundation as an alternative to concrete foundation
Foundations are commonly made of concrete, but you can also use some wood. The foundation consists of a wooden frame made of squared timber. The frame is additionally provided with longitudinal and transverse struts. The wooden frame is ultimately applied to point foundations.
What is a point foundation?
A point foundation can serve to accommodate your timber frame and secure it in the groundto anchor. For this purpose, anchor shoes are cast in the foundations. The squared timbers of the wooden frame can be attached there later. Point foundations are an inexpensive alternative to slab foundations. Furthermore, an optimal heat exchange is ensured. The moisture does not accumulate, but can dry out well due to the distance between the soil grain and the wooden foundation.
Create a spot foundation - step by step
- Dig Holes
- Apply foundation frame
- Fill holes with concrete
- Align the foundation frame precisely