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Having your own greenhouse in your garden is becoming increasingly popular. Do you have some DIY skills?
We’ll show you how to build one yourself, what you’ll need, and have prepared a guide for you.

Greenhouse types

There are three main types: the most commonly chosen freestanding greenhouse, which is placed on an 80-centimeter-high foundation; the lean-to version, which is attached to an existing facade and therefore consists of three instead of four walls; and the sunken greenhouse, or earth house, which is placed in the ground and thus allows for planting at ground level. The following instructions refer to the sunken version with a film cover, but you can certainly add a foundation to it.

foundation

• Wood
  A wooden foundation has the serious disadvantage that it is generally shorter-lived than the greenhouse it stands on. Soil moisture, in particular, reduces its durability. However, its advantage is its quick and uncomplicated assembly.
• Concrete:
  A concrete foundation provides a robust and durable base. It’s the best choice for large greenhouses, as it retains its shape even under heavy loads. However, laying the concrete foundation requires a significant amount of work and time. For a freestanding greenhouse, the base slab must be 80 centimeters thick. In addition to constructing the formwork, a longer drying time is required depending on the weather.
• Steel:
  The simplest and usually most cost-effective solution for smaller greenhouses is a stainless steel foundation made of stainless aluminum or zinc. This is a type of frame that is anchored in the ground. The floor of the greenhouse remains “open soil” and can be covered with floor slabs or similar materials if necessary. Properly anchored and with attention paid to high-quality materials, a steel foundation will ideally last forever.
• Ground/Slab Foundation:
  With ground or point foundations, a base slab is constructed that covers the entire area of the greenhouse. This provides 100 percent protection against pests climbing up from the ground. However, this option is rarely chosen because it is costly.
• Strip foundation
  With a strip foundation, you place a hard foundation beneath the outer frame of the greenhouse. For structures with four walls, a “strip” is placed under each side, onto which the frame is placed. This has the advantage of easily compensating for uneven ground and keeping out unwanted garden visitors like mice and snails. It can be constructed from lawn edging stones or poured from concrete.
• Point foundation:
  With a point foundation, you simply place a slab beneath the support beams. This could be, for example, a 50 x 50 centimeter exposed aggregate concrete slab. The encasing of anchors, for example, falls under point foundations. The disadvantage is that weathering can lead to subsidence or uplift. As a result, there is a risk that the greenhouse on top will warp, thus losing essential properties/functions or even being destroyed.

Greenhouse cladding

To ensure that light flows smoothly into your new greenhouse and heat is stored, various materials are available for the greenhouse cladding:

• Glass:
  Glass is the classic choice for greenhouse cladding. It has a light transmittance of between 89 and 92 percent. It’s easy to clean, weather-resistant, and ideally lasts for several decades. Glass also contributes to overall stability. However, keep in mind that Central Europe is increasingly plagued by storms, and glass breakage from flying debris is not uncommon. The material is also heavy, which is something you should definitely consider when choosing a foundation.
• Plexiglas twin-wall sheets.
  These Plexiglas sheets are made of plastic with an air layer inside. This serves as insulation, resulting in a higher insulation value than glass. This offers advantages, especially in winter, for the pre-cultivation and overwintering of frost-sensitive plants, but can also have disadvantages due to the buildup of high humidity. However, Plexiglas twin-wall sheets have lower light transmission than glass. Furthermore, it is relatively expensive and susceptible to hail. When purchasing, you should definitely stick to Plexiglas, as many other types of plastic yellow quickly and become even more opaque.
• Film:
  Film is the cheapest and simplest type of cladding. However, it doesn’t last very long, as it tends to get very dirty and is difficult to clean. This, in turn, leads to increasingly poor lighting conditions.

Instructions for a sunken plastic greenhouse

The specifications in this guide are for a wooden greenhouse with a height of 2.3 meters, a width of 1.1 meters, and a length of 2.75 meters. If you’re planning a larger or smaller greenhouse, the specifications will need to be adjusted accordingly. It’s important to always work at a height of over two meters, which ensures sufficient oxygen.

Materials required:

• Square timbers 5 x 5 centimeters
  > 4 x 0.55 meters
  > 7 x 0.9 meters
  > 2 x 0.925 centimeters
  > 8 x 1 meter
  > 4 x 1.50 meters
  > 1 x 1.60 meters
  > 8 x 2 meters
• Exterior wood primer/weatherproof wood preservative
• 8 angles 40 x 40 x 40 millimeters
• nails
• 28 screw hooks, straight, M4 with 3.5 x 40 millimeters
• 28 eyelets
• sufficient wood screws with 5 x 80 millimeters
• Greenhouse films
• roofing felt

Preparations:

1. Paint wood with primer/protective agent and let it dry
2. Cover 2-meter square timbers at one end with 30 centimeters of roofing felt

Build the body:

1. Attach a 1.5-meter-long square timber between two 2-meter square timbers at right angles to the opposite end of the roofing felt
2. Place 0.55 meter squared timber with screws in the middle of the short squared timber to fix the roof peak
3. Formation of the roof slope with two 1 meter squared timbers with right angles at the top
4. You need this construct four times – so repeat it three more times

Pull the slide:

1. Cut the foil for the back wall and nail it into the wooden frame
2. Cut film for each element from one side of the greenhouse to the other (three strips each 5.70 x 0.9 meters)
3. Attach 0.925 meter long square timbers to the center of the two outer foil strips
4. Nail 0.9 meter squared timbers to the edges of the outer lanes
5. Nail 3 more 0.9 meter long squared timbers to the middle track
6. Wrap foil several times around squared timbers
7. Cut the foil for the front area and attach it with nails at the top
8. Provide film edges with eyelets
9. Wrap 1 meter of square timber for the floor finish in foil and nail it in place.
10. Add additional eyelets evenly to all squared timbers (approximately eight per timber)
11. Connect all four elements
12. Insert 0.9 meter squared timbers into rectangular roof slopes (must be cut to the appropriate angle and fastened with screws)
13. Insert square timbers into the ground or a foundation up to the top of the roofing felt
14. Lay the film strips over the wooden frame, screw in the screw hooks at the eyelet height and hang the film
15. Nail the foil in the roof area

Glass and plexiglass instead of foil:

If you want to use glass or Plexiglas instead of film, additional steps and materials are required.
For glass, you’ll need glass frame strips, which you install around the timber frame. For Plexiglas panels, special profiles are available that need to be installed.

questions and answers

What is the best location for a greenhouse?
A suitable location meets several requirements: sheltered from the wind, away from trees, and plenty of sun.

Is a building permit required to build a greenhouse?
This varies from state to state. As a precaution, you should contact the relevant building inspectorate before beginning construction and inquire.

Is it worth buying a greenhouse kit?
There’s no price difference between building one yourself and using simple kits. If you’re not very handy, a greenhouse kit is the better choice.

Can these instructions also be used for a greenhouse with a concrete foundation?
Yes. To do this, install squared timbers placed horizontally around the perimeter as soil stabilizers. Secure these to the concrete with brackets. Even better is to use a steel frame, which you can make yourself or buy ready-made.