How do you build a greenhouse cheaply and easily? Our guide outlines how to build a greenhouse step by step and save money.
If you have looked around the market, you will quickly have noticed that greenhouses are not exactly cheap and mostly only available as prefabricated versions. That’s why we thought that a manual to build yourself should be found and we inquired. The next steps will help you to build an individual and functional greenhouse.
Find the right location
Of course, it depends on what you will need the house for most. If you want to use it in summer for Mediterranean plants that are particularly warm, you should orient it to the south in order to capture maximum light. If you are more interested in giving your plants a frost-free place to overwinter or planting young plants, it makes sense to orient the house in an east-west direction. It is also an advantage to surround the greenhouse with bushes or something similar so that the wind does not hurt it so much.
Very important: Find out from the responsible building authorities whether your building project is compatible with legal requirements (distance to the plot boundary, driveways, etc.).
Tools to build a greenhouse step by step
- Impact drill for screwing and drilling
- Concrete mixer for mixing
- Standard spirit level to check that everything is straight
- Construction angle to check the angles
- Mason’s cord to measure the foundation
Materials to build a greenhouse step by step
- Square timbers as a framework for the greenhouse
- Wooden struts in support of the roof
- concrete for the foundation
- Angle connector for connecting the wooden structure
- Post baseto fix the posts
- Twinwall plastic or polycarbonate as window panes or even entire walls
- Screw profile for twin-wall sheetsfor connecting the twin wall sheets
- Marking spray for marking the foundation size
Consider temperature-controlled windows
You always want to create the right climate for your plants, but you don’t have the opportunity to constantly check the temperature and humidity during the day? An automatic window opener with a temperature measuring device is the solution.
How to build a greenhouse step by step
1. Define the floor plan
Now that you have a location, you can start planning more precisely. Measure how much space the greenhouse should take up in the garden. Make a note of the length and width of the floor plan. Calculate an additional 15cm on each side so that you have enough space to work.
2. Stake out a foundation
When you have measured and marked out the area of the foundation, you should dig the ground about 30cm deep. It will help if you connect the corner pillars with masonry cords and mark the edges with marking spray. You should also use a straightedge to determine whether the surface is level. A construction angle can be used to check whether all angles are 90 °. You can also measure the diagonals for this purpose.
3. Preparation of the subsoil
Now you lift the ground about 30cm deep. Depending on the ground and size, you may even need a mini excavator. To be on the safe side, use your straightedge to determine if there is a slope and in which direction.
4. Level the surface
If you have previously determined that there is a slight slope , you should compensate for this with gravel . Then the first part of the ballast must be evenly distributed over the entire surface and pressed down with a vibrating plate so that a solid foundation is created. Repeat the process with a second load of crushed stone until the ground is filled up to six inches. Check with the straightedge with a spirit level whether the surface is flat.
5. Assemble formwork planks for the concrete pouring
Now you saw to make formwork planks the same size as the foundation . They should be the height of the planned foundation and have appropriate outer edge lengths. Note the strength of the shuttering boards themselves so that it really fits in the end. With the bricklayer’s square, you can already check whether the right angles are correct. Then they are nailed together.
6. Prepare the formwork shell for the concrete pouring
You need to be really careful when aligning the formwork. The frame must be absolutely flat, which is best checked several times with your spirit level. If necessary, line up crooked corners with some gravel. Then you attach structural steel all around so that the shell stays in position in any case. Line the surface with PE foil, let it protrude a little on the sides, it prevents the concrete from drying too quickly.
7. Mix concrete properly
It is best to mix the concrete according to the manufacturer’s instructions . Prepare a robust mixture, because the soil has to be able to withstand a lot. The components should be carefully stirred in the concrete mixer for 4 or a maximum of 5 minutes, when the mass then has a viscous sheen, it can be poured into the bowl and evenly distributed up to a height of 10cm. Now steel mats are overlapped with concrete tie wire and placed in the foundation.
8. Finish the concrete surface
Now you pour more concrete up to the top of the remaining area . An internal vibrator can distribute the concrete even more evenly and prevents air bubbles. At the end of the concrete is straight edge neatly pulled smooth . Place a PE film over the fresh concrete and fix it. To prevent the concrete from drying too quickly and cracking, the tarpaulin must be kept moist. After a day or two, the formwork can be removed safely, but the concrete has to cure completely for up to 6 days before it can be used.
9. Preparation of the basic construction
We’re planning a medium-sized greenhouse. For this you need four pillars each 2m high. To do this, we take two pillars of the same height to support the long sides. For the long sides you need nine posts, five to connect the pillars from above and four to connect them to the ground. Note that the latter have to be shorter because they should fit between the pillars.
10. Preparation of the roof
For the roof construction you need six pillars of the same length, which must be sawn off at an angle so that they lie flat on the support beam. You also need another bar that corresponds to the long side of the greenhouse, it will later become the roof ridge. Otherwise, only three central beams are missing, which additionally support the roof ridge.
11. Measurement of the roof ridge
It is best to lay out the support beams as they will be built up later and measure how long the sloping roofs will have to be by trying them out. Note, however, that the roof should have a slope of at least 26 ° so that rain and snow slide off it. In addition, you need some narrower struts that hold the glass, as well as 4-6 struts corresponding to the long side for stabilization. In preparation, you should carefully prime all square timbers and struts with a wood preservative.
12. Build the scaffolding
The four to eight basic pillars are mounted using screw-on post bases . Measure the space again beforehand and make sure the corners are square. Then you drill the required holes and screw the beams to the concrete. Insert the posts and connect them to the beam.
14. Stabilize the framework
Now you can place the support beams. Screw them from below along the beam using angle connectors to the base pillars. Do the same on the floor with the bars for the gaps.
15. The roof structure of the greenhouse
For the roof you now take the cut square timbers and screw them to the support beam using angle connectors . You also have to connect them to each other at the roof ridge. Other, narrower struts, which you attach in the same way, serve to attach the glass roof. Cross struts also support the roof.
Choices for walls and windows
Glass, foil or twin-wall sheets?
You now have several options to continue. You can either build proper frames and use polycarbonate sheets or use twin-wall sheets (plexiglass). Both let the light through well, the twin-wall sheets also insulate even more – but this can also be problematic if you forget to use a window. The simplest solution would be to apply a greenhouse film.
Glazing and windows with hollow brackets
We find that twin-wall sheets now look a little better than the film and are also very practical thanks to their insulating function. Therefore, you have to screw the screw profiles to the roof and outer wall at the correct intervals according to the size of the hollow clamp plates and clamp the plates. You build a door or window by designing a separate frame and attaching it with the help of hinges. You have now built a great new greenhouse yourself, congratulations!