Choosing the type of greenhouse foundation and methods of support installation

Choosing the design and foundation material

Ready-made frames made of aluminum, steel, or timber are often supplied with a greenhouse. They are stable but do not provide good protection for seedlings against frosts and soil pests. For reliable protection, it is better to lay a strip foundation of brick and concrete below the soil frost line.

• Minimum strip width — 10 cm
• Ground clearance height — 30 cm
• Kerbstone width — 10 cm
• Kerbstone length — 50–100 cm

For foundation construction, ready-made concrete blocks or L-shaped forms are also used, which are filled with concrete after installation. Another cost-effective option is a kerbstone laid in a concrete mixture. A strip or ready-made frame foundation is quite sufficient for film greenhouses and solar-heated structures.

If the foundation base is raised above the ground, it will increase the height of the greenhouse at the ridge and allow for the installation of additional hanging shelves for seedlings. However, a high threshold will make wheelbarrow access inconvenient. To solve this problem, make ramps on both sides of the door or order a greenhouse with a lowered door opening.

DIY reinforced concrete foundation posts

Wooden greenhouse supports buried directly into the ground rot within two to three years. To extend the service life of the frame, use reinforced concrete square-section posts (foundation stubs) as a foundation. They can be cast independently right on the site using collapsible wooden formwork.

• Proportion of cement in the mixture — 1 part
• Proportion of sand and fine gravel — 2 parts each
• Gravel fraction size — up to 10 mm
• Rebar diameter for a 10x10 cm post — 6–8 mm
• Rebar length margin — 3–5 cm

Steel wire with a diameter of 6 to 10 mm is used to reinforce the posts. For a 10x10 cm section post, it is sufficient to tie a frame of four longitudinal bars. The formwork is assembled from well-planed boards, pre-treated with drying oil.

1. Install the wooden form on a level surface covered with parchment paper or roofing felt, and secure it to the ground with metal pins.
2. Mix dry cement with sand, gradually add water to the consistency of thick sour cream, and then mix in gravel moistened with water.
3. Pour the first layer of concrete about 3 cm high into the form.
4. Lay the wire-tied rebar frame so that the lower bars are submerged in the solution, and fill the form with concrete to the very top.
5. Compact the mixture with a narrow shovel with a straight edge, insert anchor bolts, and leave the blank to gain strength.