Growing vegetables and herbs at your dacha is possible not only in open ground but also in a greenhouse. The choice of greenhouse structure plays a key role in obtaining a bountiful harvest. Polycarbonate greenhouses are considered the most practical and functional, but before purchasing, it's important to consider the criteria for choosing a structure.
Frame material and design
The frame is the main structural element that holds the polycarbonate in place. Typically, metal pipes or galvanized profiles are used to construct the supporting frame.
In the past, wood was often used for this purpose, but it's uneconomical because over time, the material begins to rot, and the frame's reliability and load-bearing capacity are reduced. Metal profiles are more cost-effective: they're strong and inexpensive, yet durable and capable of withstanding heavy loads.
Galvanized bent profile
Galvanized bent profile is the best material for building a frame in terms of price and quality. It's inexpensive and lightweight, but it can't withstand very heavy loads.
This problem is resolved as follows:
- To make the frame made of galvanized profile stronger, an increased number of elements are used.
- The joints of the frame elements also require separate reinforcement.
- The thickness of galvanized metal profile does not exceed 0.8 mm, so this material is not suitable for all regions.
A greenhouse with such a frame can only be built in areas without strong winds or snowy winters. Otherwise, the material simply won't withstand the weight of snow or gusts of wind, and the integrity of the greenhouse will be compromised.
Rectangular or square steel section
A more practical frame would be one made of square or rectangular steel profile. It can withstand loads well, but the material itself requires additional treatment with special anti-corrosion compounds.
Aluminum frame
An aluminum frame is assembled from pipes or profiles. This material has many advantages. Firstly, it is easy to install, and the structure itself is lightweight yet strong enough to withstand wind and mechanical loads. Secondly, such frames are rust-resistant and require no additional treatment.
But don't forget the disadvantages. An aluminum frame will cost more than a similar structure made of steel profiles, and the greenhouse itself will lack sufficient thermal insulation, making it unsuitable for use in winter.
What type of polycarbonate should be used for a greenhouse?
The frame coating, in this case polycarbonate, also plays a crucial role in the successful operation of the structure. When choosing a coating, consider the type of polycarbonate, its thickness, and the presence of a light-stabilizing layer.
Polycarbonate comes in two types: cellular and solid. For greenhouses, cellular is best. Due to the internal cross-links, this material is resistant to damage and has a long service life.
Sheet thickness also plays a significant role. It determines how much light enters the greenhouse and whether the covering can withstand the weight of snow in winter. Typically, polycarbonate with a thickness of 4-10 mm is used for greenhouses. Sheets with a thinner thickness are less able to withstand gusts of wind, and thicker materials do not transmit light well.
The presence of a light-stabilizing layer and its thickness
High-quality cellular polycarbonate absorbs all ultraviolet rays, but only visible and infrared rays penetrate the room. These rays ensure the full growth and development of plants.
To protect the outer surface of polycarbonate from the harmful effects of UV radiation, a special light-stabilizing substance is applied. The presence of this coating is indicated by special stickers. If these stickers are missing, it is best not to use this polycarbonate for greenhouse cladding.
Deciding on the shape of the greenhouse
There are several types of closed-ground structures, depending on the arch shape. Each has its own characteristics, advantages, and disadvantages, so it's worth examining the most popular types in more detail.
Arched greenhouse with lifting sides (butterfly greenhouse)
The butterfly greenhouse is ideal for small garden plots and is used to grow small quantities of vegetables and herbs for the needs of one family.
The main advantage of this type of greenhouse is that its side walls lift up like butterfly wings. This allows the owner to easily access any part of the garden bed.
Greenhouse with a drip-shaped arch
The drip greenhouse frame consists of two arches that form a sharp ridge where they meet. This unique shape prevents snow from accumulating on the surface. Additionally, an additional stiffening rib runs along the top, increasing resistance to wind and mechanical stress.
Drip-type greenhouses are typically quite spacious, but they are difficult to build yourself due to the unusual arch shape. Given this, many gardeners prefer to buy ready-made greenhouses, pre-assembled.
Gable greenhouse
This is a classic greenhouse, shaped like a small house. It has a rectangular base and straight vertical walls, ending in a gabled roof.
Experience shows that this type of greenhouse is best suited for DIY construction. Simply mark out the site, construct the foundation frame, attach the vertical supports, and erect the roof. This type of greenhouse can be built from any materials, including those found on hand. However, keep in mind that snow will accumulate on the roof during the winter, which can damage the polycarbonate.
Does a greenhouse need a foundation?
Most small greenhouses used only during the warmer months don't have a foundation. This has its advantages: they're inexpensive to build and still perform their basic functions quite effectively. However, for those living in regions with strong winds, this option isn't ideal. Greenhouses without a foundation have increased windage, so strong winds can tip the structure over.
If the greenhouse will be used not only in summer but also in winter, the foundation must be a mandatory stage of construction. Typically, a strip foundation is built, to which the vertical frame supports are later welded.