- Greenhouse or greenhouse
- How greenhouses are classified
- Greenhouse shape – not only aesthetics
- Greenhouse frame – material characteristics
- Translucent greenhouse fences – material characteristics
- How to build a greenhouse yourself
In this Article: Classification and Shape of Greenhouses characteristics of the materials used for the greenhouse frame; types and characteristics of translucent fences; a detailed description of the process of building a greenhouse with your own hands.
If somewhere in the subtropics there is constant summer and all year round vegetable crops grow in open ground, then the temperate climate does not dispose to this. Morning frosts and frequent off-season precipitation force gardeners to wait until more or less favorable weather sets in – days and weeks go by, they go to waste … The greenhouse, as part of the country landscape, will protect spring seedlings from the vagaries of the climate, create optimal conditions for plants to grow and mature. You just need to decide on the construction, but how to build a greenhouse, how to correctly orient it on the site and what material to use in its construction – the answers to these and a number of questions that have not yet arisen are contained in this article.
Greenhouse or greenhouse
The purpose of such structures is to protect the planted plants from changing weather conditions. Both in greenhouses and in greenhouses, an atmosphere favorable for plants is created due to the infrared radiation of the Sun, the heated air is retained by a vapor-tight roof. But if the greenhouse is a temporary solution, usually used for growing seedlings, then the greenhouse is a complete structure that provides a full cycle of growing cultivated plants from seedlings to harvest ripening.
In terms of their design, a greenhouse and a greenhouse are in many ways similar – a transparent roof covering, placement in open ground, often an oval shape of the ribs forming the structure. The difference in size – the height from the soil to the roof in greenhouses is sufficient for the free movement of a person, while greenhouses are rarely higher than one meter from the ground level, and workers’ access to plantings inside them is made by partial dismantling of the roof. A polyethylene film is most often used as a roof covering for greenhouses, which is sufficient in case of sudden cold snaps to -3 ° C, and a more solid material is used to overlap the greenhouse roof – glass, or durable polymer coatings.
It is simple to arrange a greenhouse – you need a wire with a diameter of 5 mm or more, cut into pieces with a semi-oval shape, with their subsequent fixing in the ground along the protected beds and overlapping with polyethylene on top. The device of the greenhouse is more complicated – more on that later …
How greenhouses are classified
First of all, greenhouses differ in the purposes of their use – they can be seedlings and vegetables. If vegetable greenhouses are designed for a full growing cycle and are in many ways similar, then seedlings are more specialized, because the seedlings grown in them are intended for indoor or open ground, which affects the organization of ventilation and technical equipment.
By service life – all year round or only during the growing season. The design and organization of year-round greenhouses is much more complicated than seasonal ones, which do not require additional heating, a serious foundation and artificial lighting of plants..
By the frame and by the type of translucent fencing. In most cases, greenhouse frames are rigidly fixed to a permanent foundation, however, in the northwestern regions of Russia and Ukraine, greenhouses with mobile frames are used, which allow growing seedlings over a larger area and accelerating the growth of perennial crops. Translucent greenhouse fencing is divided into film, glass and rigid polymer coating..
By design and layout – into block and hangar greenhouses, along the profile in cross section – into single and gable ones, with slopes of hyperbolic and flat-cylindrical shape, equal and unequal to each other.
According to the cultivation technology, greenhouses are divided into ground, shelving and hydroponic. The difference between the first two types is in growing crops directly on the ground, cut off from the external environment by the inner perimeter of the greenhouse, or in containers with soil isolated from the ground, placed above the base of the greenhouse at several vertical levels. Greenhouses with hydroponics, depending on the applied method of growing crops, are equipped with more complex and varied equipment. When choosing a method for feeding a solution with nutrients through ordinary flooding, plants are kept in sealed racks and pallets filled with expanded clay or granite crushed stone. In modern hydroponic greenhouses, drip irrigation is used, and plants are grown in racks filled with peat or stone wool.
Greenhouse shape – not only aesthetics
The mismatching height of the walls, the height differences of the ridge of the roof on opposite sides, the bizarre shape of the roof itself, the absence of visible standards in width – the point is not in the eccentricity of the greenhouse designer, but in the preferences of the crops growing in it. For example, the width of the greenhouse is directly related to the method of planting the plants – for the formation of beds, a wider greenhouse is required than with vertical-rack cultivation..
Arched greenhouses are widespread both in private gardening and in large greenhouse complexes – it’s all about their simplicity. The semi-oval edges of the frame are placed in a row at a certain distance, they are connected to each other by longitudinal ties, a translucent enclosing covering is stretched over it, most often – a cheap plastic film.
Disadvantages of arched greenhouses: almost “dead” zones are formed at the edges, where only low crops can be grown, which have to be looked after, bending almost into “three deaths”. Another serious drawback is associated with ventilation, the openings for the device of which are possible only in the end sides, because it is extremely difficult to arrange oval-shaped swing openings on the semi-oval sides. Attempts to organize the flow of fresh air through the doorway are ineffective, since hot air accumulates in the “dead” zone near the ceiling. The only relatively effective solution is a window at the end above the doorway.
Combined greenhouses, consisting of elements of a straight and arched structure, have strictly vertical side and end walls, their roof is arched. This design solves the problem of “dead” zones at the side walls, but there is still a problem with ventilation.
Round greenhouses are actually formed by a multifaceted frame and look quite attractive. But this shape requires additional ventilation openings, because window openings cut into the roof alone will not be enough – you will need to arrange at least one overlapping opening in the vertical wall. A greenhouse-pavilion is most often used for growing flowers and ornamental crops, its shape tempts owners to arrange a gazebo, but it is difficult to arrange rectangular furniture in such a room without affecting the planting.
Greenhouses adjacent directly to a residential building are convenient for economic reasons – they require a smaller area, savings on building materials are achieved, they are easier to heat, you can get inside right from the house, i.e. there is no need for warm outerwear during the cold season. The disadvantage of such greenhouse extensions is one, but very serious – low illumination.
Greenhouse frame – material characteristics
A frame made of wood, most often from spruce or pine, is chosen by gardeners for several reasons – it is simple to process and no special tool is required, it is relatively inexpensive and illiquid assets available in any dacha will be used. However, a wooden frame will not last more than 3-4 years. You can, of course, create a solid frame from a thick bar, arrange the arches of the ribs close, thereby protecting the greenhouse roof from possible pushing under a mass of snow, treat the frame wood with an antiseptic (drying oil or linseed oil) or paint it annually – but all these measures will increase the service life greenhouses for two years.
The metal frame will last a long time, but it is better to purchase it as a ready-made kit, because independent production of a greenhouse from pipes is quite complicated. First of all, do not try to put a frame for a greenhouse made of a metal profile used for fastening drywall and ventilated facades – it is not strong enough for this and the entire structure of the greenhouse will inevitably collapse under atmospheric precipitation. When creating a frame for an arched greenhouse from a steel pipe of a round or square profile, a problem arises – how to give the segments a semi-oval shape. In the conditions of a summer cottage, it is almost impossible to perform this operation; a pipe bender is required. Painting the metal frame is mandatory (condensation will collect on the metal), first with a layer of primer, then with high-quality enamel – this operation must be carried out at least twice a year, for this reason it will be easier to create a frame from a galvanized profile.
The greenhouse frame made of aluminum profile has a number of advantages – it does not rust and does not require painting, is lightweight and durable, attractive in appearance. However, it is expensive and requires assembly skills. A greenhouse with an aluminum frame is more suitable for a winter garden than for growing vegetables or flowers.
A modern material for a greenhouse frame is a pvc profile, the advantages of which are in a relatively low price, ease and in the complete absence of any maintenance during operation, with the exception of periodic washing. But this material is suitable only for small greenhouses or in combination with a metal profile – to cover an area of more than 2 m2 the load-bearing properties of the pvc profile will not be enough. In addition, it is possible to cover the greenhouse frame made of pvc profile only with a polymer film..
Translucent greenhouse fences – material characteristics
Glass is a classic material, with its fragility and weight having the highest light transmittance equal to 90%. Glass fences retain heat well even in the absence of heating in the greenhouse, are not exposed to ultraviolet radiation, they can be painted, shading plants during the season of solar activity. The minimum glass thickness for covering greenhouses is 3 mm, the glass sheet should not be cloudy and contain air bubbles that can focus the sun’s rays.
Polyethylene sheeting is more popular for fencing greenhouses, but is also used for covering greenhouses. Among other types of overlapping greenhouse frames, ordinary polyethylene has the lowest characteristics – it is not strong, subject to destruction from ultraviolet radiation, low heat retention rates, its light transmittance is not higher than 80%. Films made of ethylene octanevinyl and fluoroplastic (polyvinylidene fluoride) have high characteristics in terms of strength, wear, light transmission and heat retention, but they are expensive and difficult to obtain.
The roof of the greenhouse can be covered with sheets of acrylic – it is lightweight, with a thickness of up to 2.5 mm it is equal in light conductivity to glass, is resistant to bending and is applicable in creating volumetric vaults, is not subject to destruction by ultraviolet light and therefore is durable. The main disadvantage of acrylic is its insufficient strength, which is why, for example, holes in it cannot be drilled with an electric drill and only cut with a hand hacksaw.
Cellular polycarbonate in the creation of greenhouse structures is becoming more and more popular – it is flexible, has a low weight and low thermal conductivity, is 200 times stronger than glass and is practically equal to it in light transmission. To cover the roof of greenhouses, 10 mm polycarbonate is used, for the walls – 4 mm. Cutting and processing is done with ordinary carpentry tools. Not all brands of cellular polycarbonate are protected from ultraviolet radiation, so the presence of a protective layer in this brand must be confirmed by a certificate.
How to build a greenhouse yourself
Often, the owners of summer cottages choose a place for a future greenhouse, based only on the layout of the site, which is fundamentally wrong. The priority will be the needs of the plants grown in the greenhouse, and they require the sun’s rays – the more, the better. The position of the greenhouse along its ends should be oriented from east to west, slightly shifting the direction axis to the south – in this case, the sun’s rays will penetrate into the greenhouse in summer and winter at a sufficient angle. The distance from buildings to the greenhouse should be at least 5 meters, but not more than 10 – the location of the greenhouse should be visible from the main building, in addition, it will be easier to bring communications to it (water, electricity). The selected area should not be shaded by trees and buildings. Should be protected as much as possible from the cold winds blowing out the surface of the translucent fence, drawing out heat.
To achieve the best microclimate in the greenhouse, its maximum height should be no more than 2.5 m, the height of the side walls – no more than 1.5 m, the maximum width – up to 3.8 m.The length of a single-section summer cottage greenhouse can be in the range from 2, 5–3 m to 6 m, depending on the availability of a free plot of land and the seriousness of the summer resident’s intentions, because the more space in the greenhouse, the more work there is. When building a greenhouse with a length of 6 m and more, it is required to introduce into its structure internal pillars supporting the roof – in increments of 2 m. A longer greenhouse (more than 6 m) will need to be divided into sections, growing only one crop in each of them. When planning the dimensions, consider the following layout of the beds and paths: two parallel beds with a width of 0.8 to 1 m; near each side wall, paths with a width of 0.6 to 0.7 m are arranged; in the center between two beds, another path is needed with a width of 0.5 to 0.8 m.
Before starting the foundation work, you need to choose the material of the frame and the translucent fence, decide whether to make the greenhouse structure yourself or purchase a ready-made one. The cost of a finished metal frame of a greenhouse with dimensions of 3×4 m and a height of 2 m, with sheets of cellular polycarbonate prepared for it, will average 20,000 rubles, the cost of a metal frame alone is about 7,000 rubles. Please note that manufacturers often include a minimally durable cellular polycarbonate in the finished greenhouse kit – it is better to purchase it separately, making sure of sufficient thickness and the presence of a protective layer from ultraviolet radiation.
Having decided on the location, size and frame, we proceed to create the foundation. In the case of the purchase of a ready-made frame, do not take on faith the assurances of manufacturers that their greenhouse does not need an additional foundation. The foundation will be required in any case, unless you want one day to find it thoroughly damaged due to seasonal soil deformations.
We mark the greenhouse area, completely remove the 200 mm topsoil. We ruthlessly sweep aside the options for foundations made of timber and brick – they are unreliable. We arrange a strip foundation under the greenhouse: we tear off a trench along the perimeter to a freezing depth (for moderate latitudes – more than a meter), up to 250 mm wide; put gravel on the bottom with a layer of 50–70 mm, then a 200 mm layer of sand with compaction; then we expose the formwork made of extruded polystyrene foam for insulation of the foundation, rising above the ground level by 50-70 mm (upon completion of the foundation casting, the protruding polystyrene foam should be covered with a layer of plaster) to protect it from flooding in the off-season, from the inside of the greenhouse perimeter outside the expanded polystyrene slate formwork we break or roofing iron (minimizing the chances for weeds to enter the greenhouse from the outside). When preparing the foundation trench, consider the water pipe entry. Along the perimeter of the trench, a welded or bonded lattice of 9 mm reinforcement is placed, L-shaped metal embedded or anchor bolts are placed at the corners and sides of the perimeter (step – 0.5 m) for future fastening of the greenhouse frame to the foundation, concrete is poured. More details about the composition of the concrete mix can be found in the strip foundation device for the bath. After pouring the concrete, the installation of the greenhouse in the place of its location is stopped for 5 days – we are waiting for the concrete to harden.
The following describes the construction of the frame of a gable greenhouse 2.53 m wide, 3.1 m long, vertical walls 1.8 m high.
Important: Before starting installation work, it is necessary to cover all the wooden elements of the frame with two layers of drying oil, waiting for each of the layers to dry completely!
A timber of 50×100 mm is attached to the mortgages, a cutout for the door is left at the end of the greenhouse, set aside for the doorway – 0.83 m.At the corners and on the sides of the base (the pitch corresponds to the mortgages – 0.5 m), a bar of 50×50 mm, length 1.8 m, temporarily fixed to the base bar with nails, given a strictly vertical position along a plumb line, then rigidly attached to the base with metal corners on self-tapping screws 50 mm long. For greater confidence in the strength of the frame, the corner posts, fixed to the embedded beam and the horizontal beam above the side posts are replaced with a steel corner. The side and corner posts are additionally attached to each other – diagonally, with a 40×50 mm bar. The queue of the door frame – it will be 1.9 m high, it will be formed by a 50×50 mm timber fixed to the side posts.
A cornice (timber 50×50 mm) is attached to the ends of the corner and side posts on metal corners with self-tapping screws – make sure it is in its horizontal position before final fixing using the building level!
We take on a gable roof: we remove from the attachment points of the vertical posts of the lateral sides sections of a bar 2 m long, with a section of 50×50 mm – first the end ones, between which a ridge with a section of 50×100 mm is attached, then intermediate ones. Installation of roof racks is carried out with 200 mm protrusion of each beyond the boundaries of the sides. The connection angle of the roof posts must be 20-30 °. Between each other, the central roofing racks are fastened with a 40×50 mm bar (ventilation vents will be installed there), at the ends they are propped up with a vertical bar coming from the eaves. Permanent fastening of roof elements is carried out through a metal strip and corners on self-tapping screws.
The door leaf is assembled from a beam of 40×50 mm, in addition to the frame along the perimeter, stiffeners from a 40×180 mm board are inserted into its structure at the top, bottom and in the middle, hinges are cut in with an indent of 260 mm from the ends. The vents are assembled from a T-shaped profile 40x20x4 mm. The doors and vents are equipped with a rubber seal; for their assembly, secret self-tapping screws 30 mm long are required.
The next step is glazing. The glazing area of this greenhouse will be 50 m2, glasses are fixed with L-shaped glazing bead with 3-4 mm groove, glass sheets are butt-joint. Roof glazing should start from the ridge, walls – from the bottom up.