Flower crops are less forgiving of a sagging roof than vegetables, because a stem that bends under a low ridge stays bent. This tunnel runs from 2.5 to 5 metres at the ridge, which is the range where cut flowers and tall herbs can be grown standing rather than trained sideways. The frame is sized to carry a crop load of 15 to 30 kilograms per square metre, so hanging baskets and overhead irrigation are within what it was designed for.
A low cost tunnel is usually sold on price, which is the least useful number in the catalogue. What decides whether it works is the height at the ridge, the load the frame carries and how the cover is fixed. Those three are what this house is specified around.
At 2.5 metres the house is a crop tunnel. At 5 metres it is a working house that can take cut flowers, tall herbs or an overhead irrigation line without the crop touching the film. The same range is offered because the two jobs are different, and buying the tall version for a low crop wastes money in the frame while buying the low version for flowers wastes the crop.
The bay width runs from 0.5 to 3 metres, which sets how many arches a given length carries and how much the film is supported between them. A closer bay spacing costs more steel and holds a flatter cover, which matters on a windy site. Houses of this shape are grouped on the tunnel greenhouse range on this site.
The frame is hot dip galvanized steel with bolted connections. On a house sold at this price point the temptation is to save on the coating, and the coating is exactly what decides whether the frame is still standing in fifteen years.
The cover is polyethylene film tensioned over the arches and fixed at the base rail. The fixing detail matters more than the film thickness on a low-cost house: a cover that is loose will flap, and a flapping cover fails at the fixings long before the film itself wears out. A larger house on the same principle is described on the commercial single span greenhouse kit page.
| Structure | Single span film tunnel, hot dip galvanized steel frame |
| Span width | 6 m to 12 m |
| Bay width | 0.5 m to 3 m |
| Height | 2.5 m to 5 m |
| Crop load | 15 to 30 kg/m2 |
| Wind resistance | 45 to 65 km/h |
| Snow resistance | 30 to 55 kg/m2 |
| Rain capacity | 140 mm/h |
| Assembly | Bolted, no site welding |
The load figures are worth reading together rather than separately. A crop load of 15 to 30 kilograms per square metre covers the plants plus hanging baskets plus an irrigation line; snow resistance of 30 to 55 kilograms per square metre is the roof load; and the 140 millimetres per hour rain capacity is what the gutters and the ground around the house have to handle.
Wind at 45 to 65 kilometres per hour is a working range rather than a storm rating. On an exposed site that is the number to design against, and the answer is usually a closer bay spacing and a properly tensioned cover rather than a heavier arch alone.
The house is bolted together on a levelled base, with the cover going on last. Because the sections are pre-drilled, the crew is following a sequence rather than measuring on site, and the film is the only step that needs calm weather.
Maintenance is the cover first, the fixings second and the frame third. On a house this size the cover is a service item on a replacement cycle; the base rail and the end arches are where a cover usually starts to fail, and the frame needs an occasional check where the coating has been knocked.
Houses in this range are used for cut flowers and foliage, for herbs, for strawberry and soft fruit, and for vegetable production where a taller ridge is needed for the crop. They suit a flower grower who needs standing room, a horticultural operation adding covered area at a controlled cost, and buyers who want the height and the load rating specified rather than implied.
International horticultural trade information is published by IPM ESSEN. Horticultural industry reporting is published by HortWeek. A house on the same frame with a cooling system is described on the single span greenhouse with cooling system page.
A crop load of 15 to 30 kg/m2, a snow load of 30 to 55 kg/m2, and rain at up to 140 mm/h through the gutters.
Yes, in the taller versions. The ridge runs from 2.5 to 5 m, and flowers need the upper end of that range so the stems stand rather than bend.
Yes. We customize span width, bay length, gutter height, covering material (film, PC sheet or glass) and ventilation configuration. Share your crop type, local climate and growing area, and our engineers will size the structure to match.
The hot-dip galvanized steel frame carries a 10-year structural warranty covering structural safety, plus a 5-year warranty against corrosion perforation. It is designed for a 15-20 year service life. Film covers carry a 3-5 year UV warranty depending on grade.
Film suits low-cost tunnels on 3-5 year replacement cycles. Glass delivers the highest light transmission and the longest lifespan, at the highest cost. PC sheet insulates better than film and suits cold or high-humidity climates. The right choice depends on climate, crop and budget.
Ziyang Bozong Greenhouse Industry Co., Ltd. is a manufacturer based in Ziyang, Sichuan, China. We produce the hot-dip galvanized steel frame in-house, cutting and drilling to drawing, and supply covering materials, ventilation, cooling and irrigation systems as one coordinated package.
