The arch on this house is pointed rather than round, and that one change does two things: snow slides off instead of sitting on the crown, and rain reaches the sides faster. On a small tunnel that is often the difference between a structure that survives a hard winter and one that needs repair in spring. At 6 by 12 metres it covers 72 square metres, a size that suits a market garden or a nursery bench line rather than a broadacre block.
Most small tunnels are built on a round arch because it is the simplest shape to bend. A pointed arch costs a little more in frame and returns it twice: snow and water leave the roof instead of resting on it, and the ridge sits higher over the crop for the same shoulder height.
A round arch carries snow load across the crown, which is the weakest point of a film tunnel. A pointed arch sheds it: the slope either side of the ridge is steep enough that snow slides before it builds up. The same slope moves rainwater to the sides quickly, so the film is not holding a pond after heavy rain.
The shape also raises the ridge. At 3.2 m at the top against 1.5 m at the shoulder, there is standing room along the centre even in a house only 6 m wide. Houses of this shape are grouped on the tunnel greenhouse range on this site.
The frame is hot dip galvanized steel pipe, bolted throughout. The cover is 180 micron PE film, a working thickness for a house this size: heavy enough to tension properly over the arch, light enough not to load the frame.
The side openings are 1.2 m high with a manual film roll and 40 mesh insect net. A 1.2 m opening is generous on a 6 m span, and it is the part a grower works every day, so the roll mechanism matters as much as the size. A larger single span house on the same principle is described on the commercial single span greenhouse kit page.
| Structure | Gothic arch single span, hot dip galvanized steel pipe |
| Width | 6 m (20 ft) |
| Length | 12 m (40 ft) |
| Shoulder height | 1.5 m |
| Top height | 3.2 m |
| Growing area | 72 m2 |
| Cover film | 180 micron PE film |
| Side ventilation | 1.2 m high, manual film roll, 40 mesh insect net |
| Door | One, 2 x 2 m |
| Supplied with | Installation manual and video guide |
| Customisation | Width, length and height can be made to order |
Two side openings are the whole ventilation system on a house this size, and they work well because the span is narrow: air crosses a 6 m width without mechanical help. The insect net is what makes the opening usable through a season with pests about.
The 2 x 2 m door is worth noting because it is larger than most small tunnels carry. It takes a barrow, a wheeled bench or a small tiller, which changes how the house is worked rather than only how it is ventilated.
The house arrives as a kit with an installation manual and a video guide, which is the part that matters for a first-time buyer: the sequence of arches, purlins and film is shown rather than described. Assembly is bolted, with no site welding to burn the zinc off the joints.
Maintenance is the film and the tension. The cover is checked at the base rail and at the end arches, the two places a tunnel cover usually starts to fail, and the roll-up mechanisms are kept free so the sides still open in the season they are needed.
Houses at this size are used for vegetable and salad production, for strawberry and soft fruit, for seedling and nursery lines, and for flowers. They suit a market garden that wants covered area without a building, a nursery adding a propagation house, and buyers who need a repeatable standard size that can be ordered again rather than a bespoke structure.
Research and technical guidance on protected horticulture is published by Wageningen University and Research. Commercial vegetable growing reporting is published by Growing Produce. A polycarbonate version of the same span idea is described on the polycarbonate sheet greenhouse page.
Snow and water leave a pointed roof instead of resting on it, and the ridge sits higher over the crop for the same shoulder height.
Galvanized frame, 180 micron PE cover, two side openings with manual rolls and 40 mesh net, one 2 x 2 m door, plus an installation manual and video guide.
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.
Send your growing area, span and length, crop type and local climate. If you already have a layout drawing, that is enough to start. Our engineers then return a quotation with a structure drawing and a bill of materials.
The hot-dip galvanized steel frame is designed for a 15-20 year service life in normal agricultural environments, with a double-sided zinc coating of 200-275 g/m². Film covers are replaced every 3-5 years, while glass and PC panels carry their own manufacturer warranties.
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.
