Tomato and strawberry both hang, which means the structure carries a crop as well as a roof. This house is quoted with the numbers that decide that: 50 kg per square metre of crop load, 0.3 to 0.5 kN per square metre of wind and snow, and 140 mm an hour of drainage off the gothic ridge. Gutter height runs from 2.5 to 5 metres, which is what makes multi-tier strawberry work inside it. Those four figures are the ones worth comparing line by line against any other quotation for the same crop.
Most tunnel pages describe a shape. This one is worth describing by its numbers, because a house that carries a hanging crop in a snow region is a structural question before it is an agricultural one. Wind load, snow load, crop load and drainage are all stated, and they are the four lines to compare against any other quotation. The house sits in the tunnel greenhouse range on this site.
Wind and snow are both quoted at 0.3 to 0.5 kilonewtons per square metre, and the figure that applies to your site is the one your engineer asks for. Crop load is capped at 50 kilograms per square metre, which covers a trellised tomato crop and the truss and wire that carries it, and is the number a multi-tier strawberry system tests first.
Asking for those three figures on a quotation is the fastest way to separate a house that was designed from one that was assembled. A supplier who cannot state them is quoting a shape, not a structure.
The frame is hot dip galvanized steel, assembled on site with galvanized connectors and fasteners and no secondary treatment afterwards. Cover is PO or PE film from 80 to 200 micron with anti-dew, anti-dust and anti-drip treatment, light transmission above 89 percent and diffusion at 53 percent.
The diffusion figure matters on a hanging crop: light that scatters reaches the lower trusses and the far side of a row, which is where a tomato canopy is thinnest. A nine metre house of the same family with a plainer section is described on the 9 m span commercial tunnel page.
| Type | Gothic arch steel frame greenhouse |
| Span width | 8 m / 9.6 m / 12.8 m, or custom |
| Section size | 4 m / 5 m, or custom |
| Length | 4 m x n or 5 m x n, or custom |
| Gutter height | 2.5 / 3 / 3.5 / 4 / 4.5 / 5 m |
| Wind load | 0.3 to 0.5 kN/m2 |
| Snow load | 0.3 to 0.5 kN/m2 |
| Crop load | Maximum 50 kg/m2 |
| Rain drainage | Maximum 140 mm per hour |
| Cover film | PO or PE, 80 to 200 micron, light above 89 percent |
| Working temperature | Minus 40 to 60 degrees C |
Gutter height is the working number on a hanging crop. At 2.5 metres a trellised tomato reaches the film by mid-season; at 4 metres there is room for the crop, the pipe rail and a person working above it. Strawberry on multi-tier gutters is the case that needs the top of the range, because the tiers stack upwards rather than along the floor.
Height costs steel, and it costs wind load: a tall house on an exposed site needs the closer section spacing to stay inside its rating. That trade is worth settling with the drawing in front of you rather than after the first season.
A pointed ridge sheds rain to the gutters instead of holding it, and the quoted figure is 140 millimetres an hour, which is a storm number rather than a drizzle one. What matters on site is the downpipe and the soakaway: a house that sheds well onto a yard that does not drain simply moves the water problem.
On a gutter-connected block, the gutters carry water from several bays, so the outlet sizing scales with the number of houses. Guidance on protected cropping and farm structures is published by Teagasc, and commercial farming coverage by Farmers Weekly South Africa.
Ventilation is at the top and the sides, by rolled film or opening windows depending on the order, with insect net available on the openings. Shade runs from 10 to 99 percent, external or internal, and cooling is normally a fan and pad wall sized to the volume. On a tall house the air volume is large, so the fan and the vent area are quoted together rather than chosen separately.
A house of the same family built for strawberry on a lower gutter is described on the strawberry tunnel greenhouse page.
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.
Both are quoted at 0.3 to 0.5 kN/m2, with crop load up to 50 kg/m2. Which end of that range applies depends on your site, and the rating on the drawing should match the figure your engineer gives you rather than a default.
2.5, 3, 3.5, 4, 4.5 and 5 metres. Trellised tomato is usually comfortable from 3 metres up, and multi-tier strawberry needs the top of the range. Height adds steel and adds wind load, so it is settled with the section spacing.
