Most tunnels ventilate at the sides only, which works until the crop needs the hot air out of the ridge rather than the cool air pulled in at the base. This house has both: roll-up sides and roof vents, hand or motor driven. It runs 6 to 10 metres wide with a 4.5 to 6.5 metre ridge, on hot dip galvanized pipe from 25 to 60 mm, with internal gutters and downspouts rather than open eaves. It is a working house rather than a showpiece, and the parts list is written the same way.
A tunnel with side rolls only is a chimney with the top closed. Air comes in low and has nowhere to leave except back out of the same opening, so the ridge stays the hottest point in the house. This one vents at the ridge as well, which is the difference between a house that works in July and one that is opened up and hoped for. It sits in the tunnel greenhouse range on this site.
Side vents and roof vents are both quoted, hand operated or motorised. In practice a grower uses them in sequence: the roof vent opens first thing as the ridge warms, the sides follow once the crop is transpiring, and both close in the late afternoon while the house is still warm enough to dry the leaf before nightfall.
Motorised operation is worth its cost on a long house, where the walk from one end to the other twice a day is the real expense. On a house under thirty metres, a hand crank is honest and has nothing to fail.
The arches are hot dip galvanized steel pipe from 25 to 60 mm, chosen by span, in wall thicknesses of 1.5, 1.8 or 2.0 mm. Every part is prefabricated and bolted, so no welding burns the zinc off at the joints. The cover is UV stabilised PE or PO film at 120 to 200 micron with anti-drip and anti-fog treatment, quoted for three to five years outdoors.
| Structure type | Single span arch greenhouse |
| Width per span | 6 m / 8 m / 9.6 m / 10 m, custom |
| Length | 20 m to 100 m or more |
| Ridge height | 4.5 m to 6.5 m, by span width |
| Frame material | Hot dip galvanized steel pipe |
| Pipe diameter | 25 / 32 / 40 / 48 / 60 mm |
| Pipe thickness | 1.5 / 1.8 / 2.0 mm, custom |
| Covering | UV stabilised PE or PO film, 120 to 200 micron |
| Film lifespan | 3 to 5 years |
| Ventilation | Manual or motorised side and roof vents |
| Drainage | Internal steel gutters with downspouts |
| Foundation | Embedded with anchor bolts |
Water leaves the roof into an internal steel gutter and down a downspout rather than off the eaves onto the beds. On a house where the crop runs to the wall, that detail decides whether the outer row is usable after a storm. The gutter also gives the film a straight line to be clamped to, which is where a cover usually starts to work loose.
Direct from the factory means the quotation is built from the drawing rather than from a catalogue: span, length, pipe diameter, wall thickness, film grade and vent drive are all chosen, then the frame is cut, drilled and galvanized to that list. The shipment is a flat pack of arches, purlins, base rail, gutters, film rolls, clamps and the drawing set.
What it does not include is the crew, the base line and a calm day. Those three decide how the finished house looks, and they are the buyer's side of the order. Standards for structural and agricultural equipment are published by CEN, and agribusiness and crop input reporting by AgriBusiness Global.
The reference crops are strawberry, mushroom and hydroponic vegetables, and the reason is the vent arrangement rather than the floor plan. Strawberry and mushroom both want a dry leaf and a moving air mass, and both suffer when a house is opened only at the base. Hydroponic lettuce and herbs want the same thing for a different reason: a gutter system transpires hard and needs the ridge open.
A house of the same family built for nursery propagation is described on the plastic film tunnel page, and one specified for strawberry on the strawberry tunnel greenhouse page.
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.
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.
Both are offered, on the sides and at the ridge. Motorised drive is worth the cost on a long house where the walk end to end happens twice a day; under about thirty metres a hand crank is simpler and has nothing to fail.
The arches are embedded and fixed with anchor bolts rather than set on a poured slab. The anchor pattern should be checked against your wind load, because a ten metre span carries more uplift than a six.
