This house is a single span tunnel greenhouse clad in plastic film, built for tomato production at commercial scale. The bay is clear of internal posts, so rows run the full length of the house and the crop is worked and picked without breaking around a column, and the arch carries the film at an even tension across the span. The frame is hot dip galvanized steel, bolted rather than welded on site. Spans run from 8 m to 12 m and the length is set anywhere from 10 m to 100 m, or built to client demand.
A tunnel house is the plainest way to put a tomato crop under cover, and on a farm that runs several houses the plainness is the point. One clear bay, no posts in the rows, and a cover that can be replaced without working around a multi span roof: the house does its job and stays easy to repair.
Tomato is grown on rows, and rows want to run the length of the bay without breaking around a column. A single span tunnel gives one clear width from wall to wall, so row spacing follows the crop and the picking trolley rather than the structure, and the trellis and the irrigation main can be laid out to the crop instead of fitted around it.
It also keeps each house separate. One block can be cleaned, turned over or recovered while the house beside it is still cropping, which matters when the season is being run as a sequence rather than as a single crop. Houses of this family are grouped on the tunnel greenhouse range page on this site.
Once a tomato canopy closes over the rows, the air inside it stops moving on its own. That layer is warmer and more humid than the rest of the bay, which slows pollination once the afternoon turns hot and is where leaf disease starts after the evening irrigation. The openings are what decide whether that layer is cleared or left sitting there.
Opening the gable and the side walls brings the intake down to crop height, so the air that enters crosses the canopy on the way to the outlet instead of passing over the top of it. The walls are worked in stages through the day and closed again when the sun goes off the house, which is what extends the season at both ends. A house on the same frame with roll up side walls is described in the single span house with roll up side walls.
The frame is hot dip galvanized steel, galvanized after the sections are formed, so the zinc reaches the bore of the tubes, the cut ends and the inside of every drilled hole. Hoops, purlins and the base rail are bolted rather than welded on site, which leaves the coating intact and lets a bent hoop be unbolted and replaced instead of cut out.
The cover is a three layer compressed PE film. The layers carry their additives separately, so the anti condensation face keeps working for longer than a single layer sheet does, and the outer layer carries the UV stabiliser. Film is held on the hoops and the base rail with clips, so a panel can be released and retensioned without a full recover. A house in the same family on a wider bay is described in the commercial single span tomato house.
The table below is the standard build. Span, length, height, cover and openings are set to the site and to the crop.
| Greenhouse span | 8 m / 9 m / 10 m / 11 m / 12 m |
| Greenhouse length | 10 m to 100 m, or built to client demand |
| Greenhouse height | 3 m to 8 m, or custom |
| Structure material | Hot dip galvanized steel pipe, bolted assembly |
| Cover material | Three layer compressed PE film |
| Roof type | Arch roof, single span with no internal columns |
| Ventilation | Side wall openings at crop height and gable openings |
| Cooling | Fan and pad cooling system optional |
| Crops | Tomato, cucumber, leafy vegetables, fruit and flowers |
| Customisation | Span, length, height, cover and openings set to the site |
The kit arrives formed and drilled with the fittings, so the work on site is bolting and tensioning rather than fabrication and no welding is done at any point. Ground posts or a base rail are set to the drawing first, the hoops and purlins go up bay by bay, and the film is pulled over and tensioned from the ridge down before the side openings are fitted.
Maintenance is mostly about the film and the openings. The side wall gear and the gable openings are the working parts, so they are checked and greased before the season turns. Film tension is checked after the first season and the cover renewed on a planned cycle, while the galvanized frame runs for far longer than the film does. Bolts and the base rail are walked once a season.
Houses of this type are used for tomato and cucumber production, for leafy vegetables and for fruiting crops grown in soil or in bags on the floor of the bay. They suit commercial growers running a block of tunnels through the season, farms extending a range one house at a time, and operations that expect to add irrigation, cooling or a control system to the same frame later.
Research and extension material on protected crop production, including work on high tunnel and season extension systems, is published by the National Greenhouse Manufacturers Association. Agricultural news and market reporting for commercial growers is published by Farmer's Weekly SA. The specification that matters is the one that still suits the crop ten years from now.
Clear width and independence. A single span tunnel has no columns in the crop, so rows run the full length of the bay, and each house can be cleaned or turned over on its own. A multi span covers the same ground with fewer walls.
Through the gable and the side walls, which bring the intake down to the height the plants are in so the air crosses the canopy rather than passing over it. The openings are worked in stages through the day rather than set once.
The galvanized steel frame is rated for 15 to 20 years under normal growing conditions. The film cover runs on a shorter cycle than the frame, typically 3 to 5 years depending on UV exposure at the site.
We provide a 10 year structural warranty and a 5 year anti-corrosion warranty on the galvanized frame. Details are set out in the contract for each project.
Send your site dimensions, the crops you plan to grow and your local wind and snow figures. We reply with a layout drawing and a full quotation.
