This house is a multi span film greenhouse for agricultural production at commercial scale. The bays are joined along the gutter, so one block covers the ground with less wall and fewer doors than a row of separate houses, and the gutter line takes the roof water to downpipes instead of letting every bay shed on its own. The frame is hot dip galvanized steel, bolted rather than welded on site, and the cover is a three layer compressed PE film. Spans run from 8 m to 12 m and length from 10 m to 100 m.
Once a growing block gets past a certain size, the walls start to cost more than the roof. A multi span house covers the same ground as a row of single spans with less wall, fewer doors and one gutter line to manage, which is why it is the usual choice for agricultural production at scale.
Joining the bays along the gutter removes the wall between them, so the ground under the block is continuous and the walkways can run from one end of the house to the other. It also puts the roof water into one line instead of onto the ground beside every bay, which keeps the working area outside usable through the wet season.
The trade is in how the house is served. A large block is one environment rather than several, so the control, the irrigation and the crop plan are set for the block as a whole, and a problem in one bay spreads further before it is noticed. Houses of this family are grouped on the film greenhouse range page on this site.
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. Columns, trusses and the gutter line are bolted rather than welded on site, which leaves the coating intact and lets a damaged member be unbolted and replaced instead of cut out. The gutter is the member sized first on a multi span house, because it carries the roof water and ties the bays together.
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 on the same frame with a heavier cover is described in the heavy duty reinforced film house for vegetable farms.
Inside the block the bay width and the post spacing decide how many rows fit and how a trolley moves between them. Because the bays are joined, the crop can be walked from one end of the house to the other without going outside, which changes how the picking and the crop care are planned.
Ventilation works on the same principle. Openings at crop height and along the ridge are run together so the air crosses the canopy rather than passing over the top of it, and the openings are worked in stages through the day. A block built on the same arrangement for a specific crop is described in the commercial grade multi span house for vegetables and tomatoes.
The table below is the standard build. Span, length, height and cover 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, multi span, gutter connected between bays |
| Ventilation | Side wall openings and ridge openings |
| Gutters | Galvanized gutters between bays with downpipes |
| Crops | Tomato, cucumber, leafy vegetables, fruit and flowers |
| Customisation | Span, length, height and cover set to the site and the crop |
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 arches and trusses go up bay by bay and the gutters are levelled across the block as the bays are joined, and the film is pulled over and tensioned from the ridge down.
Maintenance divides into the frame, the water and the cover. The gutter line and the downpipes are cleared before the wet season, because a blocked outlet backs water into the bay rather than away from it. 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.
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 agricultural growers running a large block as one house, farms that are extending along the gutter line one bay at a time, and operations that expect to add cooling, irrigation or a control system to the same frame later.
Research and extension material on protected crop production, including work on the growing environment under cover, is published by Cornell University through its horticulture section. Agricultural sourcing and production information for growers is published by Wikifarmer. The specification that matters is the one that still suits the crop ten years from now.
It removes the wall between them, so the ground under the block is continuous and the walkways run end to end. It also puts the roof water into one line instead of onto the ground beside every bay, which keeps the working area outside usable through the wet season.
It is one environment rather than several, so control, irrigation and the crop plan are set for the block as a whole. That is simpler to run, but a problem in one bay travels further before it is noticed, which is why the openings and the water are checked on a schedule.
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.
