This house is a gothic arch film greenhouse on a hot dip galvanized steel frame, built around ventilation so that a vegetable crop is not left in still air. The roof profile lifts the ridge above the eaves, which gives the working height in the middle of the bay and a slope that sheds to the gutter. The cover is a three layer compressed PE film with side openings for crop level air. 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 film house in a warm or changeable climate lives or dies on how well it clears the air over the crop. The vegetable crops that go into these houses close down in the afternoon if the canopy stays warm and humid, and a wet canopy at night is where disease starts. Both problems are answered by where the openings sit rather than by how much cover the house has.
The warmest air in any greenhouse collects in the layer just under the ridge, because that is where the air that has passed over the plants ends up. Without an opening at that height the house holds it all day and the crop loses the afternoon. The second layer that matters is the one the leaves are actually in, and a ridge opening on its own does very little for it.
That is why the two openings are specified together. The ridge exhausts the top layer and the side openings supply replacement air at crop height, so the bay is swept rather than just vented. Houses of this family are grouped on the film greenhouse range page on this site.
The side openings run along the wall at crop height and are the first thing opened in the morning and the first closed when the sun goes off the house. Because they are at the height of the plants, the air that enters crosses the canopy on the way to the ridge, which is what keeps the layer inside the leaves from sitting there all afternoon.
Air in a gothic profile house also moves with less obstruction than in a flat roofed one, because the arch carries the warm air up and along the bay rather than letting it pool between the ridges. A tunnel house with a ridge opening and side vents is described in the gothic arch tunnel house with roof vents.
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 gutter 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, which means a panel can be released and retensioned without a full recover. A single span house in the same family is described in the gothic arch single span house with a triple layer cover.
The table below is the standard build. Span, length, height, cover and vent 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 | Gothic arch roof, multi span |
| Ventilation | Ridge opening and side wall openings at crop height |
| Cooling | Fan and pad cooling system optional |
| Crops | Leafy vegetables, tomato, cucumber, fruit and flowers |
| Customisation | Span, length, height, cover and vent positions 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 openings and the film. The side wall gear and the ridge opening 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. A gutter and downpipe check before the wet season keeps water leaving the block instead of backing into the bay.
Houses of this type are used for leafy vegetable production, for tomato and cucumber crops, and for flowers and herbs grown in soil or in bags on the floor of the bay. They suit growers in warm and changeable climates who need the house closed down on a cold morning and opened out again the same afternoon, and operations that expect to add cooling, irrigation or a control system to the same frame later.
Standards for greenhouse structures and for the materials used in them are published by ASTM International. Production and market reporting for commercial growers is published by Agriculture India. The specification that matters is the one that still suits the crop ten years from now.
They clear different layers. The ridge takes the warm air out from under the roof and the side opening brings replacement air in at the height the plants are in, so the air crosses the canopy instead of sitting in it.
It carries warm air up and along the bay rather than letting it pool between ridges, and it gives the working height in the middle of the span where the trellis and the crop are, while keeping the gutter at the wall line between bays.
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, snow and rain figures. We reply with a layout drawing and a full quotation.
