This house is a gothic arch film greenhouse built for a hot climate and a soilless crop. The roof section lifts above the line of the house and opens along its length, so the warmest air leaves without a fan, and the bay is clear enough to lay out channels, tanks and a return under the frame. 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.
In a hot climate the greenhouse has one job above all others: get the heat out. A house that holds the afternoon in is a house that loses the crop, and on a hydroponic layout there is no soil to buffer either the temperature or the water, so what the house does with the air it is sitting in decides the result.
A section of the roof is lifted above the line of the house and opens along its whole length. Warm air inside is lighter than the air outside, so it rises and leaves through that opening without a fan, and because the opening runs continuously rather than at intervals, the exhaust is spread along the building instead of concentrated at one end.
That matters where the external temperature stays high around the clock. The house cannot rely on the night to reset it, so the ventilation has to keep working through the middle of the day when the layer under the cover is at its warmest and the crop is working hardest. Houses of this family are grouped on the film greenhouse range page on this site.
A hydroponic house is laid out around the growing lines. Channels, tanks, the feed and the return are set to the crop and worked from a walkway, with the frame holding the cover and the trellis above them. Because the bay is clear of posts, a line can run the full length of the house instead of breaking around a column, which keeps a recirculating system simple to lay out and simple to reach.
It also changes what maintenance means. There is no soil to carry a mistake, so the solution reaches the crop within the same cycle and the tanks, the dosing and the return are checked on a schedule rather than when something looks wrong. A house built around the same roof and the same principle is described in the gothic sawtooth house with a hydroponic system.
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 and trusses 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 raised roof section is part of the frame geometry rather than an addition bolted on afterwards.
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 built for the same climate with a different vent arrangement is described in the naturally ventilated sawtooth house for tropical growing.
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 | Gothic arch roof with a raised sawtooth vent section |
| Growing layout | Hydroponic channels, tanks and return pipework under the frame |
| Cooling | Fan and pad cooling system optional; shade net 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 arches and the raised section go up together, the film is pulled over and tensioned from the ridge down, and the growing system is set out once the house is closed.
Maintenance divides into the structure, the air and the water. The ridge opening, the side openings and their gear are checked and greased before the season turns. On the water side the tanks, filters and return are cleaned on a cycle, because a blocked filter reaches the plants before it reaches an alarm. Where a shade net is fitted it is taken off and stored over the cool season.
Houses of this type are used for hydroponic tomato production, for leafy vegetables in channels and for herbs and flowers grown to a controlled schedule. They suit growers in a hot climate who need the house to keep venting through the middle of the day, operations moving from soil to a recirculating system, and farms that expect to add cooling, lighting or a control layer to the same frame later.
Research and extension material on protected crop production and controlled environment agriculture is published by the Controlled Environment Agriculture Center, University of Arizona. Production and market reporting for commercial growers is published by Krishijagran. The specification that matters is the one that still suits the crop ten years from now.
It gives the warm air a continuous way out along the whole house rather than at one point, and it works without power. Where the outside temperature stays high overnight the house cannot rely on the night to reset it, so the venting has to keep working through the day.
The frame stays the same, but the layout sets the clearance and the walkways. Channels, tanks and the return have to run under the frame and be reachable, so the growing system is usually drawn alongside the house before the span and height are fixed.
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 the growing layout you intend to run. We reply with a layout drawing and a full quotation.
