Roll Up Side Ventilation Tunnel Greenhouse 10m Wide 40m Long Galvanized Steel Frame Kit

Heat build up, not cold, is what ruins most summer crops under film. On a still afternoon an unventilated tunnel in southern Spain or northern Nigeria can run 12 to 15 C above ambient, and blossom drop starts well before the thermometer reaches that point. This 10 m x 40 m house is built around air movement: full length roll up curtains on both sides, a 1.2 m ridge vent, and 40 mesh insect netting sized so the opening still passes air when the net is fitted. The frame is 60 x 2.0 mm tube at 1.0 m centres, hot dip galvanized at 275 g/m2, and the cover is 150 micron UV stabilised film so the whole wall can open without stressing the sheet.

• Full length side curtains: Two 1.8 m roll up walls, manual winch as standard, 0.75 kW electric motor with remote as an option. Opens in about 90 seconds end to end.
• 1.2 m ridge vent: Continuous ridge opening with a manual rack and pinion, so hot air leaves at the highest point instead of being pushed sideways.
• 40 mesh insect net on every opening: Fine enough to stop thrips and whitefly, with roughly 38 percent open area so airflow is not choked.
• 10 m clear span: No internal posts, so a 3 m wide sprayer or a small tractor can work the full length.
• 150 micron UV stabilised film: Three year UV package, 91 percent light transmission, anti drip additive to reduce condensation dripping on foliage.
• Hot dip galvanized frame: 275 g/m2 after welding, with stainless clips at the curtain track to avoid galvanic corrosion.

Greenhouse ventilation is usually specified as a percentage of floor area, and for summer tomato or pepper production the target is 20 to 25 percent of the floor plan in open vent area. On this 400 m2 house, both curtains at 1.8 m give 144 m2 and the ridge vent adds a further 48 m2, so the house reaches about 48 percent with everything open. That margin matters on days when the wind drops. Buyers often compare only the film price and skip this calculation, then add fans later at three times the cost of a proper ridge vent. If your crop is lettuce or herbs, 30 percent is adequate; for tomato and cucumber in hot climates, insist on the full package.

The 150 micron film is a compromise this house is designed around: lighter than 200 micron, easier to handle on a 40 m run, and cheap enough to replace every three to four seasons, which is what commercial growers in high UV zones do anyway. The outer layer carries the UV blocker and the anti drip additive sits on the inner face so condensation runs to the gutter instead of spotting fruit. Diffusion is 35 percent, which spreads direct light and reduces leaf scorch on the south wall in summer. If you farm in a hail belt, ask for the 200 micron version and add the optional hail net; the same frame accepts both.

Curtain tracks are the first thing to fail on a cheap tunnel, so we use a 1.5 mm aluminium lock channel rather than a rolled strip, and stainless steel spring clips instead of galvanized ones that rust at the contact point. The curtain hem carries a 20 mm steel pipe as a weight bar, which keeps the sheet taut at 35 km/h gusts. End frames have diagonal bracing and the first and last bay get double purlins, because that is where wind load concentrates on a 40 m house. Ground anchors are 700 mm galvanized stakes with a 45 degree pull test on the first ten of every project.

Stand the arches with a crew of four over three days on a level, compacted pad; the curtains and net go on in half a day after the film is tensioned. Set the curtain opening height before you plant, because the bottom rail position decides how much air reaches the canopy. In practice growers open the upwind side first thing in the morning, add the ridge vent when the internal temperature passes 24 C, and close down at 60 percent humidity in the evening to hold warmth. The winch handles are removable so nobody can open a curtain by accident during a storm.

Tomato, pepper, cucumber and melon under 10 m spans in Spain, Morocco, Turkey, Mexico and Uzbekistan; leafy greens and herbs in Nigeria, Kenya, Ghana and Indonesia where the sides stay open all day; strawberry and raspberry in Portugal and Chile where the house is used mainly as a rain shelter. A 10 x 40 m set loads into one 40HQ at about 34 cubic metres with the film rolls packed separately, and two sets can be combined into a 40HQ high cube if the frame bundles are nested.

Film, net and hardware are packed in separate cartons so nothing sharp touches the sheet in transit. Each bundle carries a bay number that matches the drawing, which cuts erection time noticeably on site. Inspection covers tube wall thickness with a micrometer, zinc weight by weigh strip method, curtain track straightness, and a full trial assembly of one bay with the net fitted. The frame is warranted for 10 years and the film for 3 years, and we keep curtain track, clips and winch parts in stock for a decade. A bilingual installation sheet and a video link travel in the document bag.