This is a tunnel house supplied as a kit rather than as a built structure. The frame is hot dip galvanized steel on a Gothic arch, so the crown is steep enough to shed snow on its own, and the covering is a double layer of film held apart by an inflation blower, which is what keeps the interior temperature steady overnight. The side walls are roll up curtains, opened for summer cooling and closed again when the weather turns. Pipes come pre cut to the span and length and the film arrives in rolls, so the kit is packed flat and assembled on site.
A tunnel house is the simplest way to put a crop under cover, and the version that holds up in winter is the one with a steep roof. This kit pairs a Gothic arch frame with a double film cover and roll up sides, and ships with the tubes already cut to the span and length so the house is assembled rather than fabricated on site.
The kit is supplied as a set rather than a shopping list. Hot dip galvanized tubes come cut to the span and length, with the connectors, the fasteners and the arch sections matched to them, and the cover arrives on rolls with the fixings that hold it. Bulk kits are built for a specific site, with the span and the length set on the order, and the whole set packs flat on pallets so it takes a shipping volume that follows the pipe count rather than the house footprint. Houses of this family sit with the rest of the tunnel greenhouse range on this site.
The frame is built on a 120 degree arch. On a shallow round arch snow settles on the upper faces and stays there until it is cleared or the frame is built heavy enough to carry it. On the steeper Gothic profile the snow slides off under its own weight, which is the difference between a house that is brushed down after every fall and one that is left alone.
The same shape helps in wind, because the steep upper faces present less flat area to a gust than a wide round crown. Galvanizing is applied after the tubes are formed and drilled, so the cut ends and the bolt holes carry the same coating as the rest of the member and no painting or secondary treatment is needed once the house is up.
The standard cover is a PO or PE film of 80 to 200 micron with anti drip, anti fog and anti ageing treatment, light transmission above 89 per cent, diffusion of about 53 per cent and a working range of -40 C to 60 C. The film is fitted as two layers separated by an air gap and kept apart by an inflation blower, which is what gives the house its insulation. Where a rigid cover is wanted, UV treated twin wall polycarbonate panels can be specified instead.
The side walls are roll up curtains. In summer they are wound up to let the house flush through, and in winter they are closed down and become part of the insulated envelope. A kit house built on a square section frame instead of a Gothic arch is described in the square profile PE film tunnel greenhouse page.
The table below is the standard kit. Span, length, height and the accessory list are set to the site and to the crop.
| House type | Single span gothic arch tunnel |
| Arch angle | 120 degree gothic arch |
| Span | 8 m, 9 m, 10 m, 11 m or 12 m |
| Length | 10 m to 100 m or set to the site |
| Working height | 3 m to 8 m |
| Structure material | Hot dip galvanized steel |
| Cover | Double layer PO or PE film, inflation blower |
| Film thickness | 80 to 200 micron |
| Light transmission | Above 89 per cent |
| Diffusion | About 53 per cent |
| Working temperature | -40 C to 60 C |
| Rigid cover option | UV treated twin wall polycarbonate panels |
| Ventilation | Roll up side curtains, end vents |
| Irrigation | Drip irrigation hooks in the frame |
| Shading | Shade net 10 to 99 per cent, optional |
| Crops | Vegetables, tomato, leafy greens and cut flowers |
| Packing | Pre cut pipes with film rolls, flat packed for shipping |
| Customisation | Span, length, height and accessories set to the site |
The kit is assembled on site from pre cut tubes. Ground posts or a base rail are set to the drawing and levelled first, because a tunnel carries its load down the two side lines. The arches go up bay by bay, the purlins and the diagonal bracing follow, the end walls are framed, and the two film layers go on last with the blower connected so the air gap is closed before the house is used.
Maintenance follows the cover and the vents. The film is checked for chafe where it crosses the frame and at the fixing points, since a rub mark becomes a tear in the first gale, and the roll up curtain mechanism is cleared and checked at the start of each season. Fixings are gone over before the windy months and again after them, and where a rigid cover is used the panels and seals are inspected for the first few seasons. Drip lines hung from the frame are flushed on the same routine as the crop.
Kits of this type are used for vegetable and tomato production on beds or on a gutter system, for leafy greens under a shade net in summer, and for cut flowers on a schedule. They suit a grower putting up a first block of tunnel houses, a farm extending an existing row of tunnels to the same span, and projects that need the houses shipped as kits to a site where fabrication is not available.
Standards for greenhouse structures and their components are published by BSI. Market and crop reporting for growers in South Asia is published by Agriwatch. A house of the same family grown for vegetables is described in the greenhouse for vegetable growing page.
Because the air gap between the two layers is the insulation. A single sheet loses heat as soon as the outside temperature drops, while two layers held apart by an inflation blower keep the interior temperature steady through the night.
On a 120 degree arch it does. The upper faces are steep enough that snow slides off under its own weight rather than loading the frame, so the house does not have to be brushed down after every fall.
The galvanized steel frame is rated for 15 to 20 years under normal growing conditions. The film cover, the inflation blower and the curtain mechanism run on their own service cycles and are replaced as they come due.
We provide a 10 year structural warranty and a 5 year anti-corrosion warranty on the galvanized steelwork. Details are set out in the contract for each project.
Send your site dimensions, the crop you plan to run and the growing layout you intend to use. We reply with a layout drawing and a full quotation.
