4x4 PC Polycarbonate

"The Ultimate in Crop Protection"

Small Greenhouse

The large truss of the 12.8m span, combined with columns of 4.125m to the gutter gives equivalent growing conditions to a traditional Venlo design of over 5 metres without the associated heat loss.

Ingenious design using unique sleeve jointing systems patented by Harford's to ensure a top quality structure built to exacting standards at a very realistic price.

The 4x4 Polycarbonate greenhouses are computer analysed to provide full crop loading of 15 kg/m and at the same time resistance to wind loads of up to 50 metres per second.

The 4x4 is easy and quick to build, the strength of a fully welded connection is combined with single sleeve joint systems to give a simple on-site assembly without the need for expensive scaffolding or cranes. As the polycarbonate comes in light weight sheets, our construction teams can continue working in conditions which would be unsuitable for covering a plastic or glass covered greenhouses. In the highly unlikely event that some of the polycarbonate is damaged, individual sheets can be easily replaced- you may even be able to buy a suitable sheet at your local building supplies store.

Tomato, Capsicum and Cucumber growers will find that they can easily fit over 16 rows of crop per 12.8m span and 12 rows in a 9.6m span, giving effective use of space. While at the same time the height of the 4x4 offers ease of layering and crop management. Flower growers and Nurseries will find that the large span and height provides more efficient space for benching and automatic watering and gives a manageable buffer zone above the crop.

Another benefit of the truss design is the ability to use it for support when maintaining the vents, even when a full crop is planted. The trusses are constructed using galvanised high tensile steel. The truss spans are in multiples of 1.6m, matching international standards.

The polycarbonate cladding we use is of the highest quality currently available, giving light transmission of over 90%. It is available with an optional light diffusing texture to reduce shadowing in the greenhouse and allow more light to the lower levels of plants such as tomato's. The product is also available with an optional anti-drip coating. We include both of these as standard. The polycarbonate has outstanding impact performance over a wide temperature range, -40°C to +120°C. In addition, the product is virtually unbreakable in case of storms, hail-stones etc. The hail simulation test shows that it can withstand hail stones with a typical diameter of 20mm at speeds higher than 21 m/s.

There is no better protection for your valuable crop available on the market today.


  • Ultra-strong profiled polycarbonate cladding gives the best possible hail protection.
  • Top quality polycarbonate gives light transmission of over 90%. Available with or without light diffusing texture. Available with or without anti-drip coating
  • Available in 9.6m or 12.8m spans to provide super efficiency.
  • Column height is 4.125m at the gutter.
  • 4m section size (truss to truss) reduces shadows.
  • Modular construction allows simple cost effective growth.
  • Galvanised high tensile steel frame
  • Huge 45% floor area ventilated by gull-wing vents ensures complete control of the interior environment
  • University tested wind and crop loaded structure withstands winds up to 50 m/s (180 km/hr), with a crop load of 15 kg/m
  • Continuous vent hinge gives massive strength to the vent design while providing a highly effective seal against wet weather.
  • Large heavy duty walk-in gutter system designed to take heavy tropical downpours on the outside while the inside profile minimises shadow on the crop and provides anti drip condensation run off.

Standard Specifications

Size: Truss span 12.8 meter or 9.6 meter . Single or gutter connected multi-bay. Length modules (section size): 4m.

Truss Profile: Galvanised steel A-frame truss, straight sides.

Covers: Profiled 0.8 mm polycarbonate. 90%+ light transmission, available with anti-drip coating and light diffusing texture. UV protection to one side. 7 year warranty.

Ventilation: Double gull-wing ridge vents.

Automation: Single or three phase gearmotors as standard. Temperature, wind and rain control systems available up to fully computerised environmental control system. All built to customers specification. Misting, fogging and energy screen systems can be supplied if required.

Doors: One, two or three meter openings.

Construction: All steel framing sleeve connected.

Supply: Kitsets available ex factory Christchurch