What to look for in a commercial polytunnel

Largely used in agriculture, commercial polytunnels are the ultimate solution for growing crops and housing livestock. Recent advancements in technology and structural design now mean that polytunnels are fast becoming the preferred form of shelter in the farming sector, due in part to the affordability and excellent cover provided.

Each commercial polytunnel manufactured by Northern Polytunnels is built to withstand even the most extreme weather conditions, making them a cost-effective, hard-wearing choice for protecting sheep, cattle and other livestock from predators and prevailing weather.

Of course, polytunnels need not be the preserve of the livestock farmer; they can be used in a variety of applications, with growers and garden centres opting to employ their use in order to protect produce-bearing plants from the elements. When it comes to choosing a commercial polytunnel, there are a number of things to consider. In this article we'll take a look at the types of materials used, and why.

What exactly makes an effective commercial polytunnel?

From the ground up, all components of a polytunnel should be of an industrial grade. Weld fittings are used in order to keep the structure steady during high winds, and help to reduce any wear and tear on the PVC cover. For extra protection from the wind, 50mm bracing on all corners plus crop bars manufactured from high tensile steel are used to help stiffen up the structure, ensuring it remains rigid during wind and snowdrifts.

  • All frameworks used in a Northern Polytunnel is manufactured with pre-galvanised, high-tensile steel, which is approximately 48% stronger than standard steel materials. The ground tubes of a polytunnel are likely to be in contact with water for prolonged periods of time. By using a heavier-gauge galvanised ground tube, the risk of corrosion is significantly reduced.
  • Northern Polytunnels ground tubes have a 3.25mm wall thickness in order to withstand any forces applied to them. Before the structure is erected, it's important to construct a mass concrete foundation. This provides further protection to the steel of the ground tubes, and also increases the surface area in contact with the ground, increasing the resistance to sliding and overturning.
  • A concrete foundation also provides resistance against any uplift caused by strong winds.
  • Northern Polytunnels use aluminium for doors, since it is stronger and more durable than traditional timber constructions and easier to re-sheet, although 75x75mm tanalised timber with steel joints is used for the construction of the door frames.
  • Some polytunnel suppliers provide hoops in 3-5 pieces, mainly due to transport restrictions, although the fact remains that each joint in the structure creates a weak spot. Using less hoop sections (ideally two) will result in keeping a structure strong. Northern Polytunnels will only ever supply hoops in two sections, negating the need for optional storm bars.
  • In order to hold the sheeting onto the structure, base rails are used. Stronger base rails ensure that the sheet remains tight, which results in a better all-round performance and longer life span.
  • Some suppliers will suggest using anchor plates to secure a commercial polytunnel to the ground. At NP Structures, we believe this to be poor practice, on the basis that ground anchor plates require the foundation to be back-filled with loose topsoil, which is weaker than compact soil that has been naturally left undisturbed. Back-fill soil makes it easier for the anchor plate to pull away from the foundation.

Whilst commercial polytunnel designs may vary, at Northern Polytunnels we believe that our years of experience and expertise in the field provides us with the knowledge to provide the best commercial polytunnels the industry has to offer.