Multi-Span polytunnels make the best use of your available space as there are no redundant areas between each bay, typically around 20% higher at the apex. But due to the extra height being in the 'leg' they have approximately 25%-30% greater air volume, providing a more harmonised environment that is less susceptible to sudden temperature fluctuations.
The cost per m² of multi-span polytunnels is usually similar or slightly less than single-span polytunnels – depending on the size of the structure and the options you choose. Although multi-spans are higher and incur the additional cost of gutters, this is countered by the relative reduction of side vents (i.e. whatever the number of bays, you still only have two sides). The gutters also act as side purlins, and so the extra strength they provide allows the hoops to be spaced a little further apart (thus reducing costs) without compromising the integrity of the structure.
Our 26ft (8m) wide bays have almost 24% more floor space than a 21ft (6.4m) bay, yet the price difference is only around 8%. Likewise, the cost of a 4-bay multi-span polytunnel that has 26ft (8m) wide bays would be around 10% lower cost than one with 5 x 21ft (6.4m) wide bays, even though they are approximately the same size. It’s a similar picture with the 30ft (9.1m) bays, although the gains aren’t as great as we generally prefer to include bracing bars (crop bars) with this width of the structure. Therefore our 26ft (8m) wide bays are the most popular as they offer the best value in terms of cost and strength.