All of these retail greenhouses begin with a top-down powerful design. This design integrates growing with the retail customer, while still being cost-effective. Utilizing one center purlin, the semi-gothic arch shape offers maximum headroom for customers and employees — even close to the sides of the house. To ensure customer comfort, as well as street appeal, the slightly peaked roof is attractive while reducing potential problems of condensate dripping. Withstands high winds and adverse weather. Structures Unlimited. (800) 541-8129.