ISHS Acta Horticulturae 170: Greenhouse Construction and Covering Materials
EXPERIENCES ON DAMAGES TO ROOFING-MATERIALS AND GREENHOUSE CONSTRUCTION |
| Author: | G.-W. Bruns |
| Abstract:
Concerning possible causes of damages hail, windstorm, snow- and ice-pressure, and fire are discussed. A report is given on damages to glass as "classic" roofing-material and to different kinds of plastic materials which have been in use since the early seventies. Hailresistance of glass generally depends on its thickness and sort. As to plastics resistance does not only depend on the raw material and thickness of the sheets but also on their finish, age and temperature. Even more important than physical and chemical qualities of roofing-materials are economic consequences in the case of damage. Those are very different. It depends mainly on the material itsself and the kind of damage wether sheets have to be replaced or can be repaired. Also protection of persons, plants and equipment within the greenhouse given by the roofing-material varies widely. In fact, legal requirements can exclude some materials from special purpose. The risk of damages by windstorm to different roofing-materials hardly arises from the material but is determined by character and quality of mounting. The risk is increasing with larger sheet-sizes. Unlike glass most of the damages by snow- and ice-pressure to plastics occur in combination with damages to greenhouse framework. As to fire-damages to greenhouses one has to differentiate between cause and spreading of the fire. Practically, inflammability of the material is mainly important for the spreading. Damages to greenhouse construction are sometimes caused by deficiencies in greenhouse planning and workmanship. Also later manipulations on statical important elements of greenhouse framework can turn out to be a reason for damages. | |
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