Overview

The dramatic entrance structure to Kimberlin Library has been given a new lease of life.  When the original canopy, made from PTFE:Teflon coated glass fibre, began to show signs of wear and tear in 2007, the solution was to re-skin the structure using type II PVC coated polyester.

The structure is a complex twin layer design incorporating a variety of fixing methods and systems:  cable edge clamps, headrings, flying trusses, etc.  The front projection of the structure was designed to flex under high wind loads, and this flexing caused areas of the fabric to begin cracking and tearing whilst under tension.   PTFE was clearly an unsuitable material for this design and the flexibility of a polyester fabric coated in PVC would resolve this problem.

Design solution
Architectural fabrics all have differing characteristics, one of which is their biaxial stability.  The amount a fabric ‘stretches’ during installation is very small: normally less than 1%.  However, over only a few metres this ‘stretching’ begins to affect the overall form and must be compensated for during the patterning of the canopy.  Changing the canopy from PTFE to PVC meant each panel making up the new canopy had to be re-sized to ensure that it tensioned out evenly, exactly matching the shape of the original.

Installation was complicated by having to maintain access to the library entrance throughout, however the canopy fitted perfectly without a hitch.  All the fabric hardware: clamps and membrane plates, was re-usable and helped keep the project within budget.