Petrol-station canopies are usually highly standardised, engineered down to a cost and deliberately obtrusive for marketing purposes. At Weserpark, near Bremen in Germany, the canopy was required to be in keeping with the expressed steelwork of the rest of the retail park, a more expensive approach than the usual basic canopy structure.
The park opened in 1990 and the station, with its canopy designed by architect Helge Kropik, was built last year.
The steel structure is a pitched roof - a client choice - on four columns, framed with perforated edge beams and principal rafters. Purlins support glazing bars, with dry-glazed polyester sheet glazing spanning continuously from ridge to eaves. One slope is 10m, the other 7m; the canopy is 34m long.
While other buildings use laminated glass, Kropik chose the 6mm polyester sheet (see box) partly because of its lower cost and partly because it is half the weight of laminated glass. He was also looking for a particular balance of light transmission and shading, both for petrol-station customers and in order to provide shading to the clear glazing of the attached shop. Opal-white material with 30 per cent light transmission was readily available, although 10m lengths Above: petrol-station canopy clad in polyester sheet. Its light transmission is 30 per cent - note the shadow from shading.
This appears to be the first use of polyester sheet for a petrol-station canopy. A particularly testing application for glazing, it suggests the grim inevitability of the normal canopy is not so inevitable after all.
PROPERTIES OF HOECHST HOSTAGLAS
Amorphous PET (polyethylene terephthalate) was discovered in 1941. It is used, for example, for Trevira fibres, aircraft windows and plastic bottles. Hostaglas has been available as extruded sheet since 1995
In fire, Hostaglas sheet without flame retardant additives has:
low flammability - slight, non-toxic smoke development in fire - self-extinguishing drips
Flammability rated 'B1' when tested to DIN 4102, and '1Y' to BS 476: Part 7
Working temperature range -40degreesC to +65degreesC
Options of cold bending (radius 120 x sheet thickness in mm), warm bending and thermoforming
Thermal conductivity 0.22W/mK UVstabilised High chemical resistance
Density 1.34g/cm 3(about half that of glass )
Maximum dimensions as 6mm sheet - 12 x 1.56m
Hostaglas WS (weather-stable) colourless transparent sheet has a 10-year guarantee against yellowing, loss of transparency and loss of stiffness
Contact Hoechst UK, tel: 0990 134750