Nearly all high quality awning and terrace cover fabrics are water resistant to a very high level as standard. It is possible to order special water proofed fabrics.
Although it is possible to order some fabrics with a special waterproof coating it is not necessary on a normal retractable awning as the patio awning should have the pitch set to drain all rainwater as fast as possible to avoid ‘pooling’ and then allowing the water to collect and stretch the fabric. All normal wall mounted retractable awnings ideally should be set with a 14 degree pitch as a minimum so as to allow water to drain effectively. If you do not have this pitch, and the water does collect as it comes down heavier, being waterproof will not help at all as the damage will be done by the weight of the water stretching the fabric.
The only real use of waterproof fabrics is ever required on properly supported terrace cover systems such as the Gibus, Plaza and Pergola systems where the fabric is made far tighter using a ‘zipping’ system as well as being held under tension from the front bar, or where aluminium support struts are fitted across the span to help support the fabric to a level where snow loadings can be achieved.
These systems do not need to be at 14 degrees but again it is desireable if possible for effective rain water drainage.
A limited amount of fabrics can be waterproofed and the choice is limited and there are also a limited range of fire proof coated materials for use in public places or high risk areas.