Careful - the stuff listed as parachute fabric will not be as windproof as you may think, it needs to have a certain degree of permeability for the parachutes to work correctly. That is one of the reasons that the newly manufactured material gets rejected. Got that straight from a manufacturer when I went searching for the stuff myself for a project. The siliconised stuff isn't waterproof either, only water resistant because the air permeability allows the wind to blow a fine mist through the fabric.