The problem is more to do with wind and flames. It is quite amazing how far a flame can travel, and how flammable some of your equipment is - for instance you may use a tea towel when you are grilling.
not entirely sure i understand what you mean about using a tea-towel. Wind is thankfully not an issue, as my terrace is in the back of my flat, and while it's open tot he sky it's protected by walls and buildings on all sides. When we eat out there we don't even worry about paper napkins blowing away.
to clarify, I'm trying to add some protection to the only flammable substance within ~8 feet, which is the wooden deck the grill is sitting on. The railing is metal, the side of hte house is brick (and ~8 feet away).