DEAR HOME SEWING EXPERTS,

I AM MAKING DRAPES OF SUNBRELLA FURNITURE FABRIC TO HANG WITH TIEBACKS ON AN OUTSIDE PATIO. I FOUND LARGE PLASTIC GROMMETS 4 INCHES IN DIAMETER IN THE SAILRITE CATALOG AND WANT TO USE THEM TO GO OVER A 2 INCH DRAPERY ROD.THE WALL LENGTH IS TWELVE FEET ON THE PATIO. HOW FAR APART TO I PUT THE GROMMETS IN A SPAN OF 12 FEET. I AM GOING BY THE RULE OF 1 AND 1/2 LENGTHS OF FABRIC AT A MINIMUM TO CLOSE OVER THE SPACE.

THANKS IN ADVANCE.