From the web.. utracote weighs on avg.. 5g / sq ft more or less depending on color used. The pre painted fabrics like solartex are around 8-9g/sq ft. so every 3 sq ft adds just under an ounce of weight so your probaly looking at 3+ ounces additional weight for 12 sq ft of covering. I know you will need more but the 12 is what I will need and thisseems negligable for my next build considering theease and convenience. I've never used it but plan to on my next build so this is not from personal experience.