since i just did a 8,000 sq ft job and there was alot of prerfabricated trusses and alot of duct work etc to fabricate around the company i sub threw gave me 1100sq for the job i only used 1000 thats how i have extra and any extra i get i hold onto you never know when you might run across a side job. plus the company i sub threw wont sell me the material because they want to get there greedy hands on every last cent of profit.