Heidi J. Ellsworth road trips east to visit with Mitch Gilbert and Jason Dark of Duro-Last about the evolution of the sustainability movement in the building industry.  Known as a leader in sustainability, Duro-Last has been developing and supporting sustainable roofing systems and programs for decades.  Now a part of Holcim, the company and its leaders are helping to take the roofing industry to the next evolution of sustainability.  They share the effect on the roofing industry and how contractors can be a part of the solution.