This building’s roof had ballast rock for days. This large senior care facility was meant for Duro-Last. A hundred penetrations dotted this roof but with the help of Duro-Last prefabricated roof flashings and stacks Grell Roofing made short work of a 20,000-square foot facility. No glues or adhesives were needed. A hot air welder and skilled roofers can make a job look amazing.