At about 3:05 PM we were dispatched to reports of a building on fire on Locey Lane. Upon arrival it was determined that the fire was on the roof, which was under construction. Parapets up to 10 feet in height around the entire building made access difficult and initially impeded firefighting efforts. A line was ultimately stretched to the roof and the fire was contained to the approximate area of origin. The investigation revealed that sparks from an operating grinder ignited insulation. Units were back in service at approximately 4 PM.