Fire officials are investigating what caused a vacant Stratford home to go up in flames.Firefighters were called to a home on 3rd Avenue off of Shoreline Drive around 5:45 p.m. Friday. Fire officials say it took them nearly an hour to contain the flames they believe sparked in a crawl space and spread quickly through the walls. Firefighters were forced to break windows and ax walls of the newly renovated beach house, which was recently put up for sale.Fire officials say the owner of the home had been at the house earlier that night and fixed a water pipe using a torch flame. They say he may have accidentally lit some of the insulation, which could have later sparked a flame. They determined the structure is sound, but say there is extensive interior damage. Neighbors say they realize this story could have had a different ending and are thankful that no one was injured.