A contractor working on tile inside a home in the 200 block of Doone Road in the Fairless Hills section of Falls Township was alerted to a fire by a knocking sound Tuesday night, officials said.

The sound, which may have saved the contractor's life, was made by a fast-moving fire that started outside the house and quickly spread into the attic, Fire Marshal Rich Dippolito said.

The home was in the final stages of being renovated and a family was expected to settle in the house in a few days time, Dippolito said.

The fire marshal said he is still investigating what caused the fire. However, it was determined the fire emanated from a pile of construction debris outside.

Emergency crews arrived to the house to find flames shooting out of the roof, Dippolito told Patch.

As firefighters began to leave the scene, yellow insulation could be scene hanging from the ceiling of the fire-wrecked house.

Crews from Fairless Hills, Falls, Levittown No. 2 and William Penn fire companies responded when the call went out just before 7 p.m. Levittown-Fairless Hills Rescue Squad also responded.