Station 6 (Flourtown) and Station (29) dispatched on box 32-28 for the commercial building fire. Chief 6 went en-route and was advised by county that roofers were doing work on the building and the building was filling with smoke and possibly had fire in the wall.  County also advised that the alarm company was on the phone and was reporting a smoke detector activation for the building. Upon arrival Chief 6 had smoke showing from the area the roofers had been working in. Engine 6 arrived and pulled an 1-3/4 and went to open up the exterior wall. Ladder 6’s crew went to the interior to open up and check for extension in the wall. Fire was found in the wall and extinguished as the crew’s opened up. 29′ s crew assisted with ventilation and checking for extension to the 3rd floor.