Companies got the dispatch for 1224 Whitby, fireboard advised of numerous calls. 16-9a arrived o/s reporting heavy smoke from the rear and req the r.i.t. out of station-03. Shortly after he requested the full 2nd alarm. Companies had heavy fire in the 1st floor with extension into the 2nd floor roof area. They had 3 lines stretched & operating with the truck company opening the roof.