I got a call to bid an apartment building where someone had crashed into the Gas Mains and meters and caught the building on fire. The fire burned up 2 of the ten units and damaged the other 8. I was told to give the owner 2 prices one to repipe the whole complex and one to just fix what is damaged. They said they are worried about the plumbing in the walls cause smoke was coming out where the copper supplys are in 6 of the units. I am a little overwhelmed as no one can find as built plans on these units and all I can see in the ceiling is the gas mains from one unit that was burned up. Any advice on how to proceed?