hi guys, i am needing to add two feet on my existing chimney so that its up to code. i have a metalbestos chimney pipe running through the roof and outside. I talked with a guy at a stove shop, and he told me unless i can figure out exactly what brand of pipe i currently had i might have to replace the whole chimney. he said even if i find a two foot section that may fit onto my existing chimney it wouldn't be safe if i didnt know for sure it was the same brand. can anyone out there support or deny this. thx