Building a new house this summer and want to make sure I know what I am talking about in case I need to intervene if the installer puts in the chimney the wrong way or tries to add a short cut. Sorry to doubt the many great installers on this site but the industry is full of poorly trained people and building inspectors in my opinion are not much better. Some sort of EPA Phase II certified fireplace will be install along an interior wall in the great room with 18' ceiling. A Selkirk or like product insulated class A chimney will be used as well. The ceiling will be framed using scissor trusses but the insulation will be open cell spray foam on the underside of the roof creating whats called a hot roof. The flue pipe will be enclosed in a chase up to the ceiling. So now this is where it gets interesting. What is the best way to go through the ceiling and then out the roof trying to maintain a very tight building shell around any penetration leading to the outside? I was thinking about putting a ceiling into the chase at the same height as the rest of the great room and then continuing the chase all the way up and out through the roof. The interior walls of the chase from the ceiling to the roof would be sheet rocked inside the chase and spray foamed from the attic side maintaining the sealed envelope and then use a product like an Attic Insulation Shield from Selkirk to make the penetration through the ceiling in the chase and use SUSI shielding insulation to help make it as airtight as possible and then insulate with bats the top of the ceiling inside the chase being careful to not be any deeper than the attic shield allows. The rest of the install above that is like a typical chase top. Overkill?