I have a restaraunt on the bottom floor of a 3 story building. I need to run my exhasut ducts to the exterior wall and up to the roof. The vertical run will be 42' +/-. the shaft will be 3' x 2' interior dimension. The exterior wall is 3 coat stucco on metal lath over building paper over densglass gold over 6" metal studs. What will be teh best design/ framing method to construct this shaft? This will be built in Florida- are there any code violations by running an exhasut shaft up an exterior wall? Where will be teh best place to find details? Thanks.