I am planning to extend a half floor to become a complete floor, however this will cause it to encompass a double wall chimney pipe that is currently connected through the roof. To build this second floor I must construct a post on which will sit a primary beam, and from which two secondary beams will branch out on either side of the pipe. See diagrams below. These beams and post will be 5 1/4 x 7 1/8, and the post will reach 6 1/2' high. On average these beams have a space of 18" between them, but I have some leeway to place them differently. All members are to be from pine, including the 2x6 floor boards to be added eventually.
So, how far must everything be from these new members? I can only move the woodstove so far from the post because of a nearby door (is there shielding I can use if it is too close?), but the chimney pipe can be adjusted more freely in both directions. In the diagram I did not include the S-curve, but you can see it represented by the two pipes adjacent to each other. I live in Massachusetts in case that makes a difference.
I assume I will place some sort of apron or guard around the pipe where it goes through the 1.5" floor boards - I suppose there will be a minimum distance required here as well?