I'm considering buidling a pergola off the back of our house, however, the wall I want to attach to also has the exhaust thimble from a direct vent gas fireplace, about 5 feet below where the pergola rafters would be.
Planning to use pressure treated pine. Using 2x6s extending from the house, spaced 18" apart as the pergola "roof," with crossing rafters 18" apart, paralleling the house wall. As it is now, the design calls for a 2x6 rafter to attach directly above the exhaust thimble. This seems ill advised, though I can't find any info on the web about recommended distances, etc, for such a situation. Any recommendations on horizontal clearance around where the fireplace exhaust will rise? Should I redesign to avoid the exhaust altogether?