it already has a Dbl sided fire place which if removed a refigured looks like a pretty big stove could go there. Im DBL wall all way thru roof But its not tall enuff .Can I connect Non Dbl wall to thee Dbl wall after penetrating the roof ? just to get higher .. Me thinks its legal but must some kind of fitting to keep water etc from going dwn outter wall of the dbl wall when i stick reg stove pipe in the inner hole? understand maybe a picture?