We are having our dining room decorated. There was an awful 1960s gas fire that we disconnected and removed the fake brick surround, behind this there is an old coal fire that is badly damaged and the brick work needs work too. To save cash we have decided just to build a frame and board over the whole lot, this is about 4 inches deep away from the breast. The top of the stack is sound as we had it repointed and reflashed 2 years ago and I assume the cowl is ok, so do we need to vent the stud wall in the dining room?