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					Originally Posted by Ducay  The mechanical is below the kitchen area, but there is also another interior wall that forms part of the kitchen that is much thicker. The only venting near/on the wall itself looks like a cold air return on the wall at floor level. | 
	
 
Firstly, is it a bungalow or 2 storey? secondly, how old is the house?
once you're there, things get easier. Typically, in most homes, even old ones, 4" walls usually are only partician walls. the wider wall you spoke of, is most likely where the flu's for your main drain, and the furnace flue. if it is a bungalow, or under one storey of a split level, the trusses will span the entire width of the room, and the 6" outside wall being load bearing.
 Getting to the drawings, most design firms have an architectural tech on hand to draw up most of the stuff you would need to get a building permit. they will ultimately be able to let you know what is what, and if it is indeed a bearing wall, they will be able to give you solutions as to how to do what you want in a different manner. ( i used to desing homes and do this sort of stuff in canmore)