The r value has to be 1.5 so i want a 1 inch ventilated air space. i wanted to use wonderboard on top of stell studs but i dont see how .5 in wonderboard will support my stove? also, why is this stove so heavy and with such big clearances. ie 20 inches on the sides to unprotected surface. englander 2200 sq ft. timber ridge. canadian tire.