I am in the process of drawing a set of plans for a new house and had a question about the surrounding construction and how it may relate to possible overfiring. The plan is for a Hearthstone Mansfield in an half alcove set up. The idea was to construct a surround of 6" CMU, grout filled and doweled to the slab on grade, and a angled solid concrete top. The set up would look like a large Rumford fireplace with a woodstove in it. With all clearances to combustables maintained by use of masonry, should I worry about overfiring due to heat build up of the thermal mass?