I need to build the hearth this week, I will be doing a corner hearth pad and I will be using a heat shield. With using the heat shield, it says I can reduce the corner clearance to 6". The manual says that a corner installation needs a minimum of 54"x54" hearth pad, however the diagram shows a 60" pad... I don't understand the "calculating a corner hearth pad" equation that they give. Does anyone have the exact measurements for a corner hearth pad for the ideal steel with the heat shield?