I used 1/4 inch Durarock cement board to provide a fire block on the ceiling above the stove, and on a wall located about 48 inches in front of the stove. I noticed when I picked these boards up, they had an odor, chemical like. Thinking it would disappear, I installed it as planned. Now after heating the stove up a few times, the odor becomes unbearable and literally pushes us out of the house. I have used similar board before and have no recollection of such an odor. I had installed a second board that is different, above the stove with a spacer to allow heat disapation at that critical point. That board is backer board, and is light in color. It has no odor at all. I will be returning to the Depot to make a "stink" (pun intended) about this board. Bottom line, I wouid not use the gray cement board if you are doing something similar. Stay with the lighter backer board (found in Lowes).