Grate Accumulation is a term used to describe the buildup of ash that can occur in a fireplace or wood stove. This buildup can be caused by burning wood that is not completely dry, or by burning wood that has been treated with chemicals. The ash can be difficult to remove and can cause blockages in the chimney or flue. The term 'Grate Accumulation' is used to describe the buildup of ash that can occur in a fireplace or wood stove.