Ok...I think I've pretty much nailed down hearth size for my unit with maintaining a required 18 inches to the front & 9 inches to the back corners of the stove. It puts the point of a 4'X4' sheet of plywood right at the 18 inches in front. Ok...so decided that I need to extend that plywood out a little. I'm thinking 2 pieces now. How do you hold them together? Or is this where a guy builds a raised hearth and than attach plywood to it? My stove is 24"X24". Thanx Jeff