I purchased my home and with it came a converted gas log set in an old 80's wood burning Mark 123 Heatilator 3138EP I recently replaced the gas logs and burner due to a slight gas leak in the pilot valve on and off switch. My question is the following. Can I install cement board over the black metal surround and attach marble? Since this is no longer a wood burning insert and the old heatilator vents are disconnected am i able to cover the bottom vent? It leaks so much cold air from the outside.