We have a real flame gas fire fitted in our living room, which we love and use occasionally. However, the problem is there is always a cold draught coming down the chimney making the room cold even when the central heating is on. Looking closer, the gap at the top of the gas fire into the chimney is large as some of the black fireproof backing (brick effect) has been cut away. Is it possible to buy this black fireproof backing anywhere, so I can add a piece to close the gap. If so where and what is it called. What is the minimum gap I should leave to allow the gas out, but reduce the draught in. Any help would be appreciated. Kevin. 
