I have a fireplace in the middle of my ranch house in a brick wall that sections off the living room and kitchen/dining room. Currently I am insulating the attic in attempt to at least double the r value. On either side of the fireplace there are large air spaces in between the brick. maybe 3 by 5 foot and opens into the attic. Like two more chimneys going into the attic. Am I loosing large amount of heat through the brick wall into the attic? The floor of the attic is insulated, the roof is not. I would rather not cover up the opening for fear that I will not do a proper job so that 10 years down the road some poor owner will walk on that covering and fall through and break a pair of legs if not worse. I will if I am loosing heat.