Question: First let me say that you have an excellent website that is very informative. Now for my question. We have an existing fireplace that was used with a coal insert be the previous owners. We removed the coal insert and found several of the bricks in the fireplace loose and also the fire box was separated from the masonry by about 1.5 inches. We want to redo the masonry anyhow,and install gas logs, however when the mason came by he indicated that the chimney was starting to separate from the house and would have to come down and be rebuilt if we wanted a vented system. He also thought there were some new gas logs on the market where you could just vent out of the wall without a chimney..Is there any such thing as a system that can just be vented out of the wall or do we need to tear down our old chimney and rebuild it(involving carpenters, mason, and gas log people. Do you have a ball park for how expensive this total re built would be if can not just vent out the side of the house. Appreciate any feedback you can provide.New chimney would have to clear two stories. Answer: First of all, whether the chimney has to be torn down and completely rebuilt may be an open question. It must be determined if the separation is continuing or if it has already settled. If the chimney is intact, then simply patching up the masonry inside may result in a usable fireplaces, especially with vented gas logs...which put very low temperature gases up the chimney.I know a local contractor here who can actually jack up chimneys which are leaning! He digs under the foundation and uses railroad jacks, then pours more concrete around it. Still quite expensive. But let's explore another option. You could use a vented gas fireplace Insert. These could vent in numerous ways, from right thru the masonry behind the fireplace to a complete lining (with aluminum) of the existing chimney. These produce much more heat and efficiency than a regular gas log. It would also be safe with a separating fireplace like yours...given some small patching before the installation.