I have a 60 year old home with an existing wood burning fireplace that I installed a gas insert in. The exterior chimney is constructed of stone on a concrete block foundation with a concrete footing. The interior around the fire box opening in my living room is also stone. My problem is that directly below the fireplace in the basement, the basement wall is damp and the block is scaling with a great deal of efflorescence. It seems like it has been doing this for many years. At the concrete floor where the block wall meets the floor I am getting water seepage. I am assuming the interior of the chimney itself is sweating, running down the inside of the block wall causing the wall dampness and water pooling on the interior concrete floor. This is only a guess as I am not familiar with the interior cross-section of the chimney. Without removing some concrete block from the basement wall I'm not sure whats going on. If it is being caused by sweating could I vent the chimney block foundation similar to venting of a cold storage. Drill a hole through the exterior block and cover with a vent? Any feedback is greatly appreciated.