We have a 100-year-old house with a double brick chimney, meaning there's an inner and an outer brick wall. The inner wall is reportedly in not-great, somewhat deteriorated shape. There is no clay or other lining, just a brick and mortar inner layer.
I'm wondering, could it ever be safe to use a chimney like this? It's my understanding that most of the flammable deposits that burning wood creates won't be present when using vented gas logs.
I have received three conflicting opinions by professionals, each possibly with a profit motive to be less than honest. One of the companies insisted that it would be unsafe to use the chimney without adding a modern liner, but based on evidence, they seemed to be the least trustworthy.