Install Chimney Liner to Prevent Crumbling Brick

Oldfarmhouseprobs asks,

I live in an old farmhouse in Virginia built in 1900. I am having spalling with my bricks (coming from a chimney used for a 10-year-old boiler) and have been told by a company that the water damage on my ceiling and continued spalling on the chimney is due to the gaps/damage on the bricks. The company has recommended that I put a wire mesh around the chimney because they said it is in decent condition (liner and cap still okay) and to stucco it. I don't want stucco. Could I put brick veneers on instead, and would the roof be able to hold this weight since the chimney is only exposed above the first floor? Is there another solution that you recommend? Any help would be greatly appreciated. Thank you. Sincerely, Page Hyler

Our Answer

The reason the chimney is falling apart is because it’s very old, and very likely not lined if it was put in in the 1900s. What has made your problem worse is your 10-year-old, probably standard efficiency gas boiler.

Exhaust gas is 80% water vapor and very acidic. It condenses as it goes up through the chimney and deteriorates the brick because the bricks get wet, and then the water freezes and causes cracks.

I would recommend a stainless steel chimney liner. It can be dropped from the chimney down through to the boiler. The liner is like a flex duct: It expands like a slinky and stretches out. It’s connected to the boiler on one end and the top of the chimney on the other, and all the exhaust gas is passed up through the liner.

Once the liner is in place, then the bricks can be repaired from the outside and the mortar can be replaced. But don’t repair the chimney until a proper liner for gas appliances is installed.