Date:26 November 2012
Q We have a nice old house with an obvious flaw: the chimney curves. One contractor told us to brace the chimney and convert the home’s heating system to a more modern type that vents through the sidewall, not through the chimney flue. Taking the chimney out of use seems extreme, as one of its flues serves a fireplace that we use. Others say we should rebuild the curved section, and still others advise installing a stainless-steel liner. What’s the best remedy?
A Chimneys lean for a variety of reasons. Weather erodes the mortar joints between the bricks, a TV antenna (remember those?) catches wind and stresses the masonry, and sulpurous chemicals from coal fires attack the mortar and the flue; the latter is especially likely if the chimney lacks a ceramic flue liner.
Regardless of what put a kink in your chimney, I’m sorry to say that I don’t have a single answer to the problem.
Your best bet is to have the structure inspected inside and out by an experienced chimney sweep (yes, these people still exist); this is done with a small camera attached to fibre optic cable. Once you’re armed with the inspection report, you can pick the best solution. Having a builder restore the chimney is appealing because it would preserve the house’s architecture, but it’s not a complete fix – more about that in a moment. The procedure, though, is pretty straightforward: the builder takes the chimney apart right down to the roof flashing and then rebuilds it, complete with new flashing.
Because rebuilding the section above the roofline does nothing to address hidden problems such as a crumbling flue, you may need a combination of solutions that take into account both the repair above the roof and the condition of the flue. You might consider putting in a stainless-steel lining, but this could prove expensive.
Glossary: Smoke shelf
A smoke shelf is not a mythical device such as a board stretcher. It’s a flat projection above the throat of the fireplace, right behind the damper, so it’s out of plain sight. It prevents a downdraft from travelling through the firebox.