I just got my chimney inspected with a video inspection. The house was built in 1940 and the inspection showed that the flue has clay liners that are in perfect shape (no cracks, no creosote, still orange in most places).

The only issue that the inspection showed was that the mortar joint between the clay liners had gaps, possibly from water eroding the cement (the chimney is not capped, so we will definitely be doing that).

I plan on having no more than 10 very tame aesthetic fires a year (2-logs) with very good seasoned wood (which I believe produces less creosote).

From a safety perspective, is it necessary to pay the $1500-3000 to have those cracks sealed?

Thanks for any input!

1 Answer 1


A single fire could cause health and safety issues if enough of the exhaust gases find a path into the home or heat finds its way to built-up creosote between the chimney proper and its liner.

I would question their method and service-life performance of "sealing" clay liner mortar cracks and compare that, as well as cost, to re-lining the chimney with a flexible, stainless steel flue liner (for its expansion/contraction properties --which tend to break up & drop adhering creosote-- over the rigid format). Flex liners tend to be about US $100+/ft.

  • Thanks for the answer. It's hard to properly evaluate the risks as a layperson. For instance, a doctor could say that smoking ten cigarettes a year could cause health issues. However, although there might be a statistical difference there just isn't a practical health impact (for 10/yr). Commented Jan 18, 2017 at 16:12

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