Bluestone chimney cap with seam?

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New Member
Dec 1, 2021
New Hampshire
Hey folks,

New here, but have been reading up on everything I can find. Thanks in advance for your advice.

A little background. I have a 2 flue brick chimney that had a fire place in one flue and (ahem) an oil furnace AND an old Thatcher coal furnace in the other flue. I've been burning wood in the coal furnace, which heats the whole house (1800 sq/ft) through a grate in the living room, but burns through cordwood like crazy. Of course, this arrangement also wasn't code. So, I decided to put a Woodstock Fireview stove in front of the fireplace and permanently disconnect the coal furnace.

My question is about the chimney cap. I had the chimney completely rebuilt from the roof up about 15 years ago. The chimney is brick and looks about like the one in this picture except it has about a 4" thick concrete cap. The mason who rebuilt the chimney used the original concrete cap. SWB with Bluestone Cap 1.html.

When the pro's came to install the stove, they were going to run a metal liner down the tile-lined fireplace flue, but said that to do this they needed to cut a hole in the existing concrete cap. Unfortunately, it didn't go well. They said that the concrete had just an "X" of rebar through it with the middle of the "X" right where they cut, causing the concrete cap to collapse. They then decided to replace the cap with a bluestone cap. That all seemed good to me, but when they were done, I realized that they'd cut the bluestone cap in half. When questioned, they said that the bluestone was too heavy to get up to the roof, and that they'd cut it to get the two pieces up and then sealed it back together with silicone.

Somehow, this doesn't seem like a great idea to me, that is, having the solid one piece chimney cap end up being replaced with two pieces of bluestone siliconed together, but maybe this is OK? Really appreciate your input. Many thanks!


Burning Hunk
Oct 25, 2019
I have an old bluestone cap in two pieces. Better than concrete. They are right about the weight. IMO no problem. Over the years maybe the silicone will need a new bead on top.

Bad LP

Minister of Fire
Nov 28, 2014
Northern Maine
Nothing to worry providing they got a good bead of sealant thru the full thickness of the cap.

I’ll bet it looks better than the concrete too!!!


New Member
Dec 1, 2021
New Hampshire
Great! Thanks for reassurance re: the two piece cap. I'll make sure the sweep checks the seal during chimney cleaning.
And, yeah, the bluestone looks sweet!
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