Terminating top of new insulated rigid liner in an unlined brick chimney

[sean_999]

I'm considering having a new stove installed, with a new insulated rigid liner (installer proposes 6" DuraLiner) to be installed in an unlined brick chimney with one large flue: 8" x 20" (yes, that's interior flue dimensions: house built in 1910). Height is short, about 13' from stove exit to very top. There is no crown at all, just a top "soldier course" of vertical bricks. (If there was ever a mortar or concrete crown on top of those, there is no evidence of that now.)

As I said, this is an unlined chimney (no clay flue tile at all), but the installer asked me to have a mason install a concrete crown (which makes sense) AND a single 12x12 clay flue tile at the top. This huge flue tile seems a bit excessive to me (and I think it will also look a bit ridiculous). I'm seeking clarification from the seller/installer, but thought I'd check with folks here about what is recommended for my situation.

1. Does it really make sense to install this big clay flue tile at the top of an unlined chimney?
2. The installer's estimate includes a Duraliner 6" 13" X 18" Extend-a-Cap Kit, at nearly $400. Is that the best way to go here?
3. Can whatever top plate is used with the rigid Duraliner sit directly on a new concrete crown? From comments in an earlier thread (https://www.hearth.com/talk/threads...nce-fabricate-an-new-top-cap-and-more.192882/), I gather that the answer is 'yes'.

I'll post a couple of photos of the chimney. (As you can see, it also needs lots of tuckpointing.)

Thanks for any comments or suggestions!
-Sean

 

[begreen]

What stove is going in? Many Canadian stoves will work on a 13' flue, especially if insulated. Another option, in that case, might be a custom stainless cap.

 

[sean_999]

What stove is going in? Many Canadian stoves will work on a 13' flue, especially if insulated. Another option, in that case, might be a custom stainless cap.

Sorry for not mentioning. We're planning on a Morso 7110, which (according to Morso) needs a chimney height of 4 meters (just over 13 feet) from stove termination.

In case it matters, we'd like a stove mostly for ambiance and some evening extra warmth (and for emergency heat if electric power is out during heating season -- we're in Seattle).

 

[begreen]

I would try it with the 13' insulated liner. The Morso 2110 I helped install has a less ideal situation and it drafts ok as long as you don't try to reload when the wood is in the outgassing (smoky) stage. Your installation will probably draft ok when outside temps are 45º or below.

 

[sean_999]

I would try it with the 13' insulated liner. The Morso 2110 I helped install has a less ideal situation and it drafts ok as long as you don't try to reload when the wood is in the outgassing (smoky) stage. Your installation will probably draft ok when outside temps are 45º or below.

Thanks for the reassurance on that, begreen.

What do you think about the installer's idea of having mason install a 12x12 clay flue tile above the new concrete crown? Installer (not the mason) says that having this flue tile "will give you the best long term weather seal".

 

[bholler]

Thanks for the reassurance on that, begreen.

What do you think about the installer's idea of having mason install a 12x12 clay flue tile above the new concrete crown? Installer (not the mason) says that having this flue tile "will give you the best long term weather seal".

A clay tile at the top makes no sense at all. You need either a poured crown or a stainless chase cover. Is the chimney currently 2' higher than anything within 10'?

 

[begreen]

A properly done stainless chase cover will probably be the lowest maintenance over time. It looks like the top bricks should be repointed first. The cap can be ordered online or there are good sheetmetal shops in Seattle that can make it up out of stainless. I have had stainless work done by both Ballard Sheet Metal and Pacific Sheet Metal in the past.

Is the chimney currently 2' higher than anything within 10'?

Thanks for asking that. It's hard to tell from the camera angle.

 

[sean_999]

A properly done stainless chase cover will probably be the lowest maintenance over time. It looks like the top bricks should be repointed first. The cap can be ordered online or there are good sheetmetal shops in Seattle that can make it up out of stainless. I have had stainless work done by both Ballard Sheet Metal and Pacific Sheet Metal in the past.

Yes, definitely needs pointing, if not more. Thanks for info on a chase cover option -- I'd wondered about that approach, mainly to avoid the weird (to me) 12x12 flue tile idea.

Thanks for asking that. It's hard to tell from the camera angle.

I'm 98% sure it is (roof pitch is fairly shallow), and a chimney sweep/mason who just finished site visit didn't mention that particular issue.

BUT the sweep/mason says that the mortar is in bad enough shape that they will only do the cast-in-place crown if the chimney is taken down to the roofline and re-built up from there. Doubles the price of whole project (stove, liner, installation of these).

FWIW, both he and the stove installer say that they like to have some clay flue tile going up above the top of the crown so that the edge of whatever metal top-plate is used can be (1) above the crown and (2) have outer edge folded down over the flue tile, all for better rain protection. This is Seattle, so maybe they're right to be so careful about that. (I'm not a native of this area, and have never been involved with chimney work, at least not since I was a kid learning to tuck-point on a 40 foot ladder.)

 

[bholler]

Yes, definitely needs pointing, if not more. Thanks for info on a chase cover option -- I'd wondered about that approach, mainly to avoid the weird (to me) 12x12 flue tile idea.

I'm 98% sure it is (roof pitch is fairly shallow), and a chimney sweep/mason who just finished site visit didn't mention that particular issue.

BUT the sweep/mason says that the mortar is in bad enough shape that they will only do the cast-in-place crown if the chimney is taken down to the roofline and re-built up from there. Doubles the price of whole project (stove, liner, installation of these).

FWIW, both he and the stove installer say that they like to have some clay flue tile going up above the top of the crown so that the edge of whatever metal top-plate is used can be (1) above the crown and (2) have outer edge folded down over the flue tile, all for better rain protection. This is Seattle, so maybe they're right to be so careful about that. (I'm not a native of this area, and have never been involved with chimney work, at least not since I was a kid learning to tuck-point on a 40 foot ladder.)

There is absolutely no reason to use a clay tile at the top in this case. It would actually introduce a weak spot for water infiltration where the clay enters the concrete crown. The chimney doesn't really look like it needs a complete rebuild from the pics but if it really is bad enough that a mason won't pour a crown it really shouldn't be lined until it's fixed