Terra Cotta Top Plate in-place of Extend-a-Cap for a Duraliner Install: feasible?

[Sakuji]

Hi there..

As I'm usually hesitant on making new threads to ask questions and do try to look for possible posted answers to my questions (which are usually have been answered already) before making a new one. But on this issue I really can't find the answer.

As for background, here's my intro post:

Sakuji's Planned Install
- BK Princess Insert: already paid/waiting for delivery.
- Duraliner Combo: after considering all factors we concluded (hopefully correct) that this is the appropriate liner system to use on our set-up.

As I'm in the process of making a list and about to order the needed stuff for the Duraliner, I got stumped by this simple issue: Top Plate.

My chimney top is similar to this
But without the furnace vent. The top 13 x 13 clay flue extends vertically 8" (yes 8") inches above the crown and based on these discussions: 1 and 2 (plus a couple more), just silicone sealant and perhaps 90' folding of the lips has been done and found adequate for the Extend-a-Cap kit. Fact is that is the manufacturer's recommendation and also said that if feasible anchor bolting of the plate down to the crown which in my case is not.

However, just for the sake of discussion, is it feasible for me to use a Terra Cotta top plate instead and a cap like this in place of the Extend-a-Cap? Both of those can come at various diameters that may fit the top portion of the Rigid Pipe. The reason I'm asking this is because I think that the Terra Cotta Top Plate is the right design call when terminating on a vertically extended clay. As far as I can recall Duravent have not mentioned the removal or cut-flushing of an extended clay flue. It just mentioned the bolting of the plate + silicone. However, certain manufacturers also gives us the specific option of a Terra Cotta top plate which has those side facing pressure bolts to hold unto the flue which is I think is the better design call for these set-ups.

So far the only mods that I see from the standard Extend-a-Cap is that instead of a three point screw to hold the cap it will be a clamp instead. The storm collar and the rest of the plate will be replaced by the integrated terra cotta plate. What you think, guys?

Of course these are just the musings of a totally green horn with zero liner install experience. Or somebody did this already (which is more likely). Any feedback is appreciated.

Thanks.

 

[bholler]

Persoanally i usually just take the clay down flush and mount the top plate to the crown. But as long as you buy all duraliner parts you can do it with a top plate like that

 

[Sakuji]

Persoanally i usually just take the clay down flush and mount the top plate to the crown. But as long as you buy all duraliner parts you can do it with a top plate like that

Thanks Bholler.

I actually agree with your assessment coz the way I see Duravent's design thinking at the Extend-a-Cap, the plate is really meant to be installed flushed over the crown itself. The thing is the whole top of the chimney involved is in very tip-top shape particularly all the clay flues. Even the chimney sweep I consulted recommended against shaving the top flue specially since- he said- that the clay flue may be too delicate now due to old age and can easily crack. However, being that this is my first install I personally would like to do it within design specs as far as I can even if it calls for shaving that top flue.

Which leads me to this question Bholler: how would you personally do the shaving of clay down flushed to the crown while minimizing possibility of a crack? We will really take this into consideration coz this is one of the paths I'd like to take.

On this quote:

as long as you buy all duraliner parts you can do it with a top plate like that

, do you mean if doing it with a terra cotta style plate is should be done with a Duraliner branded terra cotta plate? As far as I can recall (of course I can be wrong), there is none like that under the Duraliner line.

Anyway, I'm hoping for more feedback/ideas from you and the other guys.

Thanks, again.

 

[Heatsource]

i prefer to add a duratech anchor plate, and do any extensions with class a duratech

 

[Sakuji]

i prefer to add a duratech anchor plate, and do any extensions with class a duratech

Thanks Heatsource.
Will take that in close consideration. Though by the looks of it we don't need to add any Class A since my working liner length from collar to flue tip is 17 ft with 15 ft being the recommended length on the BK Princess insert.

Thanks so much.

 

[Heatsource]

i'm sorry i thought you were talking about extending the chimney height...

 

[begreen]

I like the terra cotta top plate. My preference is for the folded lip and anchor screws that the TC plate affords. As long as it is sized correctly to the liner it should work. I might put in a 3 screws or pop-rivets at the top to reinforce support of the liner.

 

[bholler]

As long as it is sized correctly to the liner it should work.

the problem is that duraliner is larger than a standard liner so i don't think anything else will fit right

 

[Sakuji]

i'm sorry i thought you were talking about extending the chimney height...

No worries.

 

[Sakuji]

the problem is that duraliner is larger than a standard liner so i don't think anything else will fit right

Both the TC top plate and cap that I Iinked can come with ID of 3" to 11" with 6.5" and 7" as possible options: top plate, cap.
Thing is I just passed this afternoon at the chimney shop near me. Fortunately, they are also a dealer of woodlanddirect sourced products and I was able to check out this particular models. However, they only stock the 6" and 8". The manager was kind enough to allow me measure the actual ID on the 6" which is actually more of 6 1/4". So I surmised the 6.5" can possibly accommodate the upper part of the Duraliner Rigid pipe. So I ordered a set for 119 bucks for plate and cap. Not bad.

I like the terra cotta top plate. My preference is for the folded lip and anchor screws that the TC plate affords. As long as it is sized correctly to the liner it should work. I might put in a 3 screws or pop-rivets at the top to reinforce support of the liner.

I kinda like it too and am really rooting for it to work. As mentioned, I already ordered a set @ ID of 6.5". With only 15% restocking fee and less shipping fee, I decided it's an affordable risk to take as I can always just use the Extend-a-Cap in case it won't work. I promise to post the install either way.

I actually agree with screws/ rivets up top as reinforcement. And once that is done- just for comparison's sake- I see the TC top plate as a more secure platform compared to the other coz on the Extend-a-Cap the rigid pipe is actually just floating on top of the plate. I understand that the additional horizontal and vertical security that the TC top plate will prospectively provide may not really make that much difference, I still think that it is a more "elegant" install compared to the other. We will soon find out.

Here's a guy who planned to use the TC plate on a Duraliner Install: link but upon review of all his install/ postings he didn't mentioned anywhere his final set up. He's not been active for a while and I can't find the PM link.

Will keep everybody posted.

 

[Jo191145]

Bholler will know much better than I what liner will fit your top cap.

As far as your flue is concerned one question needs to be answered. Is it in good enough condition to last the life of the liner exposed? You mentioned the sweep thought it was old enough to crack if chopped down hence my question.
In reality it matters not at all if it cracks. The liner is your new flue and by chopping it down you have altered it from its original form and use. To switch back to a liner less masonry chimney it would need to be replaced anyway.

Some liner installs remove all the flues from a chimney. As a mason I'm not really fond of that idea but it seems to be accepted practice. If the chimney was constructed properly and the liner installed correctly all should be good. I've been in construction long enough to know things aren't always done correctly.
And then there's the possibility of the next homeowner not wanting a liner/ stove etc etc. and they remove that liner. Now you have a chimney with no flues and no liner. What happens if someone decides to use that chimney? There are a lot of homeowners who think just because it's there it must be safe.
The above paragraph is irrelevant to you as your just considering making the flue flush. Just a little rant of mine and to pound home the idea cracking that top flue is meaningless. Let it crack, I doubt it will though.

I like the top cap you wish to use just because it looks finished as is. I wouldn't even use the screws provided to clamp into the flue. They can crack a weakend flue. Just caulk it down like a normal install. No idea what the pros use but GE 50 year clear silicone is the best caulk I know of. Holds up to Mother Nature extremely well with strong bond but not so strong that it cannot be removed some day if need be.

 

[Sakuji]

Bholler will know much better than I what liner will fit your top cap.

As far as your flue is concerned one question needs to be answered. Is it in good enough condition to last the life of the liner exposed? You mentioned the sweep thought it was old enough to crack if chopped down hence my question.
In reality it matters not at all if it cracks. The liner is your new flue and by chopping it down you have altered it from its original form and use. To switch back to a liner less masonry chimney it would need to be replaced anyway.

Some liner installs remove all the flues from a chimney. As a mason I'm not really fond of that idea but it seems to be accepted practice. If the chimney was constructed properly and the liner installed correctly all should be good. I've been in construction long enough to know things aren't always done correctly.
And then there's the possibility of the next homeowner not wanting a liner/ stove etc etc. and they remove that liner. Now you have a chimney with no flues and no liner. What happens if someone decides to use that chimney? There are a lot of homeowners who think just because it's there it must be safe.
The above paragraph is irrelevant to you as your just considering making the flue flush. Just a little rant of mine and to pound home the idea cracking that top flue is meaningless. Let it crack, I doubt it will though.

I like the top cap you wish to use just because it looks finished as is. I wouldn't even use the screws provided to clamp into the flue. They can crack a weakend flue. Just caulk it down like a normal install. No idea what the pros use but GE 50 year clear silicone is the best caulk I know of. Holds up to Mother Nature extremely well with strong bond but not so strong that it cannot be removed some day if need be.

Thanks for the feedback, man. All very good points. I appreciate it.
Though just to be clear, I'm not planning on cutting the flue flushed hence the use of the terra cotta top plate.
Funny thing is since you mentioned that GE 50 year silicone. Last spring I had my aboveground full deck upgraded to 25 year vinyl decking, the man who fixed it said exactly the same thing to me about this particular silicone. That's why I have a couple of extra unopened tubes somewhere in my shed out back. Thanks for the ideas.

 

[bholler]

Some liner installs remove all the flues from a chimney. As a mason I'm not really fond of that idea but it seems to be accepted practice.

That really is only done when it is required for clearance. And usually not on a fireplace. When it is done n a fireplace you must tag the chimney with a label stating that it cannot be used as an open fireplace without repair.

The above paragraph is irrelevant to you as your just considering making the flue flush. Just a little rant of mine and to pound home the idea cracking that top flue is meaningless. Let it crack, I doubt it will though.

I agree if it is deteriorated like the sweep said it makes no difference if it cracks or not it is not usable anyway. It is also easy to replace the top tile if you ever want to go back. I see not problem at all using the terracotta top plate as long as it fits the duraliner and supports it well enough. I just think taking the liner down flush makes for a much more professional looking install which is why i do it usually

 

[Sakuji]

That really is only done when it is required for clearance. And usually not on a fireplace. When it is done n a fireplace you must tag the chimney with a label stating that it cannot be used as an open fireplace without repair.

Bholler

Can you link a pic of this tag you mentioned about modded fireplaces. It's not that I'm already selling my house. Har har. I believe, modding the damper section and such will also require this. I just can't seem to find one by googling.

Thanks

I just think taking the liner down flush makes for a much more professional looking install which is why i do it usually

Nailed it on the head. Part of me wanted to this but since it's the first build I've been trying to be conservative as long as it's within spec. Perhaps I'll do this on the second chimney since its crown already got surface cracks on it that only got siliconed by the previous owner prior to selling.

 

[begreen]

This is from the interwebs.

 

[Sakuji]

This is from the interwebs.
View attachment 166107

Nice.
Thanks Mod!

And what do we call this exactly? Will try ebaying it.

 

[bholler]

And what do we call this exactly? Will try ebaying it.

They usually come with the insert. But we also have some we got from some supplier as well

 

[Sakuji]

They usually come with the insert. But we also have some we got from some supplier as well

They do? Nice.

Will keep you guys posted. Most of the stuff for the install has been ordered. Will start cleaning/ modding the fireplace area in the coming days.