Mortar Cap or Not??

[Jengah]

I have a 20" X24" brick chimney with a 10" terracotta insert built in 1973. I'm going to be installing a 6" liner into it which will mate up with a Regency I1100. I need help with how to finish off the top. The existing terracotta liner is flush with the bricks. It seems there used to be a mortar cap, but it has since fallen apart.
Thus, I am left with a flat top chimney. I will be removing the vertical bricks that you see holding up the failing top cap. The house in the mountains so I am concerned about snow sitting up there and melting. I'm in California, so I know I need to install a 5/8" mesh cap, but need help on what to do for the base.


My question is, should I
a.) use the standard 12"X12" SS chimney cap that comes with most insert kits and just screw it down with a bead of sealant, OR
b.) use the same chimney cap described above, but then add a mortar cap to it so the water/snow runs off, OR
c.) get a 20"X24" SS chimney chase cover and cover the whole top?

Expense is a bit of an issue, but so is timing. I have been without heat this winter and want to get my new insert installed and working.

 

[Nick Mystic]

If you could take a photo of how the clay tile flue is situated inside your brick chimney we can probably give you more accurate recommendations. I think some of your descriptors aren't accurate terminology. When you say you have "10" terracotta insert" are you referring to the size of the clay tile flue inside the chimney? If so, is there a second flue inside the 20"x24" brick chimney or just the single flue? If it is just the one 10" clay tile flue liner, then can you tell us how it is held in place inside the brick chimney" Is there a large gap showing between the clay liner and the insides of the brick chimney?

I think a top plate that completely covers the clay flue will be sufficient so long as it can be get a good seal with some silicone caulk. There isn't even any need to screw it down since the weight of the flex liner will pull it down tight to the top of the clay tile liner and the silicone caulk should secure it in place. However, you also need to seal up the remainder of the chimney opening so that rain/snow cannot get down your chimney between the clay tile liner and the brick chimney. If that is already sealed in some way then you should be good to go. If it isn't, then you will need to fabricate something that can accomplish this.

 

[Hogwildz]

Leave it as is and end the liner with new cap under the stone on top.
You can use a top plate at the top of the main chimney bricks to seal off and terminate the liner connection.

 

[bholler]

Leave it as is and end the liner with new cap under the stone on top.
You can use a top plate at the top of the main chimney bricks to seal off and terminate the liner connection.

Problem with that is the top is falling apart. I would remove the top and the brick pillars. Then i would either pour an overhanging crown or do a full stainless top cover.

 

[cableman]

I would do full stainless. Im gonna do it to my boiler chimney also. This is 18 gauge i believe.

 

[Jengah]

If you could take a photo of how the clay tile flue is situated inside your brick chimney we can probably give you more accurate recommendations. I think some of your descriptors aren't accurate terminology. When you say you have "10" terracotta insert" are you referring to the size of the clay tile flue inside the chimney? If so, is there a second flue inside the 20"x24" brick chimney or just the single flue? If it is just the one 10" clay tile flue liner, then can you tell us how it is held in place inside the brick chimney" Is there a large gap showing between the clay liner and the insides of the brick chimney?

I think a top plate that completely covers the clay flue will be sufficient so long as it can be get a good seal with some silicone caulk. There isn't even any need to screw it down since the weight of the flex liner will pull it down tight to the top of the clay tile liner and the silicone caulk should secure it in place. However, you also need to seal up the remainder of the chimney opening so that rain/snow cannot get down your chimney between the clay tile liner and the brick chimney. If that is already sealed in some way then you should be good to go. If it isn't, then you will need to fabricate something that can accomplish this.

Hi Nick - thanks for the post. Sorry if some of my descriptions is screwy, I'm new at this.

Yes, I have a 10"X10" clay tile flue inside of the chimney.
No, there is no other flue liner, just the one. I'm really not sure how it is held in place because the top is filled in around it. In other-words, no, there is not a gap surrounding it.

Thanks

 

[Jengah]

Problem with that is the top is falling apart. I would remove the top and the brick pillars. Then i would either pour an overhanging crown or do a full stainless top cover.

You got the "falling apart" part correct. What you see in the picture is actually just a metal plate and some slate tiles propped on top of the tall bricks. One more brick has already come off, I just need to remove the other three.

I saw one video where a guy used the standard 12"x12" top cape with plate, mounted that, then poured a mortar cap on top of that. Is that what you are referring to?

 

[Jengah]

I would do full stainless. Im gonna do it to my boiler chimney also. This is 18 gauge i believe.View attachment 173700

Thanks - I'm strongly considering it.

 

[bholler]

I saw one video where a guy used the standard 12"x12" top cape with plate, mounted that, then poured a mortar cap on top of that. Is that what you are referring to?

No you should not use mortar to start and it should not go over the top plate. It should be concrete have a bond break between the top of the chimney and that crown it should over hang the existing chimney by about 1.5". Search for poured concrete crown you should get some info. But a full stainless plate with the edges bent down around the top it a good solution also.