Extending a masonry chimney

[Ludlow]

Is there an adapter to join a flex liner with a section of class A? The clay lined chimney will need to be extended 3'.

 

[Blazingembers7749]

Yes there is but it doesnt look very good

 

[Blazingembers7749]

 

[Blazingembers7749]

Heres one with the adaptor you were speaking about. Is doesnt look good but its quick and easy.

 

[bholler]

Its basically a top plate. The bottom portion has a bandclamp and a collar to accept the liner and the top portion has a collar to accept the class a pipe and you screw the pipe to it. The top plate flange is very large and usually needs to be trimmed down. Its also very thick and stainless so expect to use a lennox diamond 4.5" grinder cutting wheel. I usually cut the flue tile flush to the crown splash and imbed the adaptor in mortar as well as a couple inches of the class a pipe in order to keep it from moving in the future. One of the chimney supplys may also make this adaptor as a terricotta mount with set screws but i havent used that kind. Usually connecting the liner is a little bit of a pain. Definitely helps to have two people

Why would you not just achor the plate down as it is designed and how the instructions say. I have never seen mortar over a stainless plate hold up well at all. Just follow the directions.

 

[Blazingembers7749]

I do anchor them down as well as cauk under them... The ones ive used use epoxy around the collar and can flex a bit under a wind load so i add mortar on top to help secure it. I dont think its going anywhere either way. Its just the way i do it. Ive yet to see any issues from this as it will hold hold up better than just securing it with masonry anchors.

 

[bholler]

I do anchor them down as well as cauk under them... The ones ive used use epoxy around the collar and can flex a bit under a wind load so i add mortar on top to help secure it. I dont think its going anywhere either way. Its just the way i do it. Ive yet to see any issues from this as it will hold hold up better than just securing it with masonry anchors.

Untill it cracks and directs water under your new mortar like most i have seen. Unless you go atleast 2" concrete onto of the plate it will crack.

 

[bholler]

Also if you do thick enough masonry it will be a big pain if you ever need to pull the top plate. I have been doing this long enough to know it is unwise to make things difficult to work on in the future.

 

[Blazingembers7749]

Ive yet to have one crack.... will definitely make it a pia to pull off should you for some reason need too

 

[bholler]

Ive yet to have one crack.... will definitely make it a pia to pull off should you for some reason need too

And how long have the ones you have done been in service? How thick do you go with what product?

 

[Blazingembers7749]

2 years. On that particular one everything starts below the splash. In order it goes angle iron, 2 1/2" hardie boards sandwiched together, liner to class a adaptor expoxed and anchored to the hardie board 6" class a pipe, thin layer of mortar, 1/2" hardie board to sandwich the plate to the bottom layers of hardie board. Anchors to Pull the 3 hardieboard layers together 3" section of class a pipe + diamond cap, then probably 5-6" of type s mortar.

 

[Blazingembers7749]

Typo** the class a pipe is a 6" + a 3' not 3"

 

[bholler]

2 years. On that particular one everything starts below the splash. In order it goes angle iron, 2 1/2" hardie boards sandwiched together, liner to class a adaptor expoxed and anchored to the hardie board 6" class a pipe, thin layer of mortar, 1/2" hardie board to sandwich the plate to the bottom layers of hardie board. Anchors to Pull the 3 hardieboard layers together 3" section of class a pipe + diamond cap, then probably 5-6" of type s mortar.

I am curious how you used 5-6" of mortar yet the rib on the bottom of the class a that is only about 2" up is still visible.

 

[begreen]

Moved to its own thread so that this discussion is more discoverable in the future. If folks can post pictures and descriptions of a conventional extension using a class A transition plate bolted to the chimney top that would be helpful too.

 

[Blazingembers7749]

Theres a 6" piece connected to the top plate

 

[bholler]

Theres a 6" piece connected to the top plate

If that is the case it shouldnt crack anymore than any other wash with no expansion joint around the flue.

That looks like ventis pipe if so where did you find a 6" section