Outdoor Fireplace Chimney Extension

[rustlerski]

I have a brick outdoor fireplace built against an exterior wall of my house. The chimney will need to be extended up about 12' due to a second floor addition. I'd rather not add more brick so thinking some sort of class A extension is best. The fireplace get's used a few times a year.

The chimney is unlined and there is no damper. The firebox is 38"x32" and the flue dimensions are 7.5"x25.5"

In browsing the site I think I understand the best way to do this is to add a line with block out place, use an adapter at the top, and use Class A with support going up from there. Is this the best way to do this or are there other methods that will work?

Given the shape of the flue, using a circular line that will fit looks like it leaves the flue way too undersized and I haven't noticed an oval/rectangular liner to round Class A adapter. Any advice on that transition/sizing issue?

Thanks!

 

[bholler]

well you will need a 14" diameter pipe to match the flue size. While yes you can get that and have a custom adapter made it will be much cheaper to just extend it with brick

 

[rustlerski]

Thanks. Given the patio surrounding the fireplace and the house foundation, I'm not sure there's much of a way to check the foundation of the fireplace itself to see if it can support the extra weight.

 

[bholler]

Thanks. Given the patio surrounding the fireplace and the house foundation, I'm not sure there's much of a way to check the foundation of the fireplace itself to see if it can support the extra weight.

If it was built properly to begin with there will be no problem but that is hard to determine. Have you had any masons look at it?

 

[rustlerski]

Not yet. Still in planning stages and trying to get a sense of best options.