Rebuild Brick Above Roofline or Wood Chase

[GrnMtn]

I have to rebuild my chimney above the roofline, it is too short (2'), flashing has eroded, and needs to be repointed. I had a mason look at the chimney and he recommended re-building the chimney 8' above the roofline (low pitch metal roof). I have a 2 flue stack both with clay liners (1 has a stainless stell liner as well). To rebuild and cap 1 chimney its $3,700 and to rebuild both would be $6,700. One fireplace is on the 2nd floor and 1 fireplace is on the first floor.

Alternatively, would it make more sense to build above the roofline with a wood chase chimney? Going down that route I could put a fireplace insert in one of my fireplaces and have the benefit of a better heat source. Is this a feasible approach? Would the cost (excluding the cost of the fireplace insert) be lower? Or is this just not a good idea. A mason I met last year recommended this, unfortunately he moved out of the area.

Any thoughts on the best approach are appreciated!

 

[begreen]

Sounds feasible if the chimney transitioned to metal class A pipe. Was that what was suggested?

 

[GrnMtn]

Sounds feasible if the chimney transitioned to metal class A pipe. Was that what was suggested?

He suggested putting in stainless steel pipe up the masonry chimney stack (inside the current liner). Then continue pipe above roofline and enclose.

 

[begreen]

That is correct except that once the flue transitions from masonry to pipe it needs to be insulated class A stainless pipe. Does the chimney exit on the low side of the roof or near the peak?

 

[GrnMtn]

The chimney exits nearer to the peak, it's a relatively flat roof (low pitch metal). I assume going up about 8' is only possible with a chase. I assume I can't use metal braces due to the lack of roof pitch.

I'm guessing this might be lower cost than going all brick. If it's not, then I might as well go with the brick.

 

[begreen]

I'm trying to understand why the 8' increase. It only needs to be 3 ft above the roof exit and 2' above the nearest roof within 10 ft. However, if you want to add an insert it should have at least 15 ft of chimney. Perhaps that is the reason for the 8'?

 

[GrnMtn]

The current stack is 7' with 2' above the roofline for the upstairs chimney. The down stairs is considerably longer.

 

[begreen]

If the goal is to heat with an insert you will most likely want the insert in the downstairs fireplace. That should add another story of chimney which would be sufficient. It's hard to say without seeing the actual chimney but based on the description I would only raise/repair the chimney to 3 ft above the roof if that clears the peak by 2 ft. That should be much less expensive. Then drop an insulated stainless liner down to the downstairs fireplace for the insert installation.

Maybe get a csia certified sweep out to look at the job and see if they are qualified to do the whole job for you. They may even install the insert.
www.csia.org

 

[Hogwildz]

If cost is concern, you can also run the class A up through the roof through a flashing and forgo the masonry or chase. The roof of course will have to be patched in around the flashing.
You will have to raise the height of the stack up for the upstairs. BG nailed it at using the lower level for use & heating.