Chimney/flue question

[jmargush]

I am at the point where I need to build my chimney.

The clay flue liner is attractive form a price and durability point., but I am not sure if my planned house construction will allow it to work.

Could I run the clay flue up from the vent then through the roof and only have a minimal (10-12")amount of the clay flue exposed, with out having a "chimney around it?

My plan was to use concrete board for the house and stucco it. The roof I am investigating some sort of terra cotta tile or composite version but not sure what the best sheathing to use will be.

If I can go through the roof with the clay flue liner:

Do I need and air gap?

What do you use to seal or flash the flue to the roof?

[UtahBeehiver]

I think Tscar answered this in another post (he knows his brick work stuff). The flue temps get really hot so the flue liner will as well. This is why there are 4" brick around the flue liner and air gaps around the brick chimney.

[jmargush]

I know there was an answer to another post but that post didn't explain the house construction.

when clay liners are used on houses the clay liner usually extends up beyond the chimney by several inches so that a cap and be put on it.

[UtahBeehiver]

I guess I don't understand, I thought the question was "can I run the clay flue through the roof without a chimney (masonary wrap) around it and no air gap".

[jmargush]

Is a masonry chimney needed inside the house area?

If not and the clay flue only extended up out above the roof approx. 10-12" would you need a masonry chimney around that much?


Could a chimney be made by framing a box(and leaving an air gap) with metal studs and sheathing with concrete board?

[UtahBeehiver]

I am going to defer to Tscar or Gulf both built fully enclosed chimneys. I used double wall SS venting and without an enclosure.

[david s]

The problem is a very hot flue liner too close to timber surrounding it could be a fire hazard. Also sealing against the hot flue liner may present some problems. If the flue liner is subject to cold air surrounding the outside (uninsulated) it is more prone to cracking, especially lower down where it is subjected to greater temperatures on the inside surface.

[DavidApp]

Stainless Steel double wall chimney is the way to go.
It can be 20' or more without subjecting your vent to a large load and in most cases it is OK by the fire inspectors as it is used on wood stoves.

David

[gastagg]

Have you checked Craigslist for SS double wall chimney? I found 2-30", 1-18", and a rain cap all for $40 locally. It's 6". I think you need 8" or 10".

[Gulf]

In your case, I would have to agree with the SS double wall pipe recommendations. You don't have any where near the room on the front of your inner arch transition to get enough clearance for boxing in a clay liner with concrete board. According to some codes that is 9" from single wall stove pipe to a heat shield, with another 1" of airspace behind that to any combustibles.(You asked about using wood framing in this question) And those clearances are based on an open room. Not in an enclosed attic where a double walled transition and piping is required. I would imagine that those clearances would be the same for a clay liner. But. I'm thinking about this from the possibility that your liner will crack. If your clay liner cracks or leaks, I would hate to think that hardiebacker was all that is left to contain a "fire from hell". Also, I don't think that your stand/hearth has the support for the weight of wrapping the liner with masonry.

[SimonMALTA]

Hi can anyone help,

I intend to do a stainless steel flue, does it need to be insulated or not?

Regards
Simon