DIY Class A chimney install

[RustyShackleford]

I'm helping a friend with a Blaze King (probably Princess) install. For various reasons, it seems as though their current masonry chimney is inadequate; the opening is way too low and the liner doesn't look in great shape.

So I'm thinking of recommending a new Class A metal chimney; it's only affordable if we can DIY it, so I want to explore that. I have decades of experience with wood burning, I'm an engineer, and I have a lot of successful DIY experience. So despite the obvious risks, I think it's reasonable.

It looks like the materials can be had for no more than $2000. Attached is a shopping cart totaling $1700 (the locking bands are chopped off the bottom of the file), and I'm sure there's various braces and roofing supplies needed, and probably something I'm overlooking. I'm confused about whether this piece is needed in an un-occupied and un-insulated attic (there is, of course, insulation in the ceiling joists on the floor of the attic): https://www.efireplacestore.com/cpf-70672.html ... if you frame things so as to keep the batts 2" from the pipe.

The install instructions look pretty comprehensive ( the URL doesn't seem to work but google "duratech instructions"); it seems like the key points are:

1. The chimney reaches high enough - 2ft above the highest thing within 10ft horizontally.
2. Seal the roof penetration flashing properly.
3. Brace the ceiling support box adequately.
4. Keep all combustibles at least 2" away.

 

[DAKSY]

Class A also has to extend a MINIMUM of 3 feet out of the roof before the 2’ higher than anything within 10’ rule applies…

 

[Turbo89]

That piece is only if you’re going to fill insulation above the studs/rafters and Is not required if you don’t have / aren’t planning to add it. Lowe’s used to have a kit that included that, the roof flashing and the ceiling box kit for almost the same money… with checking out for DIY.

It sounds like you have a good grasp on the rules, this image helped when I did /checked mine. Also make sure meet the minimum flue length recommended by the stove manufacturer/model.

 

[RustyShackleford]

Thanks. Yeah the 2ft above anything within 10ft will easily make the 3ft thing moot.

 

[RustyShackleford]

It sounds like you guys think I'm not biting off more than I can chew with a DIY install, and that $2000 is a reasonable estimate of materials cost.

I think I'm going to recommend that; I really don't think they're going to get satisfactory stove performance otherwise. Attached is a document of inspection of their existing masonry chimney with liner. It doesn't look great. Furthermore, the hole in the side (where the stovepipe enters) is so low that there's not going to be anywhere near the recommended 2ft of vertical coming out of the stove before the the elbow.

 

[chimneychick]

All I can say is to FOLLOW THE INSTRUCTIONS TO THE LETTER
Use the proper flashing for the roofing materials
Enclose any chimney that is exposed in a living area
Ensure all connections are tight and sealled
But ion looking at the photos,
are you sure that just installing a proper stainless steel lining system with base tee and SS breech will not do th trick properly without the expensde of nuying an entire new chimney system?? Have you gotten a second opinion on the chimneys heath?

 

[Turbo89]

All I can say is to FOLLOW THE INSTRUCTIONS TO THE LETTER
Use the proper flashing for the roofing materials
Enclose any chimney that is exposed in a living area
Ensure all connections are tight and sealled
But ion looking at the photos,
are you sure that just installing a proper stainless steel lining system with base tee and SS breech will not do th trick properly without the expensde of nuying an entire new chimney system?? Have you gotten a second opinion on the chimneys heath?

I overlooked this (and don’t see any pictures); but agree if it just needs to be re-lined that’s a heck of a lot less work. You can pretty easily move the thimble up too, with a new liner (look up instructions online, they’re surprisingly easy to put in).

You can cap the lower thimble or patch it with the bricks you remove.