Pole Barn Chimney Questions

[AH64ID]

I am in the planning phase of installing my newly acquired wood stove in my pole barn.

I have searched and read a bunch of threads but want to ensure I am reading everything correctly.

Here is the overall layout.

FABCO Briarwood II stove with 6" flue mounted in a corner, with plenty of clearance.
~16.5' to the roof
~4.5' needed above roof for 10/3/2 rule
Roof is a corrugated metal roof with OSB underlayment that will be trimmed for at least 2" clearance.
Trusses are 12' apart and purlins are 24" OC.
Chimney pipe will exit (centered) 12" from purlins and 24" from closest truss.

I am currently looking at using the DuraVent brand for my installation.

What I am planning on is this, working from the stove up.

DuraBlack Stovetop Adapter
3 sections of 6"x48" DuraBlack Single-Wall Black Pipe
1 section of 6" x 48" DVL Double-Wall Black Pipe (I understand DVL and DuraBlack are connectable)
DVL/DuraBlack Chimney Adapter
1 section of 6"x60" DuraTech Chimney Pipe supported with a DuraVent Adjustable Roof Support
High Temp Silicone Roof Flashing
Chimney Cap

I will likely do some sort of brace as well.

As I understand it that will allow me 2" clearance to combustibles thru the roof, and the support bracket will support the weight of my entire chimney/pipe.

The Duratech will extend approx 1' below my roof allowing for plenty of clearnce if I ran single wall up to the chimney pipe, but I want the last 4' to be DVL to maintain the flue temp.

How does that look?

This is a permitted installation and will have to pass inspection, and I only want to do it once.

 

[begreen]

I'm not a fan of the flexible boot. My preference is for a stiffer metal roof flashing and a framed in regular ceiling support box. Then no roof brace should be necessary. Did you check out Highbeam's pole barn install?
https://www.hearth.com/talk/threads/installed-englander-30nc.115825

 

[AH64ID]

I did see his installation, but he planned on a flat metal ceiling which is something I won't have.

As far as I understand the flashing should have zero support for the chimney, so it doesn't matter if it's flexible or solid as it's job is to keep water out rather than support.

I will be under the 5' of exposed chimney that "requires" a support but we are in a high wind area and I will have around 4' exposed.

 

[bholler]

I did see his installation, but he planned on a flat metal ceiling which is something I won't have.

As far as I understand the flashing should have zero support for the chimney, so it doesn't matter if it's flexible or solid as it's job is to keep water out rather than support.

I will be under the 5' of exposed chimney that "requires" a support but we are in a high wind area and I will have around 4' exposed.

I prefer metal flashing as well

 

[begreen]

I did see his installation, but he planned on a flat metal ceiling which is something I won't have.

As far as I understand the flashing should have zero support for the chimney, so it doesn't matter if it's flexible or solid as it's job is to keep water out rather than support.

I will be under the 5' of exposed chimney that "requires" a support but we are in a high wind area and I will have around 4' exposed.

A metal flashing does not support but it keeps the chimney from wobbling. It also is easier to keep the 2" clearances around the pipe in the hole thru the roof and it uses way less screws to hold it in place. With the silicone boot there is a ring of screws that are very close to the hole one has to make for the pipe in order to ensure 2" clearance. That is not very strong especially with with a chipboard roof underlayment. My 2 cents worth, but folks have used the boot and some say they like it.

 

[AH64ID]

A metal flashing does not support but it keeps the chimney from wobbling.

That sounds like it supports it, but I see what you're saying.

It also is easier to keep the 2" clearances around the pipe in the hole thru the roof and it uses way less screws to hold it in place. With the silicone boot there is a ring of screws that are very close to the hole one has to make for the pipe in order to ensure 2" clearance. That is not very strong with a chipboard roof.

Good point.

The adjustable roof support, made by DuraVent, should keep the chimney centered in the hole as well as provide vertical and lateral support at the base of the roof (the flexible collar goes on after). I was then considering a roof brace higher up, thou not sure it's needed, due to the higher wind. That would give me two later supports from the roof up.

Another reason for the flexible collar is ease of installation. Adding a metal flashing to an existing metal roof takes a new section of roofing to be done properly. There are lots of flexible collars in this area and they work well. We, on average, get less than 12" of rain a year which also reduces the desire for a metal flashing install.

If I had done the stove installation at the same time as the roof it would be metal... but I didn't and it's going to be flexible.

 

[bholler]

That sounds like it supports it, but I see what you're saying.



Good point.

The adjustable roof support, made by DuraVent, should keep the chimney centered in the hole as well as provide vertical and lateral support at the base of the roof (the flexible collar goes on after). I was then considering a roof brace higher up, thou not sure it's needed, due to the higher wind. That would give me two later supports from the roof up.

Another reason for the flexible collar is ease of installation. Adding a metal flashing to an existing metal roof takes a new section of roofing to be done properly. There are lots of flexible collars in this area and they work well. We, on average, get less than 12" of rain a year which also reduces the desire for a metal flashing install.

If I had done the stove installation at the same time as the roof it would be metal... but I didn't and it's going to be flexible.

You dont have to add a new sectio of roofing at all. You just make a slit the width of the flashing just below the hole you cut for the chimney and slide the top of the flashing up under the roof. If done right there are just 2 small spots that need a tiny bit of caulk. There is much less potential for failure. There is nothing wrong with the flexible flashing it just is not as durable or long lasting as metal.

 

[AH64ID]

You dont have to add a new sectio of roofing at all. You just make a slit the width of the flashing just below the hole you cut for the chimney and slide the top of the flashing up under the roof. If done right there are just 2 small spots that need a tiny bit of caulk. There is much less potential for failure. There is nothing wrong with the flexible flashing it just is not as durable or long lasting as metal.

I've heard that inserting the metal flashing that way is more prone to leaks and was steered away from it. I have no personal experience with it thou.

Thank you.

 

[bholler]

I've heard that inserting the metal flashing that way is more prone to leaks and was steered away from it. I have no personal experience with it thou.

Thank you.

I have done atleast 50 that way with no issues at all.

 

[begreen]

Take a look at the Excel metal roof flashing. It's designed for this type of installation. It's installed like bholler described and the bottom edge can be notched to conform to a rib. In the example below, the flashing was close enough to the ridge that they stuck the upper edge under the ridge vent cap. This pic is before the storm collar was put on.

another installation