New exterior wall chimney with an offset?

[mthoodfire]

Due to some complexities with going through the ceiling and roof, we likely have to do an exterior wall chimney for a Drolet Deco-II wood stove. I plan on using double-wall pipe all the way from the stove up. I realize the exterior chimney adds 2 90-degree bends, one to exit the wall and one to go up the chimney. What we are dealing with is trying to find a way to get around 12" eves on the house, would it be permissible to use 15-degree offsets to extend beyond the eve and then return to vertical? I know offsets are often used in interior chimney pipe, but I can't find anything stating one way or the other for exterior.

Some of the challenges are trying to incorporate this into a standing seam roof and not ending up with leaks, we are in a very wet climate (temperate rain forest) and we just got done replacing insulation and drywall from a previous roof leak and getting the new roof installed based on weather.

At this point it would be DuraTech 6" dual-wall chimney pipe and DuraVent's DVL dual-wall stove pipe, unless people feel strongly that this is more doable with other chimney pipe solutions.

Am I asking for nothing but trouble on getting draft? Sadly, I am not sure anything else would work. If we had to go directly vertical it just adds more complexity to get the seams all sealed up, as I don't thin the flashing would fit within a single roof panel. The Rock-Vent flashing looks like it would be slightly easier to work with, and maybe we could get perfectly lucky and the flashing would fit within a single 16" roof panel between seams...but I haven't found any good dimensional drawings of any of the flashing/boots. If our placement could align with the peak/ridge it would be possibly be easier, but that isn't the case due to where the interior walls are.

 

[stoveliker]

How tall would the system be from stove top to chimney cap?

 

[webby3650]

Many chimney manufacturers don’t allow elbows outside of the structure, I’m almost certain dura-vent is one of them. If I did, it would be 30 degree elbows, so it has less of an offset.
We have done hundreds of metal roof flashings, I feel most confident with a flashing in standing seam. Why do you have no confidence in a pro making this penetration?

 

[mthoodfire]

How tall would the system be from stove top to chimney cap?

Full height gain from the top of the stove to the cap is likely close to 17-18', with ~13.5' of that being the external chimney pipe.

Many chimney manufacturers don’t allow elbows outside of the structure, I’m almost certain dura-vent is one of them. If I did, it would be 30 degree elbows, so it has less of an offset.
We have done hundreds of metal roof flashings, I feel most confident with a flashing in standing seam. Why do you have no confidence in a pro making this penetration?

I haven't had much luck in finding any chimney installers so far. Most of the shops I've talked to are accustomed to just running a line up an old masonry chimney, and others won't talk to me since I didn't buy a stove from them as they don't carry a stove I want. Do you use metal flashing or a rubber boot like the one Selkirk offers?

Truly appreciate all of the wisdom on this forum, thanks for your time in replying.

 

[Urban Homesteader]

Due to some complexities with going through the ceiling and roof, we likely have to do an exterior wall chimney for a Drolet Deco-II wood stove. I plan on using double-wall pipe all the way from the stove up. I realize the exterior chimney adds 2 90-degree bends, one to exit the wall and one to go up the chimney. What we are dealing with is trying to find a way to get around 12" eves on the house, would it be permissible to use 15-degree offsets to extend beyond the eve and then return to vertical? I know offsets are often used in interior chimney pipe, but I can't find anything stating one way or the other for exterior.































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































Some of the challenges are trying to incorporate this into a standing seam roof and not ending up with leaks, we are in a very wet climate (temperate rain forest) and we just got done replacing insulation and drywall from a previous roof leak and getting the new roof installed based on weather.































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































At this point it would be DuraTech 6" dual-wall chimney pipe and DuraVent's DVL dual-wall stove pipe, unless people feel strongly that this is more doable with other chimney pipe solutions.































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































Am I asking for nothing but trouble on getting draft? Sadly, I am not sure anything else would work. If we had to go directly vertical it just adds more complexity to get the seams all sealed up, as I don't thin the flashing would fit within a single roof panel. The Rock-Vent flashing looks like it would be slightly easier to work with, and maybe we could get perfectly lucky and the flashing would fit within a single 16" roof panel between seams...but I haven't found any good dimensional drawings of any of the flashing/boots. If our placement could align with the peak/ridge it would be possibly be easier, but that isn't the case due to where thesimilar insetup isterior walls are.















































































My setup is similar to what you are looking to install. 90 through the wall to a T and up to a 30 degree bend to get past the the eve and another 30 degree bend to straighten out.



Had some problems with draft issues and smoke spilling into the room. Last year I installed an OAK and haven't had any of those problems since. My best advice is if you plan on installing your chimney that way, do yourself a favor and install an OAK.

 

[all night moe]

With that height, I have found that offsets disrupt the draft. Like mentioned, the lesser 30 degree offsets are a bit better.

If you cannot find someone to help with penetrating your eve, another option would be to construct an insulated chase, and still use a class A chimney system.

 

[Urbanhomesteader]

My setup is similar to what you are looking to install. 90 through the wall to a T and up to a 30 degree bend to get past the the eve and another 30 degree bend to straighten out.



Had some problems with draft issues and smoke spilling into the room. Last year I installed an OAK and haven't had any of those problems since. My best advice is if you plan on installing your chimney that way, do yourself a favor and install an OAK.

 

[webby3650]

Full height gain from the top of the stove to the cap is likely close to 17-18', with ~13.5' of that being the external chimney pipe.

I haven't had much luck in finding any chimney installers so far. Most of the shops I've talked to are accustomed to just running a line up an old masonry chimney, and others won't talk to me since I didn't buy a stove from them as they don't carry a stove I want. Do you use metal flashing or a rubber boot like the one Selkirk offers?

Truly appreciate all of the wisdom on this forum, thanks for your time in replying.

We use metal roof flashings made by Excel. I would never use a rubber boot, they offer no support and often leak.

 

[stoveliker]

Full height gain from the top of the stove to the cap is likely close to 17-18', with ~13.5' of that being the external chimney pipe.

With two elbows and a horizontal run, both of which reduce draft, 17-18' might be borderline insufficient.

 

[bholler]

We use metal roof flashings made by Excel. I would never use a rubber boot, they offer no support and often leak.

And deteriorate pretty quickly as well

 

[begreen]

And deteriorate pretty quickly as well

And they require a lot of screw holes to fasten down the skirt.

 

[all night moe]

I understand why the rubber boots are used. It is impossible to open up the seams on a standing seam roof and reuse the seams, hence the rubber boots. I still would not use the rubber boots do to the limited longevity and all the penetrations of fasteners.
I, personally, would build a chase and flash that into the roof. That said, I have a few decades of experience in home renovations. Roofing being one of my dominate trades. Started there as a young buck.

 

[bholler]

I understand why the rubber boots are used. It is impossible to open up the seams on a standing seam roof and reuse the seams, hence the rubber boots. I still would not use the rubber boots do to the limited longevity and all the penetrations of fasteners.
I, personally, would build a chase and flash that into the roof. That said, I have a few decades of experience in home renovations. Roofing being one of my dominate trades. Started there as a young buck.

There is no need to open up the seams to install metal flashing

 

[begreen]

There is no need to open up the seams to install metal flashing

Agreed, I have not seen that done.

Example from Rockford's website.

 

[bholler]

Agreed, I have not seen that done.

If I were installing flashing with a view roof install I would overlap roof panels etc but it absolutely is not nessecary to have a watertight install

 

[all night moe]

There is no need to open up the seams to install metal flashing

Agreed, I have not seen that done.
View attachment 304983
Example from Rockford's website.

Wow, i have never seen an install like this on an existing roof.
I learned something new today. Rockford, huh? Time to investigate how this flashing works.
Thank you both for the tid bit of info!

 

[begreen]

Link to Rockford. This looks like the Ventis flashing.

Metal Roof Flashing for Chimney Pipe Install | Rock-Vent Roof Flashing - Rockford Chimney

Variety of roof pitches available for the Metal Roof Flashing for your Rock-Vent Class A chimney pipe install. Solves challenges of metal roof flashing.

www.rockfordchimneysupply.com

Excel makes a metal roof flashing also. It looks like this.

 

[all night moe]

After just visiting their website, I'm thoroughly impressed.
I'd still have to build a chase from the eve down to stove, just to satisfy my HO insurance company.

 

[bholler]

Wow, i have never seen an install like this on an existing roof.
I learned something new today. Rockford, huh? Time to investigate how this flashing works.
Thank you both for the tid bit of info!

You don't even need the specialized metal roof flashing I usually just use regular flashing. But the metal roof flashing makes it easier

 

[mthoodfire]

Thanks again for all of the really helpful info. After measuring everything again I think our eve overhang is just wide enough to fit the 6" dual wall, it has exactly 12" clearance from the wall to the fascia board. Worst case I could cut the fascia board and run metal to bridge the "gap" to give more clearance.

We are also considering a new location that might allow us to go straight through the ceiling and up through the roof. The Rockford and Excel flashing both look better than most of the other options, I had wondered about the rubber boot durability. The upside is my roof gets no sun so there is no UV, the downside is my roof gets no sun and stays wet for long periods of time.

 

[mthoodfire]

Link to Rockford. This looks like the Ventis flashing.

Metal Roof Flashing for Chimney Pipe Install | Rock-Vent Roof Flashing - Rockford Chimney

Variety of roof pitches available for the Metal Roof Flashing for your Rock-Vent Class A chimney pipe install. Solves challenges of metal roof flashing.

www.rockfordchimneysupply.com

Excel makes a metal roof flashing also. It looks like this.
View attachment 304984View attachment 304985

This flashing looks like a solid choice, as does the Rockford. I hadn't looked at Excel previously, they don't seem to get as much mention as some of the other brands (e.g Duravent & Selkirk) but their round support/radiation barrier for the insulation protection looks like a far more graceful install.

 

[mthoodfire]

After just visiting their website, I'm thoroughly impressed.
I'd still have to build a chase from the eve down to stove, just to satisfy my HO insurance company.

I am curious about this, your HO insurance company has specific rules that require all chimneys to be enclosed? Are you in an area with higher risk of wild fire or wind issues? I am just curious as to why they would have specific requirements about it.

 

[mthoodfire]

My setup is similar to what you are looking to install. 90 through the wall to a T and up to a 30 degree bend to get past the the eve and another 30 degree bend to straighten out.



Had some problems with draft issues and smoke spilling into the room. Last year I installed an OAK and haven't had any of those problems since. My best advice is if you plan on installing your chimney that way, do yourself a favor and install an OAK.

Would you mind telling me more about this "OAK", as you can imagine searching for it turns up a lot about hardwood. I think I have found a way around it, and it appears that Excel may be the only chimney pipe that actually allows exterior offsets. I am still intrigued as to what this "OAK" item is though.

 

[bholler]

This flashing looks like a solid choice, as does the Rockford. I hadn't looked at Excel previously, they don't seem to get as much mention as some of the other brands (e.g Duravent & Selkirk) but their round support/radiation barrier for the insulation protection looks like a far more graceful install.

Rockford is selling ventis chimney. That and excel are the two real premium chimneys. Jeremiahs is a nother premium one that is just starting to make a presence in the US. The other ones are more common because they have been available for retail sale for a long time

 

[colin.p]

Would you mind telling me more about this "OAK", as you can imagine searching for it turns up a lot about hardwood. I think I have found a way around it, and it appears that Excel may be the only chimney pipe that actually allows exterior offsets. I am still intrigued as to what this "OAK" item is though.

OAK=Outdoor Air Kit

Oh, and I have 2X30 degree offsets outside and no appreciable issues with draft (120 year old very drafty 2 story farmhouse). However a real PITA to clean.