Looking for new chimney help

[Glory]

I am building a new detached garage. I plan on installing a class A vent for future heating.

I have been trying to understand the required chimney height vs. spacing from the roof slope/peak or the 10’, 2’, 3’ rule. I may be over thinking this.

I have a 4:12 roof and would like to locate the chimney approx 4’ away from the peak.

So can any of you guys tell me how tall the chimney needs to extend above the roof?

 

[ddawg16]

Here is a logical reference....matches my house

https://inspectapedia.com/chimneys/Chimney_Height_Codes_Specifications.php

Basically....measure down 2' from the top of the chimney....then over 10' to the roof. If it's 10' or more, you are good.

 

[Kaizen]

Four feet away from the peak then the chimney has to be two feet above the peak. Not sure if that amount includes the cap though. Your total height of pipe above roof should be 40inches as the four feet away should be 16 inches in elevation plus the two feet.


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[mrobins297aaa]

if your 48" from the peak, per your sketch you need to be 40" above the roof.
4/12 roof pitches 16" in 4' + 24" above the peak = 40" above the roof at the roof penetration

 

[mrobins297aaa]

oops just like Kaizen said

 

[Glory]

Appreciate the assistance fellas. 40” measured from the uphill side, sounds like a 48” stick will work perfect.

 

[James-W]

I don't know about you guys but if it were me I would first decide what type of heater I wanted to use. Depending on what heater you get you may be able to vent it out of the side of the building rather than the roof.

 

[Glory]

I don't know about you guys but if it were me I would first decide what type of heater I wanted to use. Depending on what heater you get you may be able to vent it out of the side of the building rather than the roof.

Interesting James-W. I am a novice at residential construction, but I was under the impression that any side vent, regardless of configuration is less efficient than a straight vertical vent. So if it’s new construction and vertical vent is feasible, what would make you consider a horizontal vent?

Also, I hear you on deciding on the heater first. My situation is I am very limited on funds and using what I have to complete the structure. Since I live in the desert, heating is one of my last concerns. Only reason I am choosing to install the chimney now is I will have the penetration under my roof warranty from the roofing company.

I tried to mitigate the risk and leave myself options by selecting a double wall class A vent. My understanding is this type of vent is rated for many different types of furnaces/heating equipment.

 

[James-W]

Interesting James-W. I am a novice at residential construction, but I was under the impression that any side vent, regardless of configuration is less efficient than a straight vertical vent. So if it’s new construction and vertical vent is feasible, what would make you consider a horizontal vent?

Also, I hear you on deciding on the heater first. My situation is I am very limited on funds and using what I have to complete the structure. Since I live in the desert, heating is one of my last concerns. Only reason I am choosing to install the chimney now is I will have the penetration under my roof warranty from the roofing company.

I tried to mitigate the risk and leave myself options by selecting a double wall class A vent. My understanding is this type of vent is rated for many different types of furnaces/heating equipment.

I have a natural gas heater and it has a blower for venting the exhaust gases. I have no idea what types of fuel you have available for heating, but if you have natural gas I would definitely go with it. Also, venting thru the wall, in my opinion anyway, is better than venting thru the roof simply because you aren't putting a hole in the roof. Obviously, if the roof vent is done correctly there won't be a problem with water leaking in. But not having a roof vent, if possible, would seem to me to be the best way of doing it.

 

[mrobins297aaa]

I might be wrong here but I think some of those power vented heaters can use type "B" venting when you vent thru the roof, which is a lot cheaper than the expensive stainless vents if you vent thru the wall.

Also I don't think that 2' above 10' rule applies to power vented equipment,
It's been a while since I checked so that might also be something to check into.

 

[Glory]

Unfortunately natural gas isn’t available where I live.

 

[brewchief]

Type A pipe is needed for wood burners and oil burners, it can be used with gas burning heaters but is a much more expensive option.

Check with your insurance company before planning a wood burning stove as some will not cover them in a detached garage.

Type A pipe needs to be supported, typically you mount a ceiling support box at your finished ceiling (bottom of trusses) and build up from there, depending on the size of building you could need 8-10 feet of pipe to reach from the support box to the needed height above the roof, this can be expensive.

If LP gas is an option a simple unit heater might be a good option and could be vented with much less expensive type B vent if vertical or with stainless if venting horizontally.

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[Glory]

Type A pipe is needed for wood burners and oil burners, it can be used with gas burning heaters but is a much more expensive option.

Check with your insurance company before planning a wood burning stove as some will not cover them in a detached garage.

Type A pipe needs to be supported, typically you mount a ceiling support box at your finished ceiling (bottom of trusses) and build up from there, depending on the size of building you could need 8-10 feet of pipe to reach from the support box to the needed height above the roof, this can be expensive.

If LP gas is an option a simple unit heater might be a good option and could be vented with much less expensive type B vent if vertical or with stainless if venting horizontally.

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Great information. As I researched I decided to purchase a 6T-FCK from amazon and a section of 48” and 36”.
https://www.northlineexpress.com/6-selkirk-flat-ceiling-support-kit-6t-fck-5347.html

So if I am understanding correctly, I can stop at the ceiling support box and build the lower section at a later date?

 

[PCustoms]

So if I am understanding correctly, I can stop at the ceiling support box and build the lower section at a later date?

Yes. The pipe inside the house will need to be the same brand to interface with the ceiling support box. It will either be single wall (larger clearances required) or double wall.

I have a few pieces of double wall left over from my install if you are interested.

 

[Bretny]

If this is for a wood stove make sure you add a slip joint in the single wall. Will make it easier for chimney cleaning and stove install/maintenance easier. Some tripple wall to single wall adapters have this built in.