Can You Use Single Wall Stove Pipe Outside?
Stoves, fireplaces, chimneys and furnaces need to be vented in order to properly, and safely, guide smoke and gases outside of the home.
Both single and double-walled stovepipe is only permitted indoors. When you transition to the outside through an insulated thimble, you must use “Class-A Chimney” which is insulated.
The reasons for this are function, code, and safety.
No, you cannot use single wall stove pipe outside. It’ll lose its integrity over time, and will not keep the gases hot enough to prevent the toxic creosote buildup. Without the insulating layer, it will cause cold hearth syndrome, and force the smoke back into your home. You need a Class-A chimney to vent outside.
Class-A Chimney Pipe
This type of pipe, often referred to as double-wall chimney pipe, triple-wall chimney pipe, all-fuel pipe, or insulated chimney pipe, is used to vent wood-burning chimneys.
Class-A chimney pipe is made using a stainless or galvanized outer wall. It is recommended to install your chimney in the interior of your home. Having your system exposed to the outdoors can create toxic build-up.
Referred to as “cold hearth syndrome”, this hinders drafting and produces more creosote.
Cold Hearth Syndrome
This occurs when fireplaces and chimneys that share an outside wall, or are outside, are inadequately isolated from the cold. When the average temperature falls below that of the house, it causes a backdraft that pushes the smoke into the house.
Creosote is a dark brown oil distilled from coal tar and used as a wood preservative. Brief exposure to large amounts of creosote may result in many adverse health effects:
- rash or severe irritation of the skin
- chemical burns on the eyes
- convulsions and mental confusion
- kidney or liver problems
- unconsciousness, and even death
On top of health effects, there is a strong possibility of fire. This will damage not only your chimney system, but your entire home. This is why it is important when planning out your chimney to follow proper safety protocols.
Sticking with the Manufacturer
The high-temperature exhaust that is released from wood, coal, and oil-burning appliances needs to be vented. Fireplaces, stoves, boilers, and furnaces all need an exhaust piping system in place.
The venting system that is used requires a Class-A pipe in order to safely exhaust this to the outside of your home. Class-A chimney pipe is UL-listed, which permits its use with a range of different vent pipe manufactured by many fabricators.
You should never mix and match different brands of Class-A chimney pipe within one system unless the manufacturer explicitly states it is okay. Every brand of pipe is engineered for use within that closed system, from beginning to end. They are not meant for alternative brands to be used.
If you are extending, redesigning, or replacing parts of an existing system it is imperative that you stay within the make and model of your existing pipe system. If your existing system is no longer built, then you will unfortunately need to rebuild your system from scratch.
Building codes outlaw the use of any adapters that are not approved by the manufacturer, for safety reasons. These adapters are very rare and usually only offered to link a similar discontinued piping system.
Types of Class-A Chimney Pipe
There are two types of Class-A chimney pipe, they are:
- Solid-packed chimney — These pipes have smaller inner diameters and insulation. Within the 5” – 8” range, they are either double-wall or triple-wall. The insulation is either ceramic or fiberglass and made to stay cooler on the outside.
- Air-cooled chimney — These pipes have much larger inner diameters then solid-packed chimney. They also have no insulation. These pipes rely on the air circulating inside of them to keep the outer wall cool, which is easier with the 8” – 24” inner diameter.
Stovepipe, also referred to as a chimney connecter, is used for venting wood-burning stoves. This type of pipe is only used for the room in which the stove is installed and stays inside the home.
When the venting reaches the wall or ceiling, you then convert the piping to the Class-A chimney pipe. Depending on the different clearances will determine which Class-A chimney pipe will allow for the proper venting of your stove.
Problems with Single Wall Stovepipe
Most wood stoves need a large draft to operate correctly and loss of heat through a single wall pipe causes too much loss of draft.
Stovepipe is not permitted to go through a ceiling or wall, regardless of how much clearance there is. These pipes were not engineered for that use, that is what Class-A chimney pipes are for.
Installing Stovepipe into a Chimney
There are a handful of ways to go from a wood stove pipe to a chimney pipe, to get the proper venting to follow safety protocols.
Through the Ceiling
If your venting system runs vertically through your ceiling, you will need a ceiling support box to use as a transition point. You can also use a round ceiling support piece to go from the stove pipe to the Class-A chimney pipe.
The stove pipe will connect to the bottom and the Class-A chimney pipe will be on the other side, running up into the attic insulation or the ceiling support box. The next step will be on through to the roof flashing.
Through the Wall
If your venting system runs horizontally through the wall, then you need to use a thimble. A thimble allows a Class-A chimney pipe to pass through the wall and run into the room where the appliance is located, connecting to the stove pipe.
Again, it depends on what kind of stovepipe you are using to know how far into the room the chimney pipe must come. This would be 6” for connecting to a double-wall stovepipe and 18” for connecting to a single-wall stove pipe.
Chimney Termination Caps
On top of residential homes you will see termination caps, these are fitted on top of the pipe where it comes through the roof. Class-A chimney pipes have a specialized set of caps and follow specific rules regarding the size.
This is what’s known as the ’10-3-2’ rule. According to the Natural Fire Protection Association (NFPA): “A chimney for residential-type or low-heat gas utilization equipment appliances shall extend at least 3 ft (0.9 m) above the highest point where it passes through a roof of a building. At least 2 ft (0.6 m) higher than any portion of a building within a horizontal distance of 10 ft (3 m)”
How Long Does Single Wall Stove Pipe Last?
A high-quality stainless-steel flue liner will last 15 – 20 years. A lower grade flue liner will last 2 – 3 years. This is why it is important to always purchase high-quality stove pipe.
How Big of a Stove Pipe Do I Need?
The flue size should be 25% larger than the size of the stove pipe. A stove with a 6” diameter pipe would require an 8” flue. An 8” stove pipe requires a 10” flue.
At What Temperature Does Creosote Ignite?
Creosote will ignite at 1,200 – 2,000 degrees Fahrenheit. It can be ignited with just one spark and cause massive risk to the health of anyone nearby.86% of wood heat-related fires originate from the chimney or stovepipe, when creosote ignites.
Sean Jarvis is an interior decorator, writer, and expert handyman. Well versed in everything home improvement, he is a savant at manipulating words and spaces and upgrading everything around him. Sean specializes in writing concise guides about appliance repair and installation, home and lifestyle, and other residential projects.
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