Quick Answer
Each component has its own clearance. For listed products, the listing and installation instructions control.
- Class A insulated chimney pipe: commonly 2 inches. Shasta Vent All-Fuel HT requires a 2-inch air gap.
- Single-wall connector (stove pipe): 18 inches for an unlisted single-wall connector on a residential solid-fuel appliance.
- Double-wall connector: product-specific, typically in the 6 to 8 inch range depending on whether you're measuring to a wall or ceiling.
- Listed wood stove: whatever the nameplate says. It takes precedence.
- Unlisted or antique solid-fuel room heater: generally 36 inches to unprotected combustibles.
Clearance is an air space, measured from the outside surface of the pipe, and it applies in every direction.
What clearance actually means
- Combustible means anything that isn't metal or stone. Framing, drywall, trim, sheathing, furniture, wiring, and building insulation of any kind all count.
- Measure from the outside of the pipe. Shasta Vent pipe has a 1-inch wall thickness, so a 6-inch inside diameter has an 8-inch outside diameter.
- It applies in all directions. Walls, ceiling, framing at penetrations, attic insulation.
- It has to stay an air gap. The required 2 inches cannot be filled with any material, combustible or otherwise. The air space is part of how the tested assembly manages heat.
Class A chimney pipe: 2 inches
Shasta Vent All-Fuel HT is ETL listed by Intertek to the HT requirements of UL 103 and requires a minimum 2-inch air-gap clearance to combustibles for pipe, elbows, tees, and any other component carrying exhaust gases. Clearance is a property of the listing, not the category, so if you're running a different system, read its label.
Where it matters:
- Ceiling penetrations. Frame to the dimensions in your product's table, not to a rule of thumb. Shasta Vent specifies a 12-1/4 inch square framed opening for the 6-inch Ceiling Support Box and 14-1/2 inch square for the 8-inch.
- Attics. Insulation drifts against pipe over time. An Insulation Shield is required where the chimney passes through an unenclosed attic.
- Roof penetrations. Verify 2 inches on all sides before flashing.
- Chases. Chase framing is combustible, and so is anything stored inside.
One nuance: inside listed penetration components such as a Ceiling Support Box, Firestop Radiation Shield, or Wall Thimble, the gap can be less than 2 inches because those parts were tested that way. That is not a general exception. Everywhere else, the full clearance applies.
Connector pipe: the bigger numbers
- Single-wall, unlisted, residential solid-fuel: 18 inches in all directions, per NFPA 211 and the model-code connector clearance table.
- Double-wall: listed at closer clearances, commonly around 6 inches to a wall, but only if the appliance instructions permit that distance. Use the number for the product you bought.
- A connector must not pass through a floor or ceiling.
- A connector must not pass through a wall unless it is listed and labeled for wall pass-through or routed through a listed pass-through device.
The stove itself
- A listed stove follows its nameplate and manual. That governs, not any general table.
- An unlisted or antique stove with no data plate is generally treated as 36 inches to unprotected combustibles.
- Whichever number is largest, stove, connector, or chimney, is what determines the layout. Plan the chimney around the appliance manufacturer's clearances.
Reducing clearances
Heat shields work, but only when built to the specification in your adopted code.
- The shield must be noncombustible and held off the wall by not less than 1 inch on noncombustible spacers.
- Edges must be open not less than 1 inch for air circulation.
- Spacers and ties must not sit directly opposite the appliance or connector.
- The protection must extend far enough that the protected path is at least as long as the original unprotected clearance.
- Clearance is still measured to the combustible surface, not to the face of the shield.
- Tile or brick applied flat to drywall provides no reduction at all.
Hard limits:
- A listed product's stated minimum cannot be overridden by a general reduction table.
- The IRC does not allow the reduction table to be used for solid-fuel appliances listed at 12 inches or less, or to reduce any listed solid-fuel appliance below 12 inches.
- The permitted reduction varies by protection type and by what's being protected. Look it up in the code adopted where you live.
More on the regulatory side in our chimney code requirements guide.
Going through a wall
Most modern through-the-wall installs transition to Class A at the wall and use a listed Wall Thimble rather than sending connector pipe through.
- The Shasta Vent Wall Thimble accommodates walls up to 10 inches deep, with a field-fabricated sleeve for deeper walls.
- The air space between the pipe and the inside of the thimble must not be filled with any material.
- The chimney must extend at least 2 inches into the room.
Details in planning a through-the-wall installation.
Clearance is not height
Clearance is distance from combustibles. Height is how far the chimney rises above the roof. Both have to be satisfied. Height follows the 3-2-10 rule: at least 3 feet above the highest point where the chimney passes through the roof, and at least 2 feet higher than any part of the building within 10 feet horizontally.
FAQ
What is the safe distance between chimney pipe and a wall?
Class A insulated chimney pipe is commonly 2 inches, measured as an air space from the outside of the pipe. An unlisted single-wall connector is 18 inches. Double-wall connectors are typically closer, per their listing.
What is the clearance for Class A chimney pipe?
Shasta Vent All-Fuel HT requires 2 inches in all directions. That comes from the listing, so verify the label on whatever pipe you own.
How far does a wood stove need to be from the wall?
Per the nameplate for a listed stove. Generally 36 inches for an unlisted or antique solid-fuel room heater.
Can insulation touch chimney pipe?
No. Building insulation of any kind must be kept out of the required clearance, which is why an Insulation Shield is required in an unenclosed attic.
Does a heat shield let me move my stove closer?
Sometimes, within limits. It must be noncombustible, spaced at least 1 inch off the wall on noncombustible spacers, open at the edges, and extended far enough past the appliance and pipe. It cannot take you below a listed product's minimum.
Do clearance requirements vary by location?
The technical basis is NFPA 211 and the model codes, but NFPA 211 is not itself law. It applies where a jurisdiction adopts it or an equivalent code, sometimes with local amendments. Your building department decides what applies to your project.
This article is general education, not installation instructions for your product, and not a substitute for your manual or local code. Clearance requirements vary by product listing, appliance, and jurisdiction. Improper clearances are a fire hazard. Follow the instructions supplied with your stove and chimney system along with the codes adopted where you live, and consult a qualified installer, a CSIA-certified chimney professional, or your local building official if anything is unclear
