Quick answer: Shasta Vent Class A chimney pipe comes in 8", 19", 24", 39" and 48" lengths, in 6" and 8" diameters. There's also an adjustable section that covers 11" to 20". Each section adds 1" less than its listed length once installed. The pipe can't be cut, so order the mix that reaches your target height and use the adjustable section to fine-tune.
Ordering chimney pipe is a counting problem. Order too little and your install stops halfway, with the stove sitting cold until the next box arrives. Here's how to get it right the first time.
Every length and what it adds
|
Listed length |
Adds to the chimney |
Best for |
|---|---|---|
|
48" |
47" |
Most of the run. Fewest joints and quickest install |
|
39" |
38" |
Topping up a run without overshooting |
|
24" |
23" |
Mid-size gaps |
|
19" |
18" |
Short gaps and attic sections |
|
8" |
7" |
Small final adjustments |
|
Adjustable (11"–20") |
11" to 20" |
Hitting an exact height between fixed parts |
Why 1" less? Each section twist-locks into the next one, and the joint overlaps. Every joint also gets a locking band. No screws are needed, and screws must never reach the inner wall.
Why you can't cut Class A pipe
Class A pipe is a double wall of 304 stainless steel, with ceramic insulation packed solid between the two walls. The factory ends make the seal. Cut a section and you lose the joint and break the listing. When you need an in-between length, use the adjustable chimney pipe.
How to count your sections
- Find your finish height. The chimney must end at least 3 ft above where it passes through the roof, and 2 ft higher than anything within 10 ft. See our chimney planning guide for help measuring.
- Measure the Class A run. Measure from the top of the ceiling support box (ceiling installs) or the tee (wall installs) up to that finish height.
- Fill it with 48" sections first. Each one adds 47".
- Top up with a shorter section. Pick the shortest one that gets you to or past the target.
- Count the joints. Make sure there's a locking band for every one.
Example 1, through the ceiling: You need 12 ft (144") of Class A pipe. Three 48" sections add 141", which is 3" short. Add one 8" section (7") for 148" in total. Order 3 × 48" and 1 × 8".
Example 2, through the wall: You need 18 ft (216") above the tee. Four 48" sections add 188". Add one 39" section (38") for 226" in total. Order 4 × 48" and 1 × 39".
Going a few inches over is fine and still meets code. Coming up short is not.
Rules that affect how much pipe you need
- Support. A ceiling support box or tee support carries up to 50 ft of chimney. Taller runs need another tee support partway up.
- Wall brackets. Add an adjustable wall bracket at least every 10 ft along an outside wall.
- Above the roof. If the chimney rises more than 5 ft above the roof, brace it, and add support every 5 ft or less after that. See support brackets.
- Offsets. Each offset needs an elbow kit and changes your count. Measure along the angled run.
Frequently asked questions
What is the most popular chimney pipe length? The 48" section, because it covers the most height with the fewest joints. Most installs are mostly 48" sections plus one shorter section.
Can I mix 6" and 8" pipe? No. Match the chimney to your appliance's flue outlet and keep the same diameter all the way up.
Can I mix brands? No. A listed chimney is tested as a system. Use only Shasta Vent parts with Shasta Vent pipe.
How much clearance does the pipe need? A 2" air space to anything combustible, including building insulation. The full specs are in What Is Class A Chimney Pipe?
Ready to order?
Shop 6" and 8" Class A chimney pipe. Starting from scratch? A complete chimney kit covers everything but the pipe, so you only need to count sections. Shipping is free on orders over $75.
Disclaimer: This article is for general information. Every installation is different. Always follow the Shasta Vent installation instructions, your appliance manufacturer's instructions and local building codes, and check with your local building official. We recommend a qualified professional installer.
