Chimney Height: The 2 foot, 10 foot, 3 foot Rule


Folks often have trouble grasping the 2 foot, 10 foot, 3-foot standard. These chimney height measurements are important to meet building requirements. Positing a chimney on the home relative to the rest of the home may cause it to draw better. This will generally cause you fewer problems as a homeowner.

Chimney Height

What is the 2 foot, 10 foot, 3-foot rule? The chimney must extend at least 3’ above the highest point where it passes through a roof. And at least 2’ higher than any portion of a building within 10′. Specifications aren’t there to merely cause you problems. They intend to make sure that the chimney draws properly and that a fire hazard does not occur. If, however, the manufacturer of a factory-built fireplace unit, wood stove, or other appliance has other specifications, these must be followed.

Any peak that is within 10 feet of the chimney can compete with the chimney. This can cause draft problems. This is why the rule calls for the chimney to extend 2 feet above any structure within 10 feet of the chimney. If your home is at a particularly high altitude, I recommend consulting a professional in your area when it comes to these particular specifications. The high altitude and thinner air can possibly cause necessary measurements to differ slightly.

Draft problems are often due to many things!

Chimney draft problems are often due to chimney height or lack thereof. But just as critical is negative pressure issues in the house that cause sluggish drafts. These can include installation of new attic insulation, powerful roof vents, cathedral ceilings, large stairwells, and fans in kitchens as well as bathrooms. Even the addition of new storm windows can change the air balance in the house. Additionally, cold air vents across the fireplace on the wall are notoriously for being sluggish with the draft.

Click here to read more about smoking fireplace problems.

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Clay Lamb
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61 thoughts on “Chimney Height: The 2 foot, 10 foot, 3 foot Rule

  1. Steve thank you for this correction. That’s awesome. Appreciate you for the correction. It’s interesting how just a couple of letters can change the whole paradigm. Thanks for providing that link and illustration. Hats off to you for providing that description and visual illustration from Vermont Castings. Heck, you even gave us a page number!


  2. I need to know how high the chimney is, but too leery of getting on ladder to measure it. House is 2-story, so I am guessing it to be 30′ feet? Want to have siding installed, chimney measures 28″ D twice and 61″ W. Trim will be
    5″ on both sides of width, but not necessarily any on short sides. I am ordering materials for 20×30 addition and
    chimney this week.
    Can you help, please??? 404-642-1421 Thank you.

  3. Let me start off each, level of brick or row is called a coarse, count 9 coarses that equal 2 foot. If you’re trying to figure how long something is, see if you can measure at the base or count bricks in each brick is about eight inches wide. I would like to address your statement of citing the the chimney. I’m not sure why or how or if it would even be acceptable. That would dependent on the substrate below being wood brick or block. Consult with your contractor before making this investment.

  4. Hi,

    I have seen fireplaces (prefab boxes) on new homes that do not have a chimney up the side of house but rather stop just 3-4 ft above the box. I have always had water leakage where chimney goes through edge of roof and would like to just eliminate the chimney all together. Thinking about purchasing one of these. Any comment on these fire boxes?

  5. To me this sounds like a vented gas fireplace system because of the smaller height. I would only recommend you look up the manufacturer’s installation requirements before you purchase one. Let’s address that current water problem: it sounds like it may be a chimney chase cover problem. The chimney chase cover needs to be stainless steel and properly pushing water away from the chimney. I attached this video for further information.


  6. How can the chimney chase be checked to see if the proper sheetrock exists? Should that sheetrock be 5/8″? Should the interior of the shaft be lined with insulation? We are told all the fireplaces are improper in our condo complex and the shaft needs to be lined with 5/8″ sheetrock? OR we can convert to gas. This seems like a building code issue.

  7. Its all based on your building codes and the AHJ, the the authority having jurisdiction, as well the chimney venting pipe manufacturer. I call this being got between a rock and a hard place. Also my first approach would be to pop the chase cover at the top to explore whats down inside there.

  8. Wow, there’s some great and informative info here. Q ? Son’s house in Dormont (inside Pittsburgh) has two fireplaces. One is on an outside wall, but is old school built, as in1935. The inner fp also has a roof top chimney. Now, his intention is to convert both to gas. He must repair the chimney on the inner fp, but since it’ll be gas, does the chimney have to be a min of three feet tall. Also, if the outside wall fp will be modernized to have an outside vent, can he demolish that chimney?

  9. I am designing a single chimney for multiple fireplaces. I have done a bit of research and have found out how large the flue needs to be for each fireplace and that it is best to have one flue per fireplace, one fireplace per flue. I also know that a single fireplace can have multiple flues. What I cannot find out is how much chimney I need per flue, not height, but the two horizonal distances. An example, I have a chimney with three flues each 78.5 square inches. How big would the chimney be? How thick would the chimney walls need to be and how much space does each flue need?

    Thank you for any assistance.

  10. You may want to check just a little more, as I have not seen anything that doesn’t require that every fireplace or appliance in any given chimney chase, must have it’s on own separated and properly sized chimney venting system.
    Clay Lamb

  11. I will say since I don’t have boots on the ground there. I going to be careful about this question. I would personally check with the manufacture or written instructions of the gas logs, as well as a local or bldg inspector.

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