A Quick Guide to Measuring Your Flue or Chimney Crown

Measuring your flue or chimney crown is crucial to ensure a proper fit for your chimney cap. But what exactly do you need to measure? What is the difference between a chimney crown and a flue tile? It can seem daunting with so many flue shapes and chimney types, but we'll give you everything you need to make it streamlined and straightforward.

What Is a Flue Tile? Or a Chimney Crown?

First, let's discuss the difference between a flue tile and a chimney crown. It might initially seem complicated, but it is an important measurement distinction.

A flue tile is the top end of a masonry chimney's ceramic line. It may extend above the rest of the chimney, acting as a "lip." Not all flue tiles extend like this; instead, they end inside the chimney crown.

Meanwhile, the chimney crown is simply the top of your chimney. This is the slab itself on which the chimney cap will rest and protect the opening to your chimney. Often, these can be white or off-white, but they will vary with your home.

Now, we'll talk about what measurements are needed for each type of chimney cap.

Mount Type

• Surface Mount (Single Flue or Multiple Flues): Surface-mounted caps need your chimney crown's outside width and depth and the listed flue dimensions.
• Tile or Chimney Pipe Mount: These mount types will only require the dimensions listed below for your flue type.

Masonry Chimneys

• Single-Flue Chimneys:
  • Round Flue: The required measurements depend on whether your chosen cap slips into the flue or fastens to the exterior.
  • Slip-In Caps: You will only need to measure your inner flue diameter.
  • Exterior Caps: You will only need to measure your outer flue diameter.
  • Square or Rectangular Flue: The required measurements depend on your chosen cap.
  • Top-Mounted Caps: For top-mounted caps, measure the length and width of your entire chimney, the length and width of the area that encompasses your flue, and your flue height.
  • Caps with Legs or Brackets: Measure the width and depth of the outside of your flue.
  • Extended Square or Rectangular Flue: These flues require the outside width and length measurements.
  • Flexible Liner: You will only need to measure the inner diameter.
  • Oval Flue: For oval-shaped flues, measure your flue's outer length and width.

• Multi-Flue Chimneys: Multi-flue chimneys require the length and width of your chimney, the length and width of the smallest area encompassing all flues, and the height of your tallest flue.
• Square or Rectangular Chimney Cap and Damper Combinations: For these combinations, you will need to measure the inside length and width of your flue.

Factory-Built Metal Chimneys:

• Single-Wall: You will only need to measure your outer pipe diameter.
• Double-Wall: Measure your inner and outer pipe diameter.
• Triple-Wall: Measure your innermost and outermost pipe diameter.

Next, we'll discuss the mesh size for your chimney cap. Follow the link to the next step! For more helpful times or additional information, feel free to check out our in-depth Chimney Cap Measuring Guide.