What Size Cupola and How Many?

Pole Barn Guru Blog

What Size Cupola and How Many?

In the world of post frame (pole buildings) cupolas are relatively small, usually square, structures placed on top of the ridgeline. While they are primarily aesthetic, with side louvers they can also be functional vents.

The cupola is a development during the Renaissance of the oculus, an ancient device found in Roman architecture, but being weatherproof was superior for the wetter climates of northern Europe.

CupolaMy own and only personal cupola experience is with the one mounted on the top of our post frame house along the South Dakota side of Lake Traverse. Our building has a footprint of 4824 square feet and the peak of the roof is 44 feet above grade. We put a four foot square cupola with glass sides on ours, with four pairs of different colored lights so they can be changed depending upon the season. My bride has far too much fun changing the bulbs to match her mood….er I mean the season!

Now there is a “science” (keep in mind, it was created by a cupola manufacturer who wants to sell more and larger cupolas) to cupola selection.

To select the “right” size cupola for a building, a good rule of thumb is 1.5 inches of cupola for every foot of unbroken roof line (measured along the ridge). Using this theory a 24 inch cupola would only be good for 16 feet of ridge line, 36 inch would cover 24 feet, and 48 would do 32.

For ridgelines greater than 32 feet, they recommend an inch of cupola for every foot of ridge. This would place two 24 inch cupolas on a building up to 48 feet long, two 36 inch for 72 feet and two 48 inch for 96 feet.

In my humble opinion, the two cupola sizing seems much more realistic than the single cupola.

I had always been educated to size the cupola to the building width, where cupolas were most often sized with an inch of cupola for each foot of building width across the gable end.

In the end, beauty is in the eye of the beholder – see a cupolaed building you like the looks of? Email it to your Hansen Pole Buildings’ Designer to get sizing and quantity ideas which will meet your needs and budget.

6 thoughts on “What Size Cupola and How Many?

  1. Ally Saltonstall


    I have a 40×60 pole barn for my horses and am looking to add a cupola or two for ventilation. I am unsure of what size would be appropriate. Any help would be greatly appreciated!

  2. Sanford Holden sr

    I have a 60 by 100 by 20 foot high to the bottom of rafters pole barn for hay storage.
    I’m looking to put vent fans in some cupolas to create airflow I’m interested in your opinions on what size and how many.

    1. admin Post author

      I would probably start with two 48″ vented side cupolas spaced evenly on your 100′. You might get enough exhaust from them alone to avoid having to add powered fans.

  3. We are building a barndominium to look like the original old barn on our farm. We have one problem and that is we have a fireplace that doesn’t come in the center of the ridge line. We were wondering if we could still cover it with a cupola even though it’s not centered.

    1. Could you? It is possible, although it is likely to look strange. You would also have to either build it onsite, or (if using a prefabricated cupola unit) create a base to support it being not centered upon the ridge.


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