I’m sure you seen one, but maybe you didn’t know the name of it or why it is there. I’m referring to that protrusion off the top of some buildings that almost appears to be a lookout for a fortress.

It’s called a cupola, and is pronounced kyou’puh luh. According to Wikipedia, “it is a small, most often dome-like, structure on top of a building. Often used to provide a lookout or to admit light and air, it usually crowns a larger roof or dome.”

If you are wondering where the idea came from, it can be traced back to 8th Century Islamic architecture. They were many times placed on top of a minaret, which is a tall slender tower that is part of a mosque.

Here is more about the history of the cupola:

Architectural History of The Cupola

Purpose of a cupola

Wikimedia Commons

These first cupolas placed atop minarets, were large and sometimes ornate structures with one or more balconies from which the daily call to prayer would be announced. These early cupolas are very significant because they are believed to be the inspiration for the dome which led to massive achievements in architectural design. These bold new designs that emerged, were used as symbols for proof of cultural superiority. During the renaissance, most major European cities and Islamic states were building a plethora of these magnificent buildings. The cupola had evolved to allow architecture to become a very artistic and creative status symbol and today, the cupola stands as a statement of a major achievement in architecture.

Read more here:  Architectural History of The Cupola

So basically, back in the day if you had cupola, you were the upper crust of the neighborhood. Eventually, cupolas became more common, though, and are as much functional as they are symbolic.

As far as the purpose of a cupola in roof design, they can act as a vent, allow more light into a structure, and serve as an observatory. They also help to provide insulation and add to the overall beauty of the building.

Many times you see them on churches, some having a bell to announce the service is beginning. There is a variety of cupola styles, and the one that is located in the International Space Station is quite impressive.

You can see a tour here:

Quite the view! I can’t imagine what that must feel like being 250 miles away from solid ground.

America’s first cupolas were first introduced during the post-Revolutionary period. They helped people tell one farm from the next because the cupola stuck up in the air high enough to be seen from a distance.

They have always been an aesthetic addition to any structure, but when you see them on a barn they are mostly utilized for light and ventilation. As mentioned, they allow hot air to escape and let cool air in, which can be a problem in barns, sheds, and sometimes a garage that don’t have much cross ventilation.

How do you know what size cupola is appropriate for a building? This post gives a general guideline:

How to Properly Size a Cupola

Function of a cupola

Wikimedia Commons

The old “rule of thumb” is:
‘For every foot of building width, you should have at least 1.25 inches of cupola’ .
So, measure the width of your building and times that by 1.25.

Example: 24 foot roofline
24 x 1.25 = 30
So your roof would require a 30 inch cupola.

Read the full post here:  How to Properly Size a Cupola

The above post also provides diagrams to help you visualize what size of cupola is needed. You can also talk to an architect or roofing contractor in Denver to find out how to go about adding a cupola to an existing property.