Different barns have different designs for the roof. There are lots of different cupola styles. What was the function and purpose of a cupola to begin with? Why the differences between barn styles and regions of the country?

I always figured a cupola was for ventilation. As for the differences in barn styles, I think that answer is book length! I'm sure others can offer more insight but I'd say a lot of the design evolved from tradition (German immigrants brought German barn design, Dutch immigrants brought Dutch barn design etc.) combined with the fact a barn is a very utilitarian structure. So regional differences evolved from specific use and climate variations. There are a lot of good barn books out there and several that focus on whatever region in which you may reside.

They are just to vent the barn. They don't do a very good job unless they are HUge. Mostly they are just "pretty" and every carpenter has diffent ideas about what works best.

The vented sides allowed the hot air out.

They were part of the roof not stuck on top of the roof.

A place to mount the weather vain.

The primary purpose of a cupola is ventilation. It may also let in limited light.

Some curved rafter barns had ventilation ducts that ran from the ground level to the cupola. The ducts were made by boarding up the bottom side of the rafter. This allowed a draw from the livestock level to the cupola without the air going through the mow.

Neal

The function of the cupola on my old gambrel roofed barn is for ventilation and ornamental. Mine has a weather vane that indicates wind direction and a jaunty horse atop the vane.

There are many styles of barns. Ours is built on a slight hillside and has a drive in door into the haymow. Stanchions are below as well as pens for calves and horses. This area also had many round barns built in the 1920s. The central and eastern part of Wisconsin has some barns build of native limestone. Fascinating subject. What kind of barn do you have?

When I built my octagon barn 14 years ago I built a cupola on it. 4 side have vents that have doors to close in the winter and open in the summer. I have walk in doors on 4 sides of barn no matter where the wind is coming from it cools the barn. The other 4 sides of the cupola have solid windows to let in light.

I read recently that the smaller English barns in Maine with the doors in the sides were mostly for farmers growing for their own needs. You drove a wagon in and unloaded to either side. You still see a few around. The much larger dairy barns which mostly load through the ends (thus a shorter poke to the back wall) went up in the late 1800's, when railroads made it possible for farmers here to ship milk to the city. Farmers started producing commodities in amounts way beyond their own needs, instead of just selling surplus. Needed more room for hay, cows, and manure down below.

Carlheth, it would great if you could post a few pictures of your barn.

Besides ventilation I have used mine for safer access to the roof for repair I have a 24ft step ladder in my loft I use it to get up their remove the vent and tie off to beam for my loft trolley it seems safer than trying to go up from the outside as my barn built in the early 1900s which I live in now has an extremely steep roof

Here in Ky. The old barns were either a strait pitched roof if you raised tabacco or octagon type for hay and livestock. Built for what you needed.

I have a Jamesway catalog from the late teens/early 20's that shows how a proper cupola works and the ventilation ducting that goes with it. At least it's how Jamesway would have liked you to do things. Quite an involved process but in the pre-electric fan days I bet it worked better than anything else. The math involved for figuring the sizing of the system was pretty involved.

Bill, would there be some way you can share the information in your catalogue? How did they go about calculating and figuring requirements?

One of the reasons I am so interested in how things "used to be" and keep coming back here, is because I wonder how much knowledge have we lost because it was "common knowledge".

I'm not tech savvy enough to do that. But I've sen the same catalog on Ebay for $10.00. Might start watching there.