Curious about recommended roof pitches in a riding arena? Senior architects John Blackburn and Ian Kelly advise that:
A 4:12 pitch is pretty much our recommended minimum on any horse structure. We prefer steeper roofs for a natural chimney effect. However, unless you live in a cold climate where there is a lot of snow, we wouldn’t advise going taller than 6:12.
The numbers indicating a 4:12 roof pitch mean the roof rises 4 inches in height for every 12 inches, as measured horizontally from the edge of the roof to the centerline.
Okay, so for barns our rule of thumb is as steep as you can make it. The steeper roof allows the Bernoulli principle and chimney effect to work more efficiently and effectively. But there are other considerations in designing the slope of a barn or arena roof.
For arenas, steeper the roof = the taller the building. This impacts the look or mass of the arena on the property which can be negative. It can stick out like a sore thumb or look like an airplane hangar in your backyard.
Because we depend less on natural ventilation in indoor arenas than in barns, we can get away with lower slope roofs. However, we don’t recommend lower than 4:12 if at all possible. We realize some HOAs and neighborhoods have severe height restrictions and the wider the arena, the more difficult it is to comply without “flattening” the roof. At Winter Farm in Peoa, Utah, we designed a low roof to stay within an imposed limit. In some areas, arenas may be considered agricultural buildings and therefore exempt from height limits. But that rule isn’t consistent across state lines or jurisdictions. For example, in one jurisdiction we were permitted a covered arena as a “sun shelter” and avoided building height limitations entirely.
Because arena walls at the perimeter are usually 16’ tall (need head clearance for horse and rider on interior below the structural frame), when the roof is a low slope, the roof becomes less visible as you get closer to the building and the building can look like a huge box.
You can make a huge box look great but that may require a lot more money and you typically want the arena to be in the background. The barn and the farm are the main focus and not that big ugly box on your farm.
One way we reduce the impact of the arena size is by pushing it into grade where we can, using the land contours and landscaping where possible, and placing it behind the barn and other structures to reduce the scale of the building.
Probably the best average height for a barn is 6:12 to 7:12. The reason is it is more difficult for a roofer to walk on a steeper roof without some sort of support. Thus the installation time increases dramatically as will the cost if it is built with a steeper roof.
One of the down sides for low slope roofs in snow climates is snow loading. A steeper slope can be designed to shed snow pack better than a low slope but the downside for that is the avalanche effect. When it melts it can fall fast, be loud and block doorways… a subject for another blog post!