Not many architectural features can be spotted on both the domes of Renaissance cathedrals and the roofs of rustic barns. But that odd versatility is just one of the many things that make cupolas so unique. In centuries past, cupolas provided ornamentation, ventilation, natural light, and broad rooftop views. Today, they’re most often installed for their curb appeal, period style, and climate control capabilities. If you’re considering a cupola for your home or outdoor structure, here are some of the important things you should know before you raise the roof.
Pronounced kyoo-po-la (“kyoo” as in cue ball), the word cupola derives from a Latin word meaning a little cask or small vault. Architecturally, it’s a diminutive dome-like structure rising above a roof or dome, though the word sometimes refers to a dome-shaped roof or ceiling itself.
Cupolas have been used for many centuries to decorate both public and private structures. They’re commonly found atop places of worship—most famously for Westerners, Italian Renaissance cathedrals such as the Basilica di Santa Maria del Fiore, aka Florence Cathedral, home of the famous Brunelleschi’s Dome.
In domestic architecture, cupolas are associated with period styles such as English or French Country, the Victorian era’s Italianate style, or in the U.S., American Colonial or Colonial Revival houses. Besides homes, they’re also commonly built on dovecotes, gazebos, sheds, garages, and barns (often with a weathervane and/or finial).
By allowing air to rise and escape, a cupola can help prolong the life of a building’s roofing materials while making the interior more comfortable. This is a great option for getting hot air out of an attic, which will help lower your cooling bill in summer.
Lantern-style designs are a particularly bright idea for bringing warm natural light into large stairways and windowless hallways, as well as attics, garages, and other rooms.
For period-style homes, a cupola is an authentic architectural detail that instantly creates a homier, more traditional curb appeal. Contemporary styles and all-weather materials have also increased the cupola’s usefulness as a finishing touch for modern homes, garages, and backyard buildings.
A cupola consists of a base, a mid-section with louvers or glass, and a roof. Many are square, octagonal or hexagonal in shape. The louvers function as vents, and can help keep out pests or insects if used in conjunction with screening. Most cupolas are designed for finial and/or weathervane compatibility.
Apart from basic shape or louvers vs. glass, another feature to consider is the cupola’s roof design. Most are pyramidal or bell-shaped (aka belltops) and constructed from metal, even if the base and mid-section are vinyl. Some pyramid roofs have a straight 45-degree angle, but many have more concave lines or even a swooping, almost pagoda-like slope.
A peak rooftop position makes cupolas highly visible, but it also provides constant exposure to the sun, wind, and elements. Fortunately, the materials used to make them are as hardy and durable as they come.
Vinyl is the most common cupola material, built from the same material as fences and garden arbors. They’re maintenance free, moisture resistant, and virtually impervious to weather and wear. They’re typically white in color, with UV protection to guard against fading, and can be painted to match your home.
Unfinished cedar, cypress, and other woods provide a crafted look, and give you more options if you want a particular color or finish. These materials come unprimed or primed and ready for painting or staining.
Copper and aluminum are the two most commonly used metals. Of the two, copper is the most traditional. Left untreated, it weathers to a beautiful light green/gray color as it ages.
Finding the best cupola size for your home is a simple matter of proportion. Manufacturers and professional installers recommend using a ratio of cupola base width to unbroken roofline—typically a minimum of one inch of cupola to every one foot of roof. For multi-story buildings, a ratio of 1.25+/12 inches is preferable. Measurements below represent a cupola for a 24 foot roof line. Use it as a reference, substituting the true dimensions of your unit. Brands such as Good Directions recommend about 1.5 inches of width to every foot of uninterrupted roof line (i.e. roof width minus the cupola width).
A better option for some architectural styles and longer rooftops is to double up, positioning two smaller cupolas atop the roof rather than a single large one. This creates an appealing visual symmetry, and provides better ventilation and natural lighting.
Before installing a cupola, you’ll need to determine the roof pitch. To do so, nail two thin boards together at one end so they can pivot. Set the boards so they straddle the roof peak, with each side flat and the peak touching the point of intersection. Mark a pencil line where the boards cross each other, and use this as a cutting template to mark and cut the roof angle on the cupola base box.
Ornamental cupolas should be relatively easy to install if you follow the manufacturer’s instructions. If you plan to use yours for ventilation, you’ll need to cut a vent hole along the roof peak. This opening should be six inches smaller than the cupola width, i.e. when cutting down on either side of the peak, leave at least a three-inch border of roofing material between the vent hole and cupola base interior. Most importantly, cut only the shingles and roof sheathing, not structural elements such as the ridge or rafters.