What Is a Dormer? A Photo Glossary

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What is dormer?

Seven dormers and three chimneys on a 16th century Welsh roof
The roof of the Myddleton Arms in North Wales has 7 dormers, called The Eyes of Ruthin. Photo by LatitudeStock / Arcaid Images / Getty Images (cropped)

A dormer is a window that is typically set vertically on a sloping roof. The dormer has its own roof, which may be flat, arched, hipped, pointed, or ornamented.

A Window or Roof?

The dormers shown here, each having a gable roof, are from a pub called The Myddelton Arms. Located in the Medieval town of Ruthin in northern Wales, these notable and popular dormers from the 16th century are known as "the eyes of Ruthin."

For centuries, windows have been known as "the eyes" of a dwelling. Like a chimney, roof dormers are not part of the roof, but stick through the roof. Some dormers, called wall dormers, stick through the edge of the roof, the cornice.

Essentially, dormers are "glazed structures," meaning they are windows. In fact, they are sometimes called lucarne, a French word for "skylight."

To install a dormer in your home, call a window specialist and master carpenter instead of a roofer.

More Definitions of Dormer:

" dormer a glazed structure with its own roof that projects from the main roof of a building or is a continuation of the upper part of a wall so that the eave line is interrupted by the dormer."—John Milnes Baker, AIA
" Dormer Window. A window placed vertically in a sloping roof and with a roof of its own. The name derives from the fact that it usually serves sleeping quarters. Also called LUCARNE. The gable above a dormer window is often formed as a pediment and called a dormer head."—The Penguin Dictionary of Architecture

Explore the World of Dormers:

Dormer windows come in all shapes and sizes. They can be roof dormers or wall dormers. They can have different kinds of roofs, that may complement the larger roof or other architectural details of the house. Dormers can add beauty and curb appeal to your home, or they can end up making your house look ridiculous. The following photo gallery of dormers will help you make your own decisions.

Sources: "Dormer Window," The Penguin Dictionary of Architecture, Third Edition, by John Fleming, Hugh Honour, and Nikolaus Pevsner, Penguin, 1980, pp. 96-97; American House Styles: A Concise Guide by John Milnes Baker, AIA, Norton, 1994, p. 170

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Why a Dormer?

One story house near street, full width front porch, gable dormer
A single dormer can give a horizontal house a vertical lift. Photo by Phillip Spears / DigitalVision / Getty Images (cropped)

Dormers can have exterior and interior beauty and appeal.

On the inside, what may be dark, attic space can become habitable with a dormer window. An additional bathroom can be enlarged by a dormer tucked into a large bedroom. Besides additional space for a home, natural light and ventilation can make interiors more inviting and healthier.

From the outside, a dormer can define certain house styles—Neo-colonial and Colonial Revival, Stick Style, Chateauesque, Second Empire, and the American Foursquare are all house styles that generally include a dormer in their designs. Also, a dormer can give a horizontally-oriented house a sense of height, especially if the house is situated very close to a street. When designed correctly, a dormer can accentuate the architectural details in the body of the house—Victorian scrollwork, pediments, and even window likeness and symmetry can be enhanced by a like-minded dormer.

Trend to Avoid:

Like cosmetic cupolas that sit without function atop a roof, the false dormer is a growing trend especially in new commercial real estate. In an attempt to mimic a certain hometown colonial style of architecture, dormer units are attached to the roof without breaking through the roof. Fake dormers are usually out of proportion—either too large or too small—and they look ridiculous because they appear so unnatural. The artificiality of planned communities like Celebration, Florida is due, in part, to this type of fake architectural detail.  If you're tempted by this trend, ask yourself this—who are you trying to fool?

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Dormer = Dormitory

A bedroom inside a dormer.
A Bedroom Inside a Dormer. Photo by Image Studios / UpperCut Images / Getty Images

The word "dormer" comes from the same root as the word "dormitory," both coming from the Latin word dormitorium, which means a place for sleeping. It should come as no surprise, then, that attic spaces are often converted into extra bedrooms or originally built into large houses to accommodate live-in domestic workers.

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Add a Dormer Bathroom

A bathroom tucked inside a dormer
A bathroom tucked inside a dormer. Photo by Nicholls: Alistair / Arcaid Images / Getty Images (cropped)

Besides extra sleeping quarters, the additional interior space created by a dormer took a different turn with the invention of indoor plumbing.

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Gable Dormers

Cape Cod style house with two dormers on the house and one over the garage door.
Typical American Use of Dormers. Photo by J.Castro / Moment Mobile / Getty Images (cropped)

Dormers were especially popular in the 1950s Cape Cod style home designs of America's mid-century building boom. Nothing fancy with these additions—simple gable roof dormers that functioned as planned, adding light, air, space, and symmetry to the American home.

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Inside a Gable Dormer

Teenage girl digital tablet dormer alcove window seat
Additional glazing adds additional light to interior dormer spaces. Photo by Hero Images / Hero Images / Getty Images

The amount of light and ventilation afforded by a dormer is a function of the imagination. Do the windows have to match the other windows of the house? Can a dormer window be fancier? colored glass? nontraditional in shape?

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The Shed Roof Dormer

Long, low dormer atop a California Craftsman Home
Long, low dormer atop a California Craftsman Home. Photo by Thomas Vela / Moment Mobile / Getty Images (cropped)

After the gable roof dormer, probably the second most popular roof shape is the shed dormer. Often taking a pitch similar to the roof of the house, the shed dormer can accommodate small or large windows in a narrow or elongated width. Shed dormers are very common in Craftsman style homes and bungalows.

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The Extended Shed Dormer

Full Length Shed Dormer
Full Length Shed Dormer. Photo by J.Castro / Moment Mobile / Getty Images

Perhaps the most common type of shed dormer is the one extending nearly the full width of a house. In the front or back, this type of shed dormer extends interior space without adding to the footprint of the building. It has been very popular since the 1960s to the present time.

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Flat Roof Dormer on Modern Building

Flat Roof Dormers on Modern German Building
Flat Roof Dormers on Modern German Building. Photo by Andreas Secci / Passage / Getty Images

An extension of the shed roof dormer is the flat roof dormer. In this modern building in Germany, you can see that dormers are hardly an old-fashioned idea. Postmodern architects often take traditional architectural details and turn them on their heads.

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The Hipped Roof Dormer

Hipped Roof Dormer on a Stucco House
Hipped Roof Dormer on a Stucco House. Photo by J.Castro / Moment Mobile / Getty Images

The hipped roof dormer is slightly less popular than gable and shed dormers, but it's slightly more elegant. It often mimics the hipped roof of the house itself.

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Arched Eyebrow Dormer

Eyebrow Windows on a Thatched Roof in England
Eyebrow Windows on a Thatched Roof in England. Photo by Gillian Darley / Passage / Getty Images (cropped)

For centuries, the playful British have incorporated small arched windows into their cottage architecture. As these windows enable more light than space to enter interiors, eyebrow windows are often considered more window than dormer. The glazed slits can become very narrow and visually seductive.

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Mansard Roof Dormers

Dormers on a Mansard Roof
Dormers on a Mansard Roof. Photo by David Chapman / Getty Images (cropped)

Dormers are common features of Second Empire style homes. François Mansart (1598-1666) modified the gambrel roof by making the sides steeper and inserting windows. The French architect had invented what became known as the Mansard roof. These windows breaking through the Mansard roof are some of the earliest examples of dormer windows.

Even a more modern building with a Mansard roof likely will have dormers—sometimes both wall dormers (through the cornice) and roof dormers. The elegant and regal Biltmore Estate in Asheville, North Carolina exemplifies the 19th century Mansard roof dormer on a Chateauesque style large home.

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Through-the-Cornice Dormers

Through-The-Cornice Dormers
Through-The-Cornice Dormers. Photo by J.Castro / Moment Mobile / Getty Images (cropped)

Most dormers are roof dormer windows—that is, the structure's roof surrounds the dormer as if it were a skylight. Accounting for snow loads in certain climates, constructing roof dormers is relatively straightforward in both original design and renovations. 

A more complicated and some would argue a more elegant design is the dormer that is built through the cornice, or the roof's edge. Also called wall dormers, these "through-the-cornice" dormers are common in grand mansions and upscale neighborhoods.

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An Architect's Eye for Windows

Window Varieties in a Mansion Home Designed by Paul Williams
Detail of a 1927 Southern California Home Designed by Paul Williams. Photo by Karol Franks / Moment Mobile / Getty Images (cropped)

Windows are part of an architect's toolbox. In this Southern California house, the renowned Paul Williams (1894-1980) combined different window types in an aesthetically pleasing way. A shed dormer and a wall dormer breaking through the roof line are added to more typical windows and an oriel window to make this English Manor style "cottage" look like a simple country home inside and out.

Remember that a good architect will have the education and training to envision design patterns that work for your house.

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Installing Prefab Dormers

A prefab dormer is installed with a crane on a roof
A prefab dormer is installed with a crane on a roof. Photo by Jaap Hart / E+ / Getty Images

Not everyone has the funds to hire an architect the likes of Paul Williams to design your home. Not to worry. Adding a prefabricated dormer to an existing home is an exciting adventure. Consider the challenge, but do your homework.

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The Eyes of Your House

Two eyebrow window dormers in a red tile roof
Eyebrow Windows. Photo by Marco Cristofori / Corbis Documentary / Getty Images

Remember that essentially dormers are windows, and glazing is two-faced. Whether you are looking out or the neighbors are looking in, dormer windows can make your home come alive. Just look at those eyes....