As architectural styles have shifted, architects and builders have invented more ways to build dormers, the little rooms that project from a roof and allow more space and light in the top floor or attic.
Arched top dormers often point to architectural styles that originated in France. These include the Second Empire style (popular 1855-1885), named for the period when Napoleon III ruled France; the Beaux Arts style (1885-1930), favored by Americans who had studied at the leading French school of architecture, Ecole des Beaux-Arts; and the French Eclectic style (1915-1945), based on traditional French houses.
With their curiously curved roofs, eyebrow dormers frame views from houses of several architectural periods, including the Shingle style houses popular in East Coast seashore communities. Eyebrow dormers are also used on houses where the roofing shingles are curved around eaves to mimic the look of thatch.
Gabled dormers have a peak at the top and a roof that slopes downward on either side. This is the most common type of dormer. The design works well with a wide array of architectural styles, including Queen Anne Victorian, Tudor and Craftsman. Gabled dormers are also found on Colonial Revival and Gothic Revival houses and on houses in the French Eclectic style.
This is basically a gabled dormer, but the dormer roof flares out in the same way that the main roof on a house often flares out to accommodate a porch or an addition. On the dormer, the flared roof helps shade the windows, a boon when dormers face south or west in regions where summers are hot. Intricate corbels support the overhang of the roof.
Pedimented dormers are similar to gabled dormers, but they incorporate details rooted in classical architecture. In ancient Greece and Rome, buildings often had a row of columns across the front. They supported a horizontal beam that held up a triangular wall, known as the pediment, that was under the roof peak. On pedimented dormers, molding emphasizes a similar triangular shape. Vertical molding on either side of the windows stands in for columns.
A shed dormer (visible behind the peaked roof on the house shown here) has a roof that slopes in only one direction, toward the front. Many freestanding sheds have roofs that look similar, hence the name of this style of dormer. Dormers in this style are characteristic of Dutch Colonial, Craftsman and Colonial Revival houses.
Fit into a steeply pitched mansard roof, this shed dormer sits almost flush with the surrounding slates. Mansard roofs are similar to hip roofs except that each side has two parts: a steep section near the walls and a barely slanted section toward the middle of the building. This creates an attic that's fully usable, so it's probably no surprise that dormers often are found on mansard roofs.
On a hipped dormer, the roof slants back as it rises, and this occurs on the front as well as on the sides. Hipped dormers, not surprisingly, are often found on houses where the main roof is hipped as well. This style of dormer is common on houses in the Prairie, French Eclectic and Shingle styles.
When a hipped dormer projects from a roof at a 45-degree angle, it takes on a pyramidal shape. This design is unusual but creates an opportunity for a nearly wrap-around view because there are spaces for windows that look out in two directions.
Recessed dormers, also known as inset dormers, have one or more walls that are set into the roof, rather than placed on it. This style of dormer allows the windows to be deeper than they might otherwise be.
Polygonal dormers are similar to octagons, except that the back three sides are absent. Because they look out from five directions, they offer a superlative view. On this house, the polygonal dormer on the lower roof teams up with smaller hip-roof dormers that have slanting sides.
Wall dormers aren't surrounded by roof, as most dormers are. Instead, as their name implies, they rise from a wall. Except for this feature, though, they span the full range of dormer styles, from arched top to shed roof to hip roof. Wall dormers are found in houses of many styles, including Gothic Revival, Romanesque and Mission.