A well-placed dormer turns a dark attic crawl space into a usable bedroom, home office, or playroom. The wrong style can ruin a roofline and tank curb appeal. Understanding dormer window styles matters as much for aesthetics as for code compliance and waterproofing. From the simple shed dormer that adds the most usable floor area to the elegant eyebrow dormer that defines historic homes, each type has specific use cases, costs, and structural considerations.
- What a Dormer Actually Does Structurally
- Style One: Gable Dormer (The Classic)
- Style Two: Shed Dormer (Maximum Floor Space)
- Style Three: Hip Dormer
- Style Four: Eyebrow Dormer (The Showpiece)
- Style Five: Wall Dormer (Integrated Look)
- Style Six: Bonnet Dormer
- Style Seven: Lucarne Dormer (Tall and Narrow)
- Window Choices for Dormers
- Roofing and Flashing Considerations
What a Dormer Actually Does Structurally
A dormer is a vertical extension that projects from a sloped roof, framed with its own walls and roof, with a window in the front face. Adding a dormer requires removing rafters or trusses, installing a structural header, and rebuilding the roof intersection with new flashing and underlayment. Standard pricing in 2026 runs $4,000 to $12,000 for a small bump-out and $15,000 to $30,000 for a full shed dormer across the back of a house.
Most municipalities require permits for any dormer work. The IRC mandates that headroom in habitable attic spaces meet a minimum of 7 feet over 50 percent of the floor area where the ceiling height exceeds 5 feet. That single rule drives most dormer-sizing decisions.
Style One: Gable Dormer (The Classic)
A gable dormer has a peaked roof that runs perpendicular to the main roof. The triangular face holds the window. This is the most common residential dormer in American architecture, especially on Cape Cod and Colonial style homes.
Pros: relatively simple framing, sheds water well, traditional look that suits most colonial-influenced homes. Cons: adds modest interior space, can look busy if multiple gable dormers crowd a small roof. Typical cost per dormer: $5,000 to $12,000 installed with a vinyl or fiberglass window from Andersen, Pella, or Marvin.
Style Two: Shed Dormer (Maximum Floor Space)
A shed dormer has a single-pitch roof that slopes in the same direction as the main roof but at a shallower angle. Because it can run nearly the full length of a roof slope, it adds the most usable floor area of any style. Most modern attic conversions use shed dormers.
Pros: maximizes ceiling height and floor area, allows for multiple windows side by side, cost-effective per square foot of added space. Cons: low pitch (often 2:12 or 3:12) requires self-adhering ice and water shield in cold climates and special roofing materials. Typical cost: $15,000 to $30,000 for a full-width shed dormer across the back of a 30-foot house.
Style Three: Hip Dormer
A hip dormer has a roof that slopes on three sides, meeting at a peak. The window sits in the vertical front face. It looks more refined than a gable dormer and integrates particularly well into homes that already have hip-style main roofs.
Pros: sheds water and snow excellently, lower visual profile than a gable, less prone to flashing failure. Cons: more complex framing, smaller window opening, higher labor cost. Typical cost: $7,000 to $14,000 installed.
Style Four: Eyebrow Dormer (The Showpiece)
An eyebrow dormer is a low, gently curved bump in the roof line with no vertical sidewalls. The roof flows continuously over the top, creating a soft arched window opening. It is most associated with Shingle Style, Craftsman, and certain Victorian homes from the late 1800s.
Pros: stunning architectural feature, adds character without dominating the roofline. Cons: extremely expensive due to custom curved framing, limited to small fixed-glass or specialty windows, slow roofing labor. Typical cost: $15,000 to $40,000 per dormer. Brands like Marvin and Andersen offer custom curved units, but they often require 12 to 16 week lead times.
Style Five: Wall Dormer (Integrated Look)
A wall dormer extends the existing wall plane up into the roof rather than projecting outward. The face of the dormer is flush with the building’s exterior wall, blending the second-story window into the facade. Common on Tudor, French Country, and many farmhouse-style homes.
Pros: clean integration with existing facade, structurally efficient, easier flashing where the dormer meets the wall plane. Cons: requires careful architectural planning to look intentional, may require relocating gutters. Typical cost: $8,000 to $18,000.
Style Six: Bonnet Dormer
A bonnet dormer is similar to a hip dormer but with a rounded or arched roof rather than three flat planes meeting at a peak. It is sometimes called a segmental dormer. Historic homes in New Orleans and parts of New England use this style.
Pros: distinctive curved profile, sheds water well, looks elegant on the right architecture. Cons: custom framing required, limited supplier base for curved roofing materials. Typical cost: $12,000 to $25,000.
Style Seven: Lucarne Dormer (Tall and Narrow)
A lucarne is a tall, narrow dormer typically capped with a steep gable. Originally medieval European, it shows up in American Gothic Revival and some Queen Anne Victorians. The narrow window often features stained or leaded glass.
Pros: dramatic vertical accent, suits steep-roof historic homes. Cons: niche application, can look out of place on modern designs, often needs custom millwork. Typical cost: $10,000 to $20,000.
Window Choices for Dormers
Most dormers use casement, double-hung, or fixed windows. Casement windows from Andersen 400 Series or Pella Reserve work well because the crank operation suits hard-to-reach attic locations. Double-hung windows look more traditional but require room to slide the lower sash.
Egress requirements drive sizing for bedroom dormers. The IRC requires a minimum clear opening of 5.7 square feet (with a minimum height of 24 inches and minimum width of 20 inches), and the sill cannot exceed 44 inches above the floor. A standard double-hung egress window typically measures 30×60 inches or larger.
Roofing and Flashing Considerations
The intersection between a dormer and the main roof is the most common leak point. Step flashing along the sidewalls and a continuous head flashing at the top are non-negotiable. In northern climates, a 36-inch wide ice and water shield underlayment is required by code along eaves and around dormers.
Asphalt shingle dormer roofs typically last 20 to 25 years. Standing seam metal (29-gauge from McElroy or Englert) can last 50 years and works particularly well on low-slope shed dormers. Expect to pay $8 to $14 per square foot installed for asphalt and $12 to $20 per square foot for standing seam metal.
