How Much Does It Cost to Add a Dormer? (2023 Guide)

Dormers bring light and space to your home’s interior while increasing curb appeal. Adding one to your home is a major undertaking, and installation costs are wide-ranging. Prices depend on the dormer’s type and size, but you can expect this project to cost around $24,000.* 

We at the This Old House Reviews Team have outlined the various costs required to add dormers to your home’s roof so you can make an informed decision before contacting a local builder with your plans.

*All cost data sourced from Angi.com and HomeAdvisor.com.

A dormer is a roof structure—usually containing a window–that adds architectural interest to your second floor or attic space. These are typically triangular and situated on the roof’s slope, protruding from its plane. A dormer provides additional living space as well as increased natural light and ventilation. 

Not all dormers are alike. Types of dormers include gabled dormers, shed dormers, hipped dormers, and more. Gabled dormers are triangular and project vertically from the roof. Shed dormers are rectangular and project horizontally. Hipped dormers project at an angle that allows rain to run off easily. 

Each dormer type has unique benefits. For instance, a window dormer operates like a skylight, flooding a room with natural sunshine. Certain home styles are more likely to feature dormers. These include neocolonial, châteauesque, American foursquare, and Second Empire. 

Dormers come in at least a dozen different styles. The most common dormer types are gable dormers and hip dormers. Gable dormers have the same angle as the roof, while hip dormers are angled at 45 degrees. There may be additional installation costs to consider, depending on your roof’s style.

*Smaller than traditional dormers.

Arched Top Dormer Cost

Arched top dormers first appeared on 19th-century French homes. They jut out from the house and have a curved, sloping roof with an arch at the top. Arched-top dormers come in square, rectangular, or semi-circular shapes. They can cost $25,000–$37,500, depending on the construction material used. 

Eyebrow/Eyelid Dormer Cost

Both functional and beautiful, eyelid dormers have been part of American architecture since the 19th century. These distinctive dormers have a low profile with no sides and roll in a wave-like pattern over a window. Eyelid or eyebrow dormers are especially popular in traditional, high-end coastal architecture and usually cost $26,250–$40,000. 

Flat Roof Dormer Cost

Like its name suggests, a flat roof dormer has a flat roof and is built out from the main roof. This type of dormer has a more traditional aesthetic and can be used to create bedrooms, living spaces, or even home offices. A flat roof dormer doesn’t require any structural changes to your house and costs $20,000–$31,250.

Gable Dormer Cost

Gable dormers are likely what come to mind when you think of a dormer. They feature slanted sides and peaked tops. Many homeowners love them because they make spaces feel larger and create more natural light. These dormers can be simple to build, so they may cost less than other types. Depending on size, framing details, and other architectural factors, your budget for a gable dormer should be around $32,500.

Hipped Dormer Cost

A hipped dormer slants back on the front and sides and is most commonly found on hipped roofs. It can be installed as a home addition or built into an existing roof line. The cost for this dormer type is around $31,250. 

Shed Dormer Cost

Shed dormers typically appear on Craftsman, Dutch Colonial, or Colonial revival houses. You can install a shed dormer as a wall extension or from the roof plane. These dormers have a gable end and shed water off the roof’s surface instead of letting it run down into the wall’s foundation. Because these types of dormers are larger than most, they also cost more, typically around $18,750–$30,000.

A dormer is a great way to increase your home’s living space. It can also add another roof overhang for protection from rain, sun, and snow. A dormer looks especially appealing on Cape Cod, châteauesque, American foursquare, and neocolonial homes.

Dormer windows offer extra light, additional space, and plenty of ventilation. They also add aesthetic value that prospective buyers may love. In fact, installing a dormer can increase your home value by 20%.

On the other hand, dormers are expensive, challenging to install, and require consistent maintenance. If made cheaply, they can rot, warp, or gap around the flashing and may result in a power bill increase. To ensure your roof lasts a long time, roofing experts recommend annual inspections and roof maintenance checks. These visits should include replacing any damaged flashing and checking seals around windows, doors, chimneys, and vents to prevent leaks.

Regularly cleaning your gutters is another key part of dormer maintenance. When installing gutters, use downspouts and roof drip edges that direct water away from the house to prevent roof damage.

Many factors can impact dormer costs, from the type of dormer to the material used to construct it. Here are the major expenses. 

Labor Costs

Expect to spend about $35–$55 per hour, per employee to install a dormer. The actual cost of labor depends on several variables, such as your location and the contractor’s business model. Typically, fees run higher in urban areas than rural ones, and some contractors may charge a flat fee instead of an hourly rate. It’s typically more cost-effective to install a dormer when putting on a new roof than to add one to an existing roof. 

Permits and Inspections

Permits are needed to ensure the project meets current building codes. These range in price from $390–$1,930. Your municipality may also require a post-construction inspection, which you’ll pay for.

Roof Deck Replacement

When adding a dormer, you may need to remove the existing roof deck if it will interfere with insulation or ventilation. The average cost of removal is around $5–$8 per foot of roof deck, but expenses will vary depending on project size, shape, and location.

Roofing Material

The roofing material used on the dormer will impact the project cost. For example, a metal roof requires special installation and is more expensive, while cedar shingles are easier to install and less expensive. The material cost may also be impacted by whether an expert does the work.

We don’t recommend installing roofing yourself for several reasons—the most prevalent being that it’s dangerous. Professional roofers are experts and have experience in advanced home improvement projects. 

DIY Dormer Installation

Adding a dormer to your home is not a DIY project. You’ll need to hire a contractor for the job. The roof should undergo an inspection before construction begins. During the project, you’ll need temporary support structures while the dormer is being built. Then, the dormer will have to be framed, roofed, shingled, and inspected—all major tasks requiring specialized skill and knowledge.

Professional Dormer Installation

Installing a dormer requires intricate knowledge of carpentry as well as building codes and regulations that may vary regionally. A professional will understand these and other project intricacies, and can solve any problems that may arise along the way. Here’s how the process usually works:

1. You set up an initial consultation for the contractor to provide a quote. 
2. The contractor surveys your house to figure out square footage and what’s needed in terms of materials.
3. The contractor provides a detailed proposal and payment schedule or financing information.
4. You sign a contract with the roofing company you want, and they get started on your project. 

We recommend getting quotes from at least three contractors before making a final decision.

A dormer can add light, space, ventilation, and even value to your home. But adding a dormer to your roof is not an inexpensive, do-it-yourself project. It requires a professional’s skills and tools.

The cost of adding dormers depends on factors like your roof size, roof truss cost, and number of dormers. It also varies based on materials used and your location. Expect to spend up to $30,000 on materials and labor; call a local builder or contractor to get a more detailed quote.