Dormers cost an average of $24,000 to install, with prices ranging from $18,750–$40,000, depending on the style you want. Dormers add natural light, increase interior space, and boost your home’s interior and exterior curb appeal. Our guide covers the costs of adding a dormer so you can plan your project with confidence. You’ll also learn insights from several experts featured in This Old House’s magazine, including general contractor Tom Silva.
Key Takeaways
- Adding a dormer costs around $24,000 on average, with costs varying by style from $18,750 for shed dormers to $40,000 for eyebrow dormers.
- Labor costs range from $35–$55 per hour per employee, with permits and inspections adding $390–$1,930 to the total project cost.
- Shed and flat roof dormers are the most affordable options at $75–$125 per square foot, while eyebrow dormers are the most expensive at $105–$160 per square foot.
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What Is a Roof Dormer?
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, chateau-esque, American foursquare, and second empire.
Pro Tip
- If your home has a low-slung roof, it can benefit from a large dormer that exceeds the height of the primary roof and extends toward the front of the house, according to This Old House’s magazine. Adding a few feet of dormer depth to the end of a hallway creates room for a desk while also letting in natural light.
How Much Do Different Dormers Cost?
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.
You may have additional installation costs to consider, depending on the dormer style you choose, according to Tom Silva. “Anytime you build something that breaks away from a straight line, it costs more,” Silva adds. For example, curved or eyebrow dormers require custom sashes and framing, all of which increase project costs.
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 and can cost $25,000–$37,500, depending on the construction material used.
Eyebrow or 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.
Read More: Adding an Eyebrow Window
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.
You can quickly compare the cost of different styles of dormers using the chart below.
| Dormer Style | Cost per Square Foot | Average Total Cost |
|---|---|---|
| Arched top | $100–$150 | $25,000–$37,500 |
| Eyebrow or eyelid | $105–$160 | $26,250–$40,000 |
| Flat roof | $80–$125 | $20,000–$31,250 |
| Gable | $110–$150 | $27,500–$37,500 |
| Hipped | $115–$135 | $28,750–$33,750 |
| Shed | $75–$120 | $18,750–$30,000 |
Note: The cost data featured in this guide is based on estimates from Angi and HomeAdvisor, unless otherwise noted.
Pros and Cons of Adding a Dormer
Pros
- Added curb appeal
- Increase your home’s living space
- Offer extra light, additional space, and ventilation
Cons
- Expensive and challenging to install
- Requires maintenance
- If made cheaply, they can rot and warp
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, increasing your home’s valuation.
On the other hand, dormers are expensive and challenging to install. If made cheaply, they can rot, warp, or gap around the flashing. To ensure that your roof lasts a long time, experts recommend annual inspections and roof maintenance checks that also involve dormers. These visits should include replacing any damaged flashing and checking seals around windows, doors, chimneys, and vents to prevent leaks.
If your dormer has gutters, regularly cleaning them is another key part of maintenance. When you install gutters, use downspouts and roof drip edges that direct water away from the house to prevent roof damage.
Pro Tip
- Poorly designed dormers can actually hurt your home’s curb appeal and functionality, according to an architect featured in This Old House’s magazine. Finding a designer who has experience with adding dormers to a residential roof can help ensure the job is done right.
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Other Factors That Impact Dormer Costs
Many factors can impact dormer costs, from the type of dormer to the material used to construct it. Learn more about the major expenses in the dropdown sections below.
Labor
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
Your project will require the work of an engineer who can create a dormer design that fits with your home’s structure. Permits will then be needed to ensure that the project meets current building codes. These range in price from $390–$1,930. Your municipality may also require mid- and post-construction inspections, which you’ll pay for.
Roof Deck Replacement
When adding a dormer, you’ll almost always need to remove the existing roof deck. 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 is more expensive and requires special installation, while asphalt shingles are easier to install and less expensive. You’ll also have to factor in the old roofing material and how expensive it is to take off. The material cost may also be impacted by whether an expert does the work.
Can You Install a Dormer Yourself?
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 do-it-yourself (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:
- The contractor provides a detailed proposal and payment schedule or financing information.
- The contractor surveys your house to figure out square footage and what’s needed in terms of materials.
- The contractor provides a detailed proposal and payment schedule or financing information.
- 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.
Is Adding a Dormer Worth It?
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 the 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.
Pro Tip
- Adding a dormer is easier and offers better functionality on steeper-pitched roofs than on lower-pitched roofs. Lower-pitched roofs requires dormers to extend further inside the home, which reduces the amount of natural light that can enter.
FAQs About Dormer Costs
How much space does a dormer add?
A new dormer can add up to 250 square feet of space to your house. This will depend on the dormer style and your home’s construction.
How long does it take to add a dormer?
Building a dormer may take four weeks to six months to complete. It’s a long and complex task, but the end result is often worth it.
Do dormers add value to a house?
A new dormer offers an excellent return on investment and can increase your home value. You’ll also get to enjoy the extra light and living space a dormer provides while living in the home.
Do I need an architect to add a dormer?
You may not need an architect to add a new dormer, but you’ll likely need a building permit. A building permit for a dormer usually costs $390–$1,930, with a national average of $1,160.
How We Determined Dormer Installation Costs
To provide accurate and current pricing for dormer installation projects, we collected project estimates from Angi and HomeAdvisor. This allows for cost averages that reflect the diverse needs of homeowners across both local and nationwide markets. The pricing shared in this guide represents cost ranges and averages based on our research at the time of publication. Actual costs may vary depending on factors such as your location, chosen contractor, dormer type, and overall project scope.
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