How Much Does It Cost to Add a Dormer?

Margaret Wack
Written by Margaret Wack
Updated May 25, 2021
three dormer windows with blue sky in background
Photo: Marje / E+ / Getty Images

The typical cost to add a dormer is $2,500 to $20,000, with an average cost of $12,000

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Dormers are a great way to increase space in smaller homes and make even the tightest spaces bright, airy, and welcoming. If you have a cramped attic bedroom or playroom, a dormer can help you maximize the potential of the space. Dormers can also add some flair to your upper story. The cost of dormers depends on various factors, including the size of the project, your roof type, and any necessary permits.

How Much Does It Cost to Add a Dormer Per Square Foot?

It costs an average of $115 per square foot to add a dormer. Popular options include shed, flat, gable, and hip dormers. The overall cost of adding a dormer also depends on your roof type and where you plan to install the dormer. For example, a bigger project like adding a bathroom dormer costs about $24,000.

How Much Does It Cost to Add a Dormer Near You?

The price of adding a dormer costs an average of $12,000 nationwide. This price doesn’t vary much by location. However, some areas do require additional building permits before you can install a dormer. Building permits typically cost an extra $390 to $1,930.

How Much Does It Cost to Add a Dormer Yourself?

No matter how handy you are, installing a dormer probably isn’t a project that you can complete for yourself. Improperly adding a dormer can result in structural damage to your home. For this reason, leave dormer additions to the professionals.

Professionals will install the dormer properly and make sure that your home can bear the additional weight. They will also acquire any necessary permits. If you’re interested in adding a dormer, you should contact a home remodeling professional near you to get started.

Dormer Cost Breakdown

There are a variety of factors that influence dormer costs. These include the size of the project, your roof type, permits, and labor costs.

Project Size

The cost of adding dormers can vary widely depending on the size of your project. For example, larger projects like installing multiple dormers on your house can cost upwards of $100,000 in some cases.

Roof Type

Dormer costs also vary by roof type. For example, adding a flat dormer costs an average of $80 to $125 per square foot. In contrast, adding a gable dormer costs an average of $110 to $150 per square foot.

Required Permits

Not all locations require a building permit to add a dormer to a residence. If your location does require a permit, the cost can range from $390 to $1,930.


Labor is another factor when it comes to the cost of adding a dormer. While it might be tempting to cut costs by doing the project yourself, this is one project that’s best left in the hands of a professional. Labor costs can range between $30 and $50 per hour, with many contractors charging a flat rate depending on the project.

How Much Does Adding a Dormer Cost by Type?

orange dutch-style dormers
Photo: Richard Sharrocks / Moment / Getty Images

Costs vary depending on your house type and installation location.

Dormer TypeCost
Cape Cod$110 – $150 per sq. ft.
Bungalow$110 – $150 per sq. ft.
Attic$75 – $120 per sq. ft.
Window$3,000 – $8,500

Cape Cod

It typically costs between $110 to $150 per square foot to install a dormer on a Cape Cod-style home. If you’re the proud owner of this charming type of home, a dormer can help accentuate its best features. A dormer can also provide additional liveable space in a smaller home.


You can expect to pay around $110 to $150 per square foot to add a dormer to a bungalow. Gable dormers are a popular option for single story bungalow-style homes, which often have unfinished or under-utilized attic space.


Installing a dormer in an attic costs between $75 and $120 per square foot. If you have a cramped attic, a dormer is a fantastic way to pep up the space and make it more livable. Attic dormers can let more natural light in and help convert a small third story into the perfect spare bedroom or playroom.


A bathroom dormer costs an average of $24,000. This type of dormer is more expensive because it usually requires a more extensive remodel. Bathroom dormers can brighten up a space and make it a perfect setting for bubble baths, spa treatments, and more.


It costs about $3,000 to $8,500 to install a window dormer. Window dormers are an affordable option, allowing you to reap the many benefits of dormers at a lower price point. While window dormers don’t afford any extra square footage, they can help transform a dark, cramped space into a cheery, light-filled room.

How Much Does It Cost to Add a Dormer by Style?

Wondering just how much your dream dormer addition may cost you? Here are some common types of dormers, along with how much you can expect to pay to have them installed:

Dormer StyleCost
Shed Dormer$75 – $120 per sq. ft.
Gable Dormer$110 – $150 per sq. ft.
Nantucket Dormer$95 – $140 per sq. ft.
Flat Dormer$80 – $125 per sq. ft.
Hip Dormer$115 – $135 per sq. ft.
Prefab Dormer$8,000 – $14,000

Shed Dormer Cost

Shed dormers cost an average of $75 to $120 per square foot. This type of dormer is an excellent option if you’re looking to add square footage to a room and increase space in a small home.

Gable Dormer Cost

You can expect to pay between $110 and $150 per square foot for a gable dormer. Gable dormers are a popular choice for roofs with steep eaves. They’re also great for brightening up dark rooms and making a space feel lighter and more open.

Nantucket Dormer Cost

Nantucket dormers cost between $95 to $140 per square foot to install. If you can’t decide what dormer is right for you, a Nantucket dormer is the perfect compromise. This type of dormer consists of two gable dormers linked by a shed dormer.

Flat Dormer Cost

Flat dormers cost an average of $80 to $125 per square foot. As the name suggests, these dormers have a flat roof, which gives them a boxy appearance. Flat dormers can be a perfect way to expand a tight room and provide more space. Just be careful if you live in an area with lots of snow—leaks are more likely with this design than with a sloped roof dormer.

Hip Dormer Cost

You can expect to pay an average of $115 to $135 per square foot for a hip dormer. Hip dormers are another attractive option if you’re looking to transform a smaller space and let in more light. Hip dormers feature roofing on three sides.

Prefab Dormer Cost

Prefab dormers cost between $8,000 and $14,000 for the materials alone, not including labor and installation. These dormers are typically larger than other types, which can further increase square footage, but comes with an additional cost.


What should I consider when adding a dormer?

If you’re thinking about adding a dormer, you should find out which type will help you achieve your home goals For example, if you’re trying to expand a small space, you might want to go with a shed dormer. If you’re just trying to let in a little light, you might want to stick with a more affordable window dormer.

What other projects should I do at the same time?

Remodeling often goes hand in hand with installing a dormer. Adding a dormer often already requires significant construction, making it an ideal complement to a more extensive renovation of an attic or second floor.

Do dormers increase your home’s value?

Dormers are a great way to increase the value of your home and add curb appeal. In most cases, dormers have an ROI of about 40%. To further raise the value of your home, you might consider converting your attic or creating an accessible loft.

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