How Much Does It Cost to Add a Dormer?

Typical Range:

$2,500 - $20,000

Find out how much your project will cost.

Cost data is based on research by HomeAdvisor.

Updated March 23, 2020

Written by HomeAdvisor.

Dormer Installation Costs

It typically costs between $2,500 to $20,000 for professional dormer installation, or about $115 per square foot. There are several options for dormers, including shed, flat, gable and hip. Smaller projects, like adding a window dormer, cost about $4,000. Larger remodels like adding a bathroom dormer run about $24,000.

Depending on the scope of the work – like adding multiple dormers – cost can climb over $100,000. Speak with a roofer near you about the specifics of your renovation to find out about the exact price.

Factors that impact dormer installation costs include:

  • Size and shape.

  • Permits.

  • Type of roof.

  • Interior work, like drywall, painting, other finishing work.

  • Local materials and labor costs.

Dormer Cost Calculator

Average Cost$12,000
High Cost$20,000
Low Cost$2,500

Average Cost to Add a Dormer by Roof Type

TypeCost Per Square Foot

Shed Dormer Costs vs. Gable Dormers

Gable dormers, also known as doghouse-style, are commonly found on roofs that have a steep pitch and have an angle. Gable dormers are an attractive and cost-effective add-on that can let more light into your home.

Shed dormers are a bigger investment with benefits like increased square footage. Some people find shed dormers are the best way to add headroom and space to smaller homes.

A combination of a shed and gable dormer is known as a Nantucket dormer. For this type of upgrade, roofing pros erect two gable dormers and connect them with a shed dormer.

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Cost of Building Dormer on an Existing Roof

Type of House or AdditionCost
Cape Cod$110-$150 per square foot
Bungalow$110-$150 per square foot
Attic$75-$120 per square foot
Bathroom$24,000 average each
Window$4,000 average each

Cost to Dormer a Cape Cod

You’ll usually pay between $110 and $150 per square foot to add dormers to a Cape Cod-style house. You’ll pay less if you opt for a hipped or shed, but most people prefer gable dormers for this type of home.

Cape Cod houses and bungalows are especially popular on the East Coast, and location can affect what you’ll pay to add a dormer. For example, dormer cost on Long Island is closer to $150 per square foot and up. Price is at the lower end in a less expensive area like Kansas City, Missouri.

Cost of Adding a Dormer to a Bungalow

Like a Cape Cod dormer, expect to pay between $110 and $150 per square foot to upgrade your bungalow. Usually, you’ll find gable dormers go with this type of architecture.

Attic Dormer Extension Cost

The best way to maximize space in your attic is to install a shed dormer which costs between $75 and $120 per square foot.

However, there are other dormers, including gable dormers that people sometimes prefer. That’s because they let in more light and improve ventilation.

Interested in a full attic conversion? The average national cost for attic renovations is about $50,000.

Dormer Bathroom Addition Cost

It typically costs about $24,000 to install a bathroom dormer. This number includes labor and material cost. It’s important to remember that those numbers can change based on where you live.

If you’re looking for a larger upgrade, the cost to remodel a bathroom with a dormer addition ranges from about $30,000 to $39,000. Compare that price to the cost to remodel or renovate a house, which usually runs between $18,500 an $76,000.

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Dormer Window Cost

It costs about $4,000 to install a dormer window. This price is pretty typical – the cost to install a window usually runs from about $3,000 to $8,500.

Dormer windows are a great update to your home if you’re looking for natural light and more ventilation. It’s especially beneficial in a converted attic space. A home addition company near you can help break down the specific cost and timeline.

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Dormer Conversion Cost Factors

There are several components that make up the price of this job, which typically costs about $11,250. For example, the cost to frame a house ranges from $1,500 to $6,000 Framing is essential for an addition like a dormer, though you won’t necessarily need everything that comes with an entirely new add-on.

Here’s a look what makes up the price of a dormer conversion:

DIY vs. Hiring a Construction Professional

If you think dormers are right for your home, it’s best to leave the job to professionals. They’ll help get local permits, follow building codes and address any structural concerns they may find with your home. It might seem expensive, but you’re going to open up your roof and put more weight on your home’s framing and foundation, which makes the cost worth it.

If the job isn’t done properly, you risk damaging the structural integrity of your house and needing expensive repairs as a result.

Faux & Prefab Dormer Costs

Prefabricated dormers cost between $8,000 and $14,000, labor and installation not included. The price comes from their size – usually, they tend to be larger – and the cost associated with building, transporting and lifting them.

You can purchase faux or “fake” dormers at home improvement outlets. It’s cheaper to go this route, but you won’t reap the benefits of increased square footage or ROI.

Prefab or faux dormers are more common with DIY projects, but it’s still a difficult roof project that only experienced DIYers should take on.

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Do dormers add value to a house?

Yes, dormers add value to a house. The return on investment (ROI) for this project is only about 40%, but with the added light that comes into your house, you can save money on electricity bills over the years. This may offset some of the low ROI.

You can raise the value of your home with other remodeling projects like adding a deck, finishing your basement and upgrading your kitchen.

How much square footage does a dormer add?

Typical dormers typically add about 250 square feet, but this can be higher depending on the type of you have installed, if you’ve remodeled other parts of your home, or if you’d built on an addition.

How much does dormer cladding cost?

Dormer cladding can cost anywhere from about $2 to $15 per square foot. Prices vary based on local material and labor costs, so the actual price may be much higher. Cost factors include:

  • Type of cladding.

  • Material removal.

  • Size of coverage area.

How long does it take to build a dormer?

It takes anywhere from 4 weeks to 6 months and beyond to build a dormer. The total timeline depends on factors unique to your project, like:

  • Its style.

  • Permits needed.

  • Its size.

  • Roof work.

  • Necessary foundation work.

  • Interior finishing.

Is your pro recommending extra upgrades to your roof? On average, to replace or install a roof costs between $5,350 and $10,650. During major rebuilds or remodels, you may opt for a different roof frame, like roof trusses.

Roof trusses cost between $7,200 and $12,000, depending on labor and material cost in your area.

What is a full dormer?

A full dormer is also known as a shed dormer. It’s one of the most basic types of conversions you can make. Dormers and dormer windows are popular add-ons during remodels like attic or loft conversions. They’re also installed to improve the curb appeal and look of a home. Generally speaking, people use the word “dormer” to refer to three separate components of a remodel:

  • A converted room on the second or third floor.

  • A horizontal extension of a room.

  • A window in the extended room.

Usually, you put dormers on sloping roofs. You can choose a flat, arched, hipped, pointed or ornamented roof for your dormer. Dormers are also sometimes flush with the wall of the first floor.

Do you need planning permission or a permit for a dormer?

You might need planning permission or a permit for a dormer; generally, a building permit costs about $1,160, or between $390 and $1,930. This truly depends on local laws. Check with a local planning authority who can help answer that question more directly.

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