How Much Does It Cost to Add a Dormer? [2025 Data]

Cost to Add a Dormer by Square Feet

The cost of adding a dormer increases with size. Most dormers cost between $80 and $200 per square foot. An average dormer is around 100 square feet, though they often range from 25 to 250 square feet. 

Here are the average costs for different-sized dormers.

Dormer Addition Cost by Material

As is the case with any building project, the cost of your new dormer depends on the quality of the materials you choose for the roofing, windows, and siding. In many cases, homeowners choose materials that match others on their home’s exterior, especially when it comes to roofing.

Asphalt roofing is one of the most popular choices and is wallet-friendly. If you’re looking for longevity, a metal roof can last twice as long. Metal costs 30% to 50% more than an asphalt shingle roof, but you’ll save on replacement costs down the road. Consult a roofing company near you to help you get the right materials at a reasonable price.

Cost to Install a Dormer by Style

The style of dormer you choose isn’t just a matter of aesthetics—there are unique benefits to each dormer style that suit different homes. More architecturally complex styles, such as a gable dormer, have higher costs, while something that requires less on-site labor, like a prefab dormer, is more budget-friendly.  

Here’s a look at popular dormer styles and their costs.

General Contractor Cost

While it might be tempting to cut costs by doing the project yourself, this project is best left in a professional’s hands. Labor costs account for around 50% of the overall budget, or about $8,000 on average. 

Your general contractor may bring in a team of experts to collaborate on the job. For example, they may hire a structural engineer to sign off on the stability of your roof. A roofer and window installation contractor will then collaborate, possibly bringing in a siding specialist as well. Per-hour rates will range depending on each specialist's level of expertise.

The most common tasks involved in installing a dormer and their average costs are:

• Design and permitting: $1,000 – $2,000

• Constructing the frame: $2,000 – $5,000

• Adding flashing and shingles: $1,500 – $3,500

• Installing windows: $500 – $1,500 per window

• Installing wiring and lights: $500 – $1,500

Additional Dormer Cost Factors

Labor and materials account for most of the cost of installing a dormer, but there are a few other cost factors that contribute to what you’ll pay in total. 

Roof Removal

To make space for the new dormer, your contractor will need to remove each layer of your roof in that area. The sheathing, underlayment, and flashing will all need to come up, and in some cases, you'll need to alter the roof framing to make way. Depending on the size of your dormer, making these changes to the structural components of your roof might necessitate a structural engineer, which can increase your costs.

Budget between $5 and $8 per square foot to remove the roofing materials.

Roof Repairs

The cost of roof repairs ranges between $350 and $1,200 per square of roofing material, but issues can really run the gamut. Your contractor may discover water damage, missing shingles, or the need for updated insulation or even structural elements. It’s crucial to address these repairs beforehand so the dormer construction goes smoothly and to prevent future problems. 

Foundation Reinforcement

Adding a dormer might require reinforcing your home’s foundation to support the additional weight. The cost of foundation reinforcement can rack up your expenses significantly, ranging from $4,000 to $12,000. 

Cladding

Since dormer additions are more prone to the elements—particularly water damage—contractors will often choose cladding over traditional siding. Cladding sits on top of a layer of insulation or a vapor barrier to add extra protection to the interior walls. Cladding costs between $2 and $15 per square foot. 

Permits

Before undertaking a significant construction project like adding a dormer, you need to pay fees to your local building department for permits. Building permit costs can vary based on your location and the project's complexity, but you can expect to pay between $400 and $2,000 for most projects. Getting the proper permits ensures that you avoid potential fines.

Cleanup

Once construction is complete, professional cleanup services might be needed to remove debris and scraps. Post-construction cleanup costs around $300 to $800. 

DIY vs. Hiring a Pro to Build a Dormer

Building a dormer yourself can save on labor costs, which account for $3,000 to $13,000 of the total cost. You could potentially save up to 50% of the initial cost, but it’s important to understand the significant risks involved in tackling a dormer addition on your own.

While the savings may be enticing, building a dormer is a complex project that’s best left to the pros. It’s important that the dormer is structurally sound and properly integrated with your existing roof, which professionals have the tools and expertise to ensure. Plus, working on a roof is dangerous, especially for those without prior experience. 

Not to mention, you might spend more in the long run if you need to hire a professional to fix mistakes. Instead of taking on this challenging project yourself, consult with a general contractor near you to ensure the safety and quality of your home.  

How to Save Money on Dormer Addition Costs

Adding a dormer is a major investment, but there are several ways to manage and reduce costs without compromising on quality. 

• Opt for a Simpler Design: Complex dormer designs can increase labor and material costs. Something simpler, like a shed dormer, is functional while being more gentle on your budget.

• Use Standard-Sized Windows: Custom windows can be costly, so sticking with standard-sized windows that fit your dormer designs can lower the cost of window installation.

• Shop for Materials Yourself: While contractors can purchase materials on your behalf, you could find better deals by shopping around yourself.

• Consider a Prefab Dormer: Prefab dormers are built off-site and can be installed quickly, reducing labor costs.

• DIY Finishing and Painting: If you have the skills, consider handling interior finishing and painting yourself. This can reduce labor costs and give your dormer a personal touch. 

Do Dormers Increase Your Home Value?

A new dormer not only enhances your home’s aesthetic appeal but can also increase its market value. On average, the ROI for adding a dormer is 40% to 50%. This means that if you spend $10,000 on a dormer, you could increase your home’s value by $4,000 to $5,000. 

Dormers appeal to potential buyers in a few ways:

• Adding living space to your home

• Including windows that bring in more natural light

• Enhancing curb appeal

• Improving ventilation, especially in upper floors or attic spaces

All of these factors contribute to making your property more desirable and valuable, making the long-term benefits and ROI of a dormer worth weighing against its cost.

How Angi Gets Its Cost Data

Home is the most important place on earth, which is why Angi has helped more than 150 million homeowners transform their houses into homes they adore. To help homeowners with their next project, Angi provides readers with the most accurate cost data and upholds strict editorial standards. We extensively research project costs to develop the pricing data you see, so you can make the best decisions for you and your home. We rely on reputable sources, including the U.S. Bureau of Labor Statistics, academic journals, market studies, and interviews with industry experts—all to ensure our prices reflect real-world projects. 

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