How Much Does Adding a Dormer Cost?

Installing dormers can dramatically boost the usable space and natural light in your attic — and add major curb appeal in the process. But they’re not cheap. Depending on the type, size, and your existing roof structure, adding a dormer typically costs between $12,000 and $30,000, with complex, full-sized dormers pushing that number even higher.

The biggest cost drivers are the extent of roof reconstruction required and the finish level inside the dormer. A simple shed dormer added to a modest home might cost $10,000–$15,000. But if you’re cutting into a steep-pitched roof or building multiple dormers with added insulation, drywall, and electrical, costs can easily double or triple.

In this guide, I’ll walk you through dormer types, pricing factors, and real-world advice from years of hands-on experience building them. If you’re also considering a roof replacement while you’re at it, it often makes sense to combine the projects — and I’ll explain why.

What Is the Cost of a Dormer?

Adding a dormer typically costs between $12,000 and $30,000, depending on the size, style, and complexity of the roof. That price covers just the structural and exterior work — framing, roofing, windows, and siding. If you’re converting the attic into a living space, expect another $5,000 to $15,000 for insulation, drywall, electrical, and finish work.

Some homeowners add dormers purely for natural light and ventilation in an unfinished attic, while others use them to create full bedrooms or bathrooms. Because of that wide range, we’ve separated out the base costs from interior upgrades.

Here’s a simplified cost range for exterior dormer construction:

💡 Tip: Combining dormer construction with a full roof replacement can save on labor and staging costs.

Dormer prices vary by style — not just because of the look, but because some designs require more framing, flashing, or finish work. Here’s what you can expect based on the dormer type:

Gable Dormers

Hip Dormers

Gable dormers (aka doghouse dormers) are among the most popular types for their clean look and lower cost. They’re ideal for adding a reading nook or extra headroom and natural light to finished or unfinished attic spaces. You can also combine several into a Nantucket-style dormer for added symmetry.

Gable dormers (aka doghouse dormers) are among the most popular types for their clean look and lower cost. They’re ideal for adding a reading nook or extra headroom and natural light to finished or unfinished attic spaces. You can also combine several into a Nantucket-style dormer for added symmetry.

Hip dormers look similar to gables but have a hip-style roof with three sloped sides. Structurally and cost-wise, they’re nearly identical to gables, though they take slightly more skill to frame and flash properly.

Shed Dormers

Shed dormers are the most versatile and most expensive option — but they add the most space. These flat or gently sloped roof dormers can run the entire length of the house, turning cramped attic space into usable square footage. They’re ideal for full bathrooms, bedrooms, or home offices. Because of the size and design flexibility, costs can start at $10,000 and climb past $40,000 if you’re essentially adding a new room.

Eyebrow Dormers

Eyebrow dormers are all about looks. Their gentle arch creates a distinctive curved profile, perfect for classic or historic homes. But don’t expect a ton of added floor space — they’re better for adding light and architectural interest than functionality.

Arched Dormers

Arched dormers are similar to eyebrow styles but taller and often more ornate. You’ll find them on French or European-inspired homes, usually as part of a more decorative roofline. The labor and detail work involved makes them one of the pricier options.

What Factors Impact the Cost of Adding a Dormer?

Several factors influence the cost of dormer construction, and unlike many home projects, dormers don’t have a lot of budget options. You’re cutting into your roof — that’s major reconstruction — so you’re mostly paying for skilled labor, structural work, and careful planning. Here’s what impacts the final price:

Dormer Size (Square Footage)

The larger the dormer, the more framing, roofing, and materials are required. A wider dormer also means more structural reinforcement and sheathing — plus more roofing shingles or siding to tie everything in. A small dormer might cost $7,000, while a full-width shed dormer can easily exceed $30,000.

Interior Work (If Any)

If you’re finishing the attic space behind the dormer — adding insulation, drywall, electrical, or plumbing — that can add $5,000 to $15,000 to the project. Turning a dormer into a full bathroom? Add another $10,000+ for plumbing and tile work.

Structural Reinforcement

Older homes or truss-framed roofs may require serious modifications to support a dormer. This could include reframing the roof structure, reinforcing rafters, or rebuilding load paths. If trusses are involved, you’ll need a licensed structural engineer to design and inspect the modifications, which can add $1,000 to $3,000 or more to the job.

Material Costs

Roofing shingles, framing lumber, windows, and flashing prices can fluctuate based on market conditions. While material prices have come down since the 2021–2022 spike, they’re still volatile. It’s wise to build in a 10%–15% cushion in your budget for pricing changes.

Roof Pitch and Complexity

A steep or complex roof — or one with lots of intersecting planes — requires more scaffolding, more labor, and more time. Walkable roofs are easier and cheaper to work on. Dormers on steep-pitched or awkward areas of the roof will always cost more.

Multiple Dormers

There’s a volume discount when building multiple dormers at once. If you’re adding two or more, doing them together is almost always cheaper than spacing them out. Once a crew is set up and the project is permitted, the extra labor and material costs are incremental — not double.

Permits and Inspections

Because you’re altering the roof structure, dormers almost always require permits — and possibly structural inspections. Permits vary by location but usually range from $300 to $1,000. Don’t skip this step. It ensures the work is done to code and protects you during resale or insurance claims.

Your Location

Labor rates and material prices vary widely. In areas with a high cost of living, expect to pay 15%–30% more than the national average. Local permit fees, availability of skilled trades, and regional building codes can also influence the final cost.

What Are the Benefits of Adding a Dormer?

Dormers don’t usually offer a strong financial return — but they can be worth every penny if you’re planning to stay in your home long-term. The value here is in comfort, space, and style, not resale.

Here’s why homeowners choose to add dormers:

1. More Usable Space

Dormers turn awkward attic nooks into functional rooms. By adding headroom and eliminating some of the roof slope, they can transform an attic into a full bedroom, office, or bathroom. For homeowners with growing families or remote work needs, this can be a game-changer.

2. Natural Light and Ventilation

Even a small dormer adds a window — which brings in natural light, makes the space feel bigger, and improves airflow. This helps cut down on attic heat buildup and makes upstairs areas more comfortable year-round.

3. Curb Appeal

A well-designed dormer can completely change how your house looks from the street. It adds architectural interest, breaks up a flat roofline, and gives the home a more finished or traditional appearance. This boost in curb appeal may not show up directly in appraised value, but it makes a strong impression on future buyers.

4. Customization

Dormers are flexible by design. You can go small and simple with a single gable dormer for light, or go big with a shed dormer that opens up an entire floor. You can even blend styles or add decorative touches like arched windows or copper roofing to match your home’s aesthetic.

Just remember: Dormers aren’t about flipping your house — they’re about making your home better while you live in it.

Professional Vs. DIY Dormer Cost

Adding a dormer is not a beginner DIY job. You’re cutting into your roof — the very thing that keeps your home dry and structurally sound. One misstep can lead to leaks, framing failures, or worse. While it’s technically possible to build a dormer yourself, it’s rarely a good idea unless you have serious construction experience.

DIY Dormer Construction

If you’re a seasoned builder or tradesperson, you might be able to tackle a small dormer with help from a structural engineer. But even then, it’s not a solo job. You’ll need someone to double-check your work, handle safety protocols, and spot things you might miss.

You’ll also be responsible for pulling permits, making sure the work meets local codes, scheduling inspections, managing material deliveries and waste and ensuring your roof stays watertight during construction.

Bottom line: Even pros don’t do this alone.

Hiring a Professional

For everyone else, this is a job for a licensed contractor — ideally one with experience in structural framing, roofing, and residential remodeling. Good contractors can coordinate engineers, permits, and inspections. They’ll handle weatherproofing and flashing details, making sure your new dormer doesn’t leak. They can keep the project on schedule and up to code and ensure proper load-bearing structure

Expect to pay a premium for that skill — but it’s worth it. A poorly built dormer can lead to long-term water damage, insulation failures, or structural sagging.

Who to call: While roofers might assist with flashing and shingles, carpenters or general contractors are the pros you want for full dormer construction. Look for companies with residential remodeling experience, and always ask for photos of past dormer projects.

So, Is Adding a Dormer Worth the Cost?

Dormers are absolutely worth it — but only if you’re doing it for you, not for resale value. The cost of adding a dormer almost always outweighs the immediate boost in market value. But if you’re in your forever home and want to reclaim wasted attic space, add natural light, or improve your home’s layout, a dormer can be one of the most transformative upgrades you can make.

Think of it like this: You’re not just cutting into the roof — you’re carving out space for something meaningful. Whether it’s a bedroom for your growing family, a quiet home office, or a bright new bathroom, dormers let you reshape your home to better fit your life.

Just be prepared: this is a major structural project. It takes planning, permits, and professional skill. But done right, it can make your home feel bigger, brighter, and better — every single day you live in it.