How Much Does Adding a Dormer Cost?

Dormers are a great way to increase space and light in the attic of a home. However, the cost to add them to an existing roof can require major reconstruction and turn a seemingly small, simple home addition into a project that runs into the tens of thousands of dollars.

In this article, I’ll discuss the cost of dormers and their various types and give you some insight I’ve gained from building them professionally.

If you’re looking for a new roof (including dormers), get a quote today from one of my recommended roofing contractors:

What Is the Cost of a Dormer?

All costs in this article assume that adding a dormer means only framing and exterior work. We treat interior work, if there is any, as a separate cost.

I do this because you can add a dormer to a non-habitable attic space, in which case you need no interior finish work. However, you can also add a dormer to a finished attic space. In those cases, dormers need finish work. For our examples here, I’ve chosen to only address the exterior work.

Here’s a table for the basic cost range for adding a dormer:

For a brief look at dormers, check out this video to learn about their benefits and why you might choose to add one to your home:

Dormers are difficult to cost out because each home is different, and the work needed to accommodate a dormer is variable. I’ve done some that required little frame restructuring and some that required a lot, and there’s no easy way to quantify the reasons for those differences in the chart.

This chart is generalized and assumes a typical case for a home built within the last 40 years and in a common style. Homeowners with older homes, unique or uncommon designs, should be aware that costs could — and likely will — fall outside these ranges. In general, you can expect to pay $40 – $120 per square foot.

Gable

Hip

Gable dormers range in cost from $5,000 to $12,000. They’re common in residential homes. Sometimes called doghouse dormers, they’re an easy, cost-effective dormer that blends seamlessly into the house. You can also combine them into a Nantucket dormer.

These can either be functional or aesthetic. Gables make a nice little nook for a chair or reading spot in a finished attic. In an unfinished attic, they enhance the house’s overall appeal by adding visual interest to its architecture.

Like gable dormers, hip roof dormers cost between $5,000 and $12,000. are framed with a hip roof but are the same as gable dormers. In terms of cose, they’re almost identical. In most cases, it’s not worth it for most contractors to expend effort to figure out what is. In the end, there’s minimal difference in material or labor.

Shed

Shed dormers have the widest cost range of all dormers between $4,000 and $40,000. Design is a key element in the cost. Shed dormers are flat roof dormers extending from the main roof pitch, though they sometimes have a sloped roof. The unique aspect of a shed dormer is that it can be as wide as the homeowner wants. Because of that, it can blur the line between a dormer and a pseudo-clerestory or attic extension.

Because canvas are simple to construct, they’re great options for homeowners to turn an attic into extra living space. Their boxy design means they’re perfect for adding extra space and headroom to the attic because they eliminate some of the ceiling slope and create a more conventional square space.

Eyebrow

The price of eyebrow dormers lands between $6,000 and $15,000. This style of dormer was common in historic European architecture, but they’ve seen some use in America. They’re a unique type of dormer with an unmistakable look, but there are some factors to consider. Eyebrow dormers don’t usually create as much interior space as other dormer styles, so they might not be the best choice for homeowners looking to maximize the liveable space in their attic. They’re also more complicated to construct, so you can expect to pay more.

I think they’re best suited for homeowners looking to add visual interest to their home and those looking to increase the natural light and ventilation in the attic. (Remember that you can open most dormer windows to allow air to circulate in the attic and reduce heat build-up during warm months.)

Arched

Arched dormers have a classic and high-end design that’s widely employed in architectural styles like French Neoclassical, and they cost from $7,000 to $20,000. Designers often pair them with other elements, like faux pediments, for a stately, palatial look.Arched dormers have a classic and high-end design that’s widely employed in architectural styles like French Neoclassical, and they cost from $7,000 to $20,000. Designers often pair them with other elements, like faux pediments, for a stately, palatial look.

Because of that, arched dormers are one of the more expensive dormers. While the dormer’s material and labor costs aren’t substantially different from other styles, most homeowners want to adorn those arched dormers and highlight them as an architectural accent

Which Factors That Impact How Much Adding a Dormer Costs?

Like any construction project, a variety of factors influence cost, from size to materials to internal construction needs. Unlike most construction projects, dormers are fairly rigid in their price, and there aren’t many money-saving options to choose from. A homeowner can save money in interior finish work (if there is any).

Square Footage

The square foot of the dormer determines how much of the roof deck a builder must remove and how much reframing and potential reinforcement the builder must do. It also roughly correlates to how many shingles will be required to cover the dormer. Naturally, that means larger dormers are more expensive than smaller ones.

Interior Reconstruction and Reinforcement

Roofs that weren’t constructed with dormers initially often need somewhat involved reframing to accommodate them. This reframing is sometimes more than the roof deck and rafters and extends into the roof’s interior framing.

The worst-case scenario for reconstruction requires reframing trusses. In a project like that, a structural engineer is necessary. They’ll have to come in beforehand to assess whether adding a dormer addition is possible and what kind of reconstruction will be required. They’ll also have to inspect the work as it’s going on or when it’s finished to ensure it meets engineering standards.

Material Costs

As we’ve seen, the market for construction materials isn’t immune to economic factors. The price of common construction materials rose precipitously in 2021-22, and that cost was passed on to clients.

Thankfully, prices have come down somewhat since then. Still, it’s good to remember that construction is susceptible to inflation, so in those periods of economic inflation, maybe hold off until things settle down.

Roof Pitch and Complexity

Certain roof types, especially steeped-pitched roofs, are difficult to work on, which means more labor is involved to get things done and get them done safely. As such, dormers on a steep pitch will cost more than dormers on a walkable pitch.

Similar to that, the complexity of the roof — or the potential complexity of the dormer’s location — can cause higher average costs. Complexity adds difficulty, which takes more time to contend with, which drives up the labor inputs. There is also the cost of skill, as a highly-skilled professional capable of tackling a complex project will charge more than a lower-skilled professional.

Multiple Dormers

Having multiple dormers is a cost factor, but it’s different from the others. Multiple dormers cost less per dormer than a single new dormer because contractors are already on site. We have our equipment, we’ve scheduled our workers, and we already have an account with the material supplier. It costs us less to do a second, third or fourth dormer because all the organization, sales, purchasing, and paperwork is already done.

If you intend to install multiple dormers on each side of the house, it may seem more economical to do one side this year and the other next year. But in the end, it’ll be cheaper to hold off, save the money, and get them all done in one go.

Permits

Dormers, because they require roof reconstruction, usually require a building permit. In some jurisdictions, they’ll also require inspection. Regrettably, this can slow down the project, but they’re necessary. Building codes save lives, and permits are one of the mechanisms used to ensure that local authorities have adequate funds to hire inspectors to enforce proper building techniques and keep occupants safe.

Location

Construction workers have to make a living, too. If you live in an area with a high cost of living, your local contractors also live in an area with a high cost of living. Because of that, they have to charge accordingly, so you can expect to pay as much as 15 – 30% more in those areas over the national average.

What Are the Benefits of Investing in a Dormer?

Dormers fall into the personal benefits category. Because of how involved they are in building, I wouldn’t expect a very good return on investment from them, even if it increases curb appeal. Again, that’s not to say they’re not worth it, but a homeowner should be aware that — financially — they’re often a loss.

Professional Vs. DIY Dormer Cost

Dormers are a professional project. Because of the major reconstruction involved, errors and failures can be costly and jeopardize the roof’s integrity. I can’t stop you from doing a dormer yourself, but you should be knowledgeable and confident that you know what you’re doing.

Adding a Dormer Yourself

If you’re determined to do it yourself, I would strongly advise recruiting a knowledgeable person to help you. Even if you know what you’re doing, I strongly recommend recruiting an experienced person to help you. Even as a professional, I rely on other professionals to check my work and make sure I haven’t overlooked something.

Hiring a Professional To Add a Dormer

Hiring someone to add a dormer is as straightforward as hiring for other projects. Even though the process is more involved and often requires engineers and inspections, the contractors should be able to organize that for you or guide you.

1. Find local experts near you: Despite involving the roof, adding a dormer is more within the trade of carpenters than roofers. As such, I would look for general contractors and residential construction companies first.
2. Get a quote from a few options: As with all major work on a house, shop around to ensure you get a fair price. Check the internet for average rates for the type of work you’re considering.
3. Consult them about their recommendations: The contractor will explain any variables or potential issues. If you have any questions or concerns, be sure to tell them. They’ll be happy to answer them.

So, Is Adding a Dormer Worth the Cost?

It’s worth it only if it’s for personal home improvement. Adding dormers often costs more than any monetary value it adds to the house. So, homeowners should be aware of that.

But don’t let that discourage you. If you’re in your forever home, dormers can turn drab or unused attic space into a bright, unique space for a guest room, child’s room, office, or general recreation.