What a Dormer Is and 9 Types to Consider

Does your home have an unused attic or maybe an upstairs room that is too small or too dark? Adding a dormer could turn these underutilized spaces into integral parts of your home. Dormers add both versatility and value to your existing residence. Use this guide to decide if a dormer addition would be the right project for you.

What Is a Dormer?

A dormer is a structure that projects out from the plane of a sloped roof, often including a window. The dormer structure has its own roof, siding, and sometimes even gutters that tie into the existing elements of your home. Some consider dormers the “eyes” of a house.

The word “dormer” comes from “dormitorium,” which means “a place for sleeping.” Dormers are often added to unfinished attic spaces to convert them into bedrooms.

9 Types of Dormers

The style of your dormer's framing should match the architecture of your home. Some gables feature individual windows and look as if they sprung up out of your current roof. Others significantly alter the shape of your home, extending from end to end with multiple windows on one dormer. Just as you would a house, the type of dormer will depend on what both looks best and offers the most practical solution.

Gabled Dormers

Gabled dormers are the most common styles, blending with both modern and historic homes.

• Includes one window per dormer

• Peak at the top and slope down on either side

• Sit perpendicular to the roof's slope

Shed Dormers

Maximize the headroom in your attic by connecting windows into one long dormer.

• Roof slopes toward the front of the house

• Links several windows together into one dormer

• Maximizes the living space on the top floor

• Roof of dormer has a flatter pitch

Hipped Dormers

Once you get to know the types of roof styles for your home, you'll recognize the hipped style that slants upward on both the front and the sides of the dormer.

• Ideal for hipped-roof homes

• Increases headroom on the top floor

• Requires more roofing materials

Recessed Dormers

While these dormers come in a range of roof styles, they are always set back into the structure of the main roof to extend the walls.

• Blends more seamlessly with the home's roof

• Commonly called inset dormers 

• Requires fewer building materials

Eyebrow Dormers

Curved dormers offer a softer aesthetic, as if they’re popping out of the home like eyebrows.

• Sit atop single or multiple windows

• Ideal for roofs with curved shingles to mimic thatching

• Adds light to top floors but minimal space

Extended Shed Dormers

An extended shed dormer is an extension of the wall below. It may also be bumped up from the roof plane.

• Adds a significant amount of interior space

• Keeps the footprint of the home

• Emerged in the 1660s but remains a popular style

Reverse Dormers

Also known as an inverted or inset dormer, a reverse dormer inverts from the roof rather than protruding out from it. 

• Often used for patio or garden spaces

• Adds detail to the roofline

• Creates a Tuscan look

False Dormers

A false dormer is a faux window that comes out of a roof. While it’s not meant to be functional, it does add symmetry and detail to a home.

• Looks like a real window from the outside

• Creates a grand appearance

• Doesn’t allow any light into the home

Pedimented Dormers

While a pedimented dormer is similar to a gabled dormer, it incorporates Greek and Roman architecture. 

• Protrudes outward horizontally

• Uses molding to showcase a triangular shape

• Considered a classic version of a gabled dormer

What Is the Purpose of a Dormer?

The intent of a dormer is to add more natural light through the use of a window and/or to add more usable space to your floor plan. A dormer will either increase the ceiling height in a room or, if large enough, add more square footage.

Dormers can also become an important design feature, enhancing the character and interest of your home’s curb appeal.

Pros and Cons of Roof Dormers

The cost to finish an attic can be tricky to balance, especially when turning such an often-cavernous space into a welcoming living area. Dormer windows offer a budget-friendly approach compared to altering the height of the roof. That being said, there are ups and downs to dormer additions that are important to consider. 

Pros

If you have a great contractor on your side and they give you the green light to add a dormer addition, here are some of the things to look forward to.

• Increase usable square footage on your top floor

• Adds natural light to the space

• Increase ventilation in the attic

• Boosts curb appeal by breaking up your roof's design

• Can add resale value to your home

Cons

On the other hand, remember that major structural changes to your roof can be costly and will often require more upkeep to handle the elements.

• Dormer additions cost an average of $12,000 each

• May not be an option for older and more fragile roofs

• Often requires additional gutters

• Depending on the design, it can lead to more leakage

• Not a DIYable project

What Size Should Dormers Be?

There is no set standard on sizing dormer additions. Ultimately, it will come down to what looks best on your home and achieves the extra space or lighting you desire.

You will need to consider factors such as spacing between dormers, the slope of your current roof, the proportions of your home, the size of the windows you will use, and the codes for required egress. 

To properly size your dormer additions, work with a licensed architect near you who will take all of these design factors into consideration.

How Much Does It Cost to Add a Dormer to Your Roof?

The cost to add a dormer ranges from $2,500 to $20,000, with an average cost of around $12,000. Be sure to look into your options for how to finance a home addition to ensure it's the right move for you at this time.

The type of dormer you choose to install has a significant influence on the cost, the project size, and any required permits. Keep in mind most dormer additions will provide a return-on-investment of about 40% due to the increase in usable space. 

What to Consider Before Adding a Dormer to an Existing Roof

Before you set out to install dormers on your home, consider these factors that could influence your decision.

Not All Roofing Systems Are Compatible With Dormers

Depending on the type of structural roof framing you have, adding dormers to your house may prove difficult. Request a visit from an experienced general contractor to discuss the feasibility of a dormer addition project.

You may need to install additional structural framing in order to support new dormers, which will significantly add to the overall cost.

Dormer Additions Are Not a DIY Project

Adding a dormer to your home is a huge undertaking. It involves altering structural components and installing watertight seals. If these tasks are done improperly, it can lead to unsafe living conditions and costly repairs down the road.

Dormer additions are a project best left to the professionals. Contact a local roofer near you to discuss the possibility of adding dormers to your home.

Dormers Can Be Prefabricated or Custom-Built

If your home has a simple roofline and you want a standard dormer size and style, a prefabricated dormer is a good option to consider.

Prefabricated dormers are already framed, insulated, and roofed. They are first set with a crane and then a contractor will finish the installation with proper flashing and siding.

If you have specific design or sizing preferences, you are better off with custom-built dormers.

Dormers Are Sometimes a Source of Leaks

The sidewalls of dormers can be a source of leaks. This can happen if a general contractor who isn’t a roofer doesn’t properly flash the area. Roofing pros recommend hiring a roofer to handle the sidewalls of the dormer—even if a contractor builds the dormer itself. A roofer will likely use step flashing for the dormer’s sloped walls, as well as an ice and water shield up the wall behind the siding.

Ginny Bartolone contributed to this piece.