Dormer: Your Ultimate Guide to History, Types & More

by Joost Nusselder | Updated on:  June 13, 2022
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A dormer is a structural element of a building that protrudes from the plane of a sloping roof surface. Dormers are used, either in original construction or as later additions, to create usable space in the roof of a building by adding headroom and usually also by enabling addition of windows.

Often conflated with the term “dormer”, a dormer window is a window set into the dormer. Like skylights, dormer windows are a source of light and ventilation for top floors, but unlike skylights (which are parallel to the roof surface) they also increase the amount of headroom in the room and allow for more usable space.

But first, let’s define what a dormer is and clear up any confusion about whether it’s a window or a roof structure. Keep reading to find out.

What is a dormer

Why Dormers Are the Perfect Addition to Your Home

A dormer is a structure built into a roof, usually containing a window. It is a great way to add additional space and function to your living areas, as well as increase light and ventilation.

Types of Dormers

Dormers can be designed in a variety of styles and types, including:

  • Shed dormers
  • Gable dormers
  • Hip dormers
  • Eyebrow dormers
  • Flat roof dormers

Considerations for Adding Dormers

Adding dormers to your home may require major alterations to the roof and attic. Here are some things to consider before adding dormers:

  • Cost of installation
  • Permission to construct from local authorities
  • Compatibility with existing architecture
  • Impact on energy efficiency

The Evolution of Dormers: From Mansard to Modern

Dormers have been a common feature in architectural design for centuries, appearing in various forms and styles throughout history. The term “dormer” stems from the French word “dormir,” meaning “to sleep,” reflecting the additional habitable space provided by the feature. The earliest dormers were found in Gothic architecture, where spires and lucarnes were used to bring light into the narrow, tall structures. However, it was the French architect Francois Mansart who is credited with developing the Mansard style roof in the middle of the 17th century. This four-sided, double-pitched roof featured a steeply sloping lower section and a stretched uppermost section, providing high attic space for additional living areas without surpassing Parisian height restrictions.

From Residential to Commercial: The Uses of Dormers

Dormers were initially designed for residential homes, but their uses have since expanded to commercial buildings as well. They are commonly found in both modern and traditional architecture, adding natural light and additional space to any structure. There are several types of dormers, including gable, shed, hipped, and eyebrow, each with their own unique features and uses.

From Mansard to Modern: The Changing Styles of Dormers

Over the years, dormers have undergone several changes in style and design. The Mansard roof, which was popular in the 17th and 18th centuries, featured steeply sloping sides and a flat top, making it a popular choice for residential and commercial buildings alike. In the 19th century, the Gothic Revival movement brought about a renewed interest in dormers, with many buildings featuring pointed roofs and ornate detailing.

In the early 20th century, the Arts and Crafts movement brought about a return to simpler, more natural forms, with dormers featuring more organic shapes and materials. Today, modern dormers can be found in a variety of styles, from traditional to contemporary, and are often used to add character and charm to both residential and commercial buildings.

The Future of Dormers: Bringing Light and Space to Modern Architecture

Regardless of the precise style or design, dormers remain a popular feature in modern architecture, providing natural light and additional space to any structure. As architects continue to push the boundaries of what is possible with dormers, it is clear that this architectural feature will continue to play an important role in the design of homes and buildings for years to come.

Exploring the Different Styles of Dormers

While the main types of dormers are fairly standard, there are also several unique styles to choose from. These include:

  • Flared Gable: This type of dormer has a wider bottom than top, giving it a flared appearance.
  • Palladian: This type of dormer has a central window with two smaller windows on either side.
  • Segmental: This type of dormer has a curved roof that follows the shape of an arch.
  • Pedimented: This type of dormer has a triangular roof with decorative elements, such as columns or moldings.

The Crucial Difference Between Dormer Styles

The main difference between dormer styles is the angle of the roof. Depending on the angle, a dormer can be classified as a gable, shed, or hipped dormer. The size and shape of the dormer also play a significant role in its style. Custom dormers can be designed to fit a specific building or rest on a specific level of the roofline. The number of dormers on a building can also vary, with some buildings having plenty of dormers while others have none at all.

Permission to Construct: What You Need to Know

Before you start any construction work on your dormer, it’s important to make sure you have the necessary permissions in place. Here are some things to consider:

  • Planning permission: Depending on the type and size of your dormer, you may need planning permission from your local council. This is especially true if your dormer exceeds certain height and size limits, or if you live in a conservation area. Check with your local council to see if planning permission is required.
  • Building regulations: Even if you don’t need planning permission, you will still need to comply with building regulations. These regulations ensure that your dormer is safe, structurally sound, and energy-efficient. Your builder or architect should be able to advise you on the specific regulations that apply to your project.

Materials and Construction

When it comes to constructing your dormer, there are a few things to keep in mind:

  • Materials: The materials you use for your dormer should match the existing character of your house. This is especially important if you live in a conservation area. Your local council may have specific requirements for the types of materials you can use.
  • Construction: Your dormer should be built to a high standard, using quality materials and workmanship. This will ensure that it adds value to your home and lasts for many years to come.

Size and Space

The size and space of your dormer will affect the permissions you need and the construction work required:

  • Size: If your dormer exceeds certain height and size limits, you may need planning permission. Check with your local council to see what the limits are in your area.
  • Space: Your dormer should provide enough space to improve the internal area of your home. This may involve creating extra headroom or adding a new floor to your house. Your builder or architect should be able to advise you on the specific space requirements for your project.

Types and Styles

Dormers come in many different types and styles, each with its own specific requirements:

  • Straight dormers: These are the most popular type of dormer and are relatively easy to construct. They provide extra headroom and space, and can be used to create a loft conversion or extension.
  • Modern dormers: These are a more contemporary style of dormer, often featuring large windows and clean lines. They can add a touch of modernity to an older property.
  • Special dormers: These are dormers that have specific features or requirements. For example, a conservation dormer may need to be built using traditional materials and styles to match the rest of the property.

Fall and Height

The fall and height of your dormer will affect the permissions you need and the construction work required:

  • Fall: Your dormer should be designed to ensure that rainwater falls away from the roof and doesn’t cause any damage. Your builder or architect should be able to advise you on the specific fall requirements for your project.
  • Height: If your dormer exceeds certain height and size limits, you may need planning permission. Check with your local council to see what the limits are in your area.

Existing and Proposed Limits

When planning your dormer, it’s important to consider the existing and proposed limits:

  • Existing limits: Your dormer should be designed to match the existing character of your property. This may involve using specific materials or styles to ensure that the dormer blends in with the rest of the house.
  • Proposed limits: Your dormer should be designed to provide the space and features you need, while still complying with planning permission and building regulations.

Calculating the Cost of Your Dream Dormer

Before you start dreaming of a cozy reading nook or a luxurious bathroom with a shower in your new dormer addition, you need to consider the following factors that will affect the cost of installation:

  • Size: The larger the dormer, the more materials and labor will be required, which means a higher cost.
  • Type: Different types of dormers, such as gable, hip, shed, or eyebrow, have different designs and require different materials and labor, which affects the cost.
  • Roof pitch: The steeper the roof pitch, the more difficult it is to install a dormer, which means a higher cost.
  • Accessibility: If your roof is hard to access, such as a steep or high roof, it will require additional safety measures and equipment, which will increase the cost.
  • Permits: Depending on your location and the size of your dormer, you may need to obtain permits from your local building department, which can add to the cost.

Getting Accurate Estimates for Dormer Installation

To get accurate estimates for dormer installation, you should:

  • Research local contractors: Look for licensed and insured contractors who have experience with dormer installation.
  • Request quotes: Contact at least three contractors and request written quotes that include labor, materials, and permit costs.
  • Compare quotes: Compare the quotes and make sure they include all the necessary details, such as the type of dormer, the size, and the timeline for completion.

Roof Dormers: The Good and the Bad

  • Increased indoor space: Dormers can add significant space to a room, making it more livable and comfortable.
  • Natural light and ventilation: Dormers create inflow of sunlight and air, which can make the room feel cool and airy.
  • Adds value to your property: The added space and style that dormers bring can increase the value of your property.
  • Differentiates your house: Dormers can give your house a unique look and differentiate it from other houses in the neighborhood.
  • Provides access to attics and upstairs areas: Dormers can be installed to provide access to previously unused areas of the house.

Important Points to Remember

  • The style and type of dormer you choose can affect the cost and benefits.
  • Dormers can be placed on different parts of the roof to create different effects.
  • Dormers can help increase the natural light and ventilation in a room, making it more comfortable to live in.
  • Dormers can be a small feature that adds significant value to your property.
  • When considering dormers, it’s important to take into account the local regulations and requirements for installation.

Frequently Asked Questions About Dormers

There are several types of dormers, but the most common ones are gable, shed, hipped, and eyebrow dormers. Gable dormers are the simplest and most common type, featuring a triangular roof that protrudes from the main roof. Shed dormers have a single sloping roof and are often used to add more headroom to a small room. Hipped dormers have a roof with three sloping sides and are commonly used in buildings with a hip roof. Eyebrow dormers are ornamental and have a curved roof that blends with the main roof.

What materials are used to construct dormers?

Dormers can be made from a variety of materials, including wood, vinyl, and metal. The choice of material depends on factors such as the quality of the material, the architectural style of the home, and the budget. Wood is a popular choice for its classical touch and can be painted to match the exterior of the home. Vinyl is a low-maintenance option that is resistant to moisture and can be paired with sliding glass windows. Metal dormers are durable and can be made from materials such as copper, zinc, or aluminum.

What is the purpose of a dormer?

Dormers serve both a functional and aesthetic purpose. Functionally, dormers allow for more natural light and ventilation in a room. They can also be added to provide more headroom in a small attic or to create a new room in the attic. Aesthetically, dormers can add balance and interest to the exterior of a home. They can also be purely ornamental, referring back to the masterpieces of the Greeks and their structures.

What is the difference between a dormer and a window?

A dormer is a small structure that protrudes from the roof of a building, while a window is an opening in a wall or door that allows light and air to enter a room. Dormers enclose a window or a series of windows and are typically added to the roof of a building, while windows are installed in the wall or door of a building.

What is an accordion attic ladder and when is it used?

An accordion attic ladder is a type of ladder that is used to access an attic or loft space. It is called an accordion ladder because it folds up like an accordion when not in use. This type of ladder is often used in homes with limited space, as it can be easily stored in a small closet or corner.

What is the best way to maintain a dormer?

Maintaining a dormer involves regular cleaning and inspection to ensure that it is functioning properly and not allowing moisture to seep into the home. Some tips for maintaining a dormer include:

  • Cleaning the gutters and downspouts regularly to prevent water damage
  • Inspecting the shingles or other roofing material for damage or wear
  • Checking the caulking around the windows for cracks or gaps
  • Replacing any damaged or worn parts, such as the shingles or sliding windows

Dormer vs Gable: Which One Fits Your Home Design?

When it comes to building designs, dormer and gable are two of the most common types of windows. But what are the differences between the two?

  • A dormer window is a protruding window coming out of the roof of the house, while a gable window is a flat window on the flat end of the house.
  • Dormers come in a lot of different designs and shapes, while gable windows are simple and have only one shape.

Adding Dormers or Gables: What to Consider

If you’re considering adding dormers or gables to your home, there are a few things you need to keep in mind:

  • Adding dormers or gables requires some skills and knowledge in roofing and construction.
  • The size of the area where you want to add dormers or gables will determine how many you can add and what size they should be.
  • You need to be prepared for the case that adding dormers or gables may require permission from your local authorities.

Dormer and Gable Designs: Examples and Types

Here are some examples of different types of dormers and gables:

  • Dormers: shed, gable, hipped, eyebrow, wall, flat, mansard, and more.
  • Gables: cape cod, midcentury, fancy, empire, françois, modified, gambrel, and more.

Dormers and Gables: Function and Features

Here are some features and functions of dormers and gables:

  • Dormers are known for their ability to add more light and space to a room.
  • Gables are often used to shield windows and openings from rain and snow.
  • Both dormers and gables can be waterproofed with flashing and tarp to prevent leaks.

Dormers and Gables: A Brief History

  • The earliest known examples of dormers date back to the elegant and regal Chateauesque style of the Biltmore Estate in North Carolina.
  • Gables have been a common feature in American architecture since the colonial period.
  • The French invented the mansard roof, which is a type of dormer with sloping sides forming a triangular section, and the gambrel roof, which is a steeper version of the mansard roof with two sloping sections meeting at a ridge.

Dormer vs Skylight: Which One to Choose?

Dormers are structures built onto the roof of a building, with walls and a roof as well as a window. They are typically vertical and placed on the sloping surface of the roof. Skylights, on the other hand, are windows that are installed directly into the roof surface. They are usually inclined at a certain angle to allow for better lighting and ventilation.

Installation and Maintenance

Installing a dormer is generally more difficult and expensive than installing a skylight. It requires extra material and follows certain parameters to ensure the quality of the building. Maintaining a dormer is also more complex, as it involves regular upkeep of the walls and roof. Skylights, on the other hand, are easier to install and maintain, as they are usually covered with a simple glass or plastic surface.

Lighting and Atmosphere

Dormers provide a wide range of lighting options, as they allow light to spread uniformly across the room. They also provide a comfortable atmosphere, as they reduce the total height of the room and provide a sill for sitting or placing objects. Skylights, on the other hand, provide interesting lighting options, as they let in natural light and allow for airing during the winter. However, they can also cause overheating in the summer if not covered properly.

Advantages and Disadvantages


  • Provides extra space and functional room
  • Adds value to the building
  • Influenced by personal taste and style
  • Requires extra installment and roofing
  • More expensive and difficult to install
  • More complex to maintain


  • Provides natural lighting and ventilation
  • Reduces the need for heating and cooling
  • Recommended for attics and rooms with high ceilings
  • Can cause overheating in the summer if not covered properly
  • Easier and cheaper to install and maintain


So, that’s what a dormer is- a structure built on the roof of a house, usually containing a window, and often used for additional living space or for light and ventilation. 

You can add them to your house to add character and charm, and they’re a great way to increase the living space. So, if you’re looking to add some extra space to your house, you should consider adding a dormer.

I'm Joost Nusselder, the founder of Tools Doctor, content marketer, and dad. I love trying out new equipment, and together with my team I've been creating in-depth blog articles since 2016 to help loyal readers with tools & crafting tips.