Roof Dormers, an integral and important part of a roof’s structure, have many different types and styles that people would like to add to their houses. Some look good, while others serve a purpose. Roof dormers can improve your home’s architectural appearance, add living space, and provide other advantages. This article discusses the many types of dormers and how much they cost to construct.
What is a Dormer?
A Dormer is a windowed structure projecting from the sloping side of a roof to provide additional space in the rooms. While sometimes it takes the form of an ordinary square or rectangular box with hinged doors or windows toward its upper edge, more frequently, it rises in the form of a triangular prism with its area lighted by one or more windows along each side. It often occurs as part of an architectural design; however, it is frequently used for functional purposes. Dormers can be placed both on gable roofs as well as on roofs that are bell-shaped or flat.
In residential areas, gabled dormers are a common design element and usually serve for roof drainage. When designed as a purely aesthetic feature, a gable roof with a wood-framed dormer can be aesthetically pleasing – particularly if it is decorated by ornamental finishing – especially when combined with other elements such as shutters or window boxes.
Why should you add a dormer?
Visual Appeal: Dormers add to the aesthetic appeal of your house. They have the potential to enhance your home’s beauty.
More Room: Adding a dormer to your house can increase your living area without adding the cost, time, and inconvenience of moving.
Dormers sometimes allow you to make smart use of space that would otherwise go underutilized. For example, a rooftop addition with a skylight or dormer can give you attic storage and an extra closet, bathroom, or bedroom for little expense.
Safety: A dormer makes an excellent place to install a patrol or fire watch station for security and safety reasons. In emergencies, a dormer can become a refuge, an observation post, an exit point, or even a make-shift bedroom window.
In addition to adding square footage, a dormer can make a space seem more open and accessible by decreasing the slope of the roofline and opening up a room’s vertical dimensions.
With a traditional gabled roof, a dormer is an attractive way to achieve this effect without raising the height of the entire structure – which would necessitate a steeper roof, which would, in turn, create some additional cost and potential inconvenience.
More Natural Light: Adding dormers is also used as a way of increasing light and ventilation. For instance, adding dormers on each side of the roof can bring light into an otherwise dark attic.
Why should You not add a dormer?
Most roof dormers will cost you between $100 and $200 per square foot, depending on the size and complexity of construction. This estimate includes all exterior materials such as siding, brickwork, trim, windows, and doors. It does not include interior work such as drywall ceilings or flooring finishes.
If you dedicate an entire room to a dormer, it can add significant value to your home. Likewise, if you add a bedroom or an extra space for living, the money you’ll spend on the project will be recuperated when you sell your house.
The structure makes it more difficult for you to paint or repair the exterior of that side of your house, and it may reduce your home’s overall structural integrity. If you live in an area with heavy snowfall, you will need to make sure that all the components of your dormer, including the roofing material and its flashing, are engineered to support your area’s snow load. This can be particularly problematic if you intend to use your dormer as a rooftop escape hatch – adding this extra element will significantly increase your house’s weight. In addition, they may require that you reinforce the structure for safety reasons.
Moreover, dormers are not energy efficient. Although they can provide you with extra living space, dormers prevent your roofing system from properly ‘breathing.’ Dormers interrupt the insulation, which traps heat inside or reduces heat loss. Because of this problem, many homeowners choose not to use them for bedrooms or bathrooms.
Types of Dormers and Their Costs
Different types of dormers are used in architecture to provide more space on the second floor or attic level of a home. A properly designed dormer makes the best use of the roof’s surface area while still allowing for adequate headroom inside the finished dormer.
There are twelve to fifteen different types of dormers; Gable Roof, Flared Gable, Hip Roof, Arched Top, Eyebrow, Flat Roof, Shed Roof, Wall Roof, Curved Roof, Pedimented, Recessed Roof, Pyramidal Roof, Polygonal Roof, Dormers with Multiple Planes, Dormers with a Palladian or Double-Hung Window, and False or blind dormer. The cost to construct a roof dormer varies depending on the type of material used for construction and how many sides or angles it has with its structure. Each type of dormer is discussed below in greater detail, along with their associated costs.
1. Gable Roof
In a gable roof, the interior space is divided into two equal-sized cubes or rooms. In the simplest type of gable, called a ‘triple gable,’ each cube is triangular and separated by an internal wall that runs parallel to the slope of the roof – just like the walls of the main house.
If you intend to convert an existing room into a gable roof dormer, you will have to remove the ceiling. This creates more volume in the space, which allows for more natural light and ventilation. A gable roof dormer can be any size, including very small or large, depending on your preference and the space available. It is the cheapest type of dormer to build, costing around $100 per square foot for labor and material. The gable roof has a pitched roofline. The walls on each side of the dormer slope at approximately 30° from floor to ceiling.
2. Flared Gable
A flared gable includes an outward-angled side wall at the top of a gable roof. The flared design is popular for creating additional living space in garages and sunrooms. The flared gable can also be used over an existing opening such as a window or door, but the design may require more complex framing and shingles. On the other hand, a flared gable dormer can be a cost-effective way of creating additional space in your roof area and is the least expensive type at around $75 per square foot for labor and material. A flared gable requires more labor than a standard gable dormer but costs about the same to build.
3. Hip Roof
A hip roof has four sloping sides that converge at a central ridge instead of two sloping sides that meet at a peak, as in a gable roof. Hip roofs are more difficult to construct than a gabled or flared gabled dormer because they require more complex framing and installation of sheathing material. However, a hip roof dormer can be more aesthetically appealing than other types of dormers and may cost slightly more to build. Since the former is located on the sloping portion of the roof, there’s less space on top of the dormer for a room – usually just enough to fit a window. It costs around $150 per square foot to build.
4. Arched Top
Dormers with an arched roofline provide more interior headroom than a gable or flared gable roof since the roof slope is less steep. However, when adding an arched roof to an existing room, you will have to remove part of the existing ceiling.
Construction is difficult and requires special tools, but an arched roof dormer can be built with common household tools like saws, hammers, mallets, drills, levels, and chisels. An arched roof costs around $175 per square foot for material and installation. The walls on each side of the dormer slope at approximately 50° from floor to ceiling.
An eyebrow dormer has a flat roof and is arched like an eyebrow at the top, where it meets the sloping portion of the roof. This design provides more room for a bedroom with additional headroom, but unless the existing roof structure is strong enough to handle more weight, this type of dormer cannot be added. Eyebrow dormer costs around $150 per square foot for material and installation. The walls on each side of the dormer slope at approximately 50° from floor to ceiling.
6. Flat Roof
The flat roof and walls on an eyebrow dormer make it similar in construction to a shed or pent roof – both very easy to build with common household tools. There’s no pitch to the roofline like a shed or pent roof, so there isn’t as much room for a bedroom as there is on an arched dormer. However, installing a flat roof on a gabled or flared gable dormer may be less expensive than building a shed or pent roof. A flat roof costs around $100 per square foot for labor and material. The flat roof has no pitch lines but does have walls on each side of the dormer that slope at approximately 30° from floor to ceiling.
7. Shed Roof
A shed dormer is wide and shallow in shape, usually about two feet across or less. This small, low-pitched roof often covers an unenclosed space such as a staircase or an alcove. The shed dormer provides plenty of headroom for a small bedroom, but because it has no walls on either side to provide privacy, this design works best when the dormer is placed on a secondary home like a guest house or in-law apartment. Like shed dormers, pent roofs typically cover unenclosed spaces and only require two walls and a roof (no floor) to construct. The cost of building a shed or pent roof is approximately $60 per square foot for labor and material, including installation. The walls on each side of the dormer slope at approximately 20° from floor to ceiling.
7. Wall Roof
A wall roof with a gable style can be built with common household tools but takes more time. Installing a wall roof dormer is like adding another layer of walls on the sloping side of the roof. Since gable roofs are typically used on homes, dormers with this style are often integrated into the original design. Wall roofs cost around $150 per square foot for labor and material. The walls on each side of the dormer slope at approximately 30° from floor to ceiling.
8. Curved Roof
A curved roof is more difficult and laborious than a gable or wall roof but provides more headroom inside the finished dormer. Building a curved roof dormer requires cutting and installing rafters that are cut at angles. The gable ends of the roof are then framed with plywood. A curved roof costs around $200 per square foot for labor and material. Since the walls on each side of the dormer slope are at greater than a 45° angle, you’ll have to cut part of the existing ceiling out to accommodate them.
9. Pedimented Roof
A pedimented roof is a wall dormer with a low-pitched, gable-style roof and an elaborately shaped triangular window. This dormer type is often found in luxury homes, so it’s usually part of the original design. Pedimented roofs are difficult to build with household tools but can increase your property’s value as much as adding a second story. A pedimented roof costs around $275 per square foot for material and installation.
10. Recessed Roof
A recessed roof is constructed with four walls and a low-pitched shed-style roof. It can be added to an existing room or used as a stand-alone structure. For example, you can add a recessed roof to the back of an existing home. The cost of building a recessed roof is about the same as for other types of wall dormers – around $160 per square foot for labor and material.
11. Pyramidal Roof
A pyramidal roof, also known as a witch’s hat, is the most difficult type of dormer to build. This type of dormer is made with four walls and a gable-style roof. Like other gable-style roofs, the sides of this roof are high and steep, but the roof is low in the center. Therefore, it requires special tools and a lot of skills to build. A pyramidal roof costs around $400 per square foot for material and installation. The walls on each side of the dormer slope at approximately 40° from floor to ceiling.
12. Polygonal Curved Roof
A polygonal curved roof, also known as a barrel, has a round or octagonal shape. It’s a difficult type of dormer to build with household tools, but it provides ample headroom for a room. It’s hard to purchase roofing materials in this curved design, but you can use corrugated polycarbonate roofing panels to mimic the look. This type of dormer requires special tools and a lot of skill to build. A polygonal curved roof costs around $500 per square foot for material and installation. The walls on each side of the dormer slope at approximately 50° from floor to ceiling.
13. Dormers with Multiple Planes
When space is limited, you can create several planes on a single wall separated by decorative moldings or flat horizontal panels. The overall effect looks like several dormers but only takes up the space of one. Each plane can be the same size or different sizes. It costs around $100 per square foot to build and $175 per square foot for installation labor and material.
14. Dormers with a Palladian or Double-Hung Window
The classic image of this dormer type is a triangular, gable-style roof topped by a window with a semicircular arch above it. A Palladian or double-hung dormer is difficult to build and laborious to install, but it looks stunning. It costs around $275 per square foot for material and installation.
15. False or blind dormer
A false dormer, also known as a facia board or decorative gable, is sometimes used on the front of a house to appear more symmetrical. It is constructed of wood or brick but has no window or other opening, just a decorative appearance. A false dormer costs around $100 per square foot for material and installation.
On a concluding note, although it may seem like a simple proposition to throw up an extra roof on your home, the laws of physics will still apply. Extra load-bearing walls might be necessary, and you’ll need to make sure that exterior walls can support the extra weight. You’ll also want to ensure that any supporting walls, windows, or other features will continue to line up correctly with the new dormer. Finally, don’t forget to consult a structural engineer if you’re in doubt about anything. Verify your building plans, make sure any new structures meet code and sign off on the plans before breaking ground.