There are actually two major types of roofs with multiple variations derived from them (except of course flat roofs). These are a Gable Roof and a Hip Roof. Depending on the type, you will need to order a different amount of roofing materials, when you are going to replace your roof. It is equally important for homeowners and contractors alike to know this, as it will affect the total cost of the job.
Depending on the type of roof you have, the replacement price will differ, as will the difficulty of installing the roof, and the amount of waste associated with each type of material. You can refer to our roofing materials calculator to see exactly how much and which materials you will need to order, depending on whether it is a gable or a hip type variation.
Gable is the most common and the simplest type of roof- basically it is a two sloped roof, like an open book, turned upside down. The name “gable” comes from a roof detail, also called rake, the sloped edge of the roof, which you see when standing on the side of a house.
Gable roofs are the easiest to install, especially when they have a rather shallow roof pitch of 3-7, and will have the lowest amount of waste materials. It only gets complicated when you get additional structures on the gable roof, such as dormers / shed dormers, valleys, etc. Then the amount of flashing and other detail work increases.
Hip is the second roof type, which resembles a pyramid. Hip roofs have four planes which connect on the corners of each side of the roof. A typical hip roof will have two triangular sections on shorter sides, and trapezoid sections on longer sides of the roof. A square hip roof will have 4 triangular sides, and will represent a perfect pyramid.
It is important to note, that when you measure a hip or a gable roof, assuming that ground dimensions and roof pitch are the same, both will have the exact same geometrical size, though common sense may lead you into thinking that a hip roof area will be larger. At the same time, the amount of materials needed for a hip roof and installation cost will be an average 15% higher than for the same size gable roof.
A mansard is essentially a hip roof with high pitch (usually 18 over 12 pitch or more), with the top of it “cut off and replaced with a flat roof. Typically, you will see a flat / mansard roof combination on older multi-story buildings in urban settings. There, a mansard roof is used mostly for decorative purposes. However, it is still a roof, and protects the building from rain / snow and other elements and therefore, it must be treated appropriately.
Mansard roof installation costs are typically higher than for other types of roofs, as there is a lot of detail involved, such as multiple window openings and other decorative details common in 19th and early-to-mid 20th century construction methods.
Other Roof Types and Structures
Shed is another popular roof type, which is essentially half the gable roof, and has only one section or plane, and no real “ridge”. Shed roofs are common on small structures such as storage sheds, and house additions attached to an existing wall of a house.
Dormer is a structure which is attached to an existing roof plane – typically in the center of a roof, and looks like a small house protruding through a roof. A typical dormer has two slopes perpendicular to the roof plane it is on, which creates two valleys where the roofs meet, and a roof to wall connection flashing on the sides and at the bottom of the dormer. Dormers are used to increase the interior space of a finished attic, as well as add more light to the room, by having front windows.
Shed dormer is similar to a normal dormer with the only difference that it has just one roof plane, parallel to the roof section that it protrudes. The slope of a shed dormer is usually considerably lower than that of a roof section it is attached to – otherwise there would not be a dormer.
Shed dormers are used to dramatically increase the interior space in the attic, making it virtually the same as other rooms in the house, with the same ceiling height. A common problem, usually associated with shed dormer roofs, are leaks caused by using inappropriate materials such as shingles. In the northern climates, inadequate roof ventilation / insulation makes shed dormer roofs prone to leaks caused by Ice Dams, which are formed along the eaves (lower edge of the roof) and penetrate the seams / overlaps, causing the leak.
It is recommended to keep a shed dormer roof slope at 3 or more to prevent potential leaks, or use appropriate materials for low sloped roofs, such as a flat roof membrane or a metal roof.
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