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Different Parts of a Roof and Their Importance (With Diagrams)

Different Parts of a Roof and Their Importance (With Diagrams)
Roofs are the crown of any establishment. It not just covers, but even protects the main structure of the building from harsh weather conditions.
Shruti Bhat
Last Updated: Dec 09, 2017
Over the Roof!
The National Botanic Garden of Wales has the largest single span roof in the world. The structure itself is 95 m (312 ft) long and 55 m (180 ft) wide, and the roof contains 785 panes of glass.
The shape and size of the roof depends upon the purpose of the structure, geographical location, and the national and local legislation.

You will often find thatched (sloping) roofs in places with extreme weather conditions. This is to prevent snow and rainwater from accumulating on the roof and ultimately decaying the house. It also works as an excellent reflector against the harsh heat of the sun.

A new trend has been spotted in many a house, and that is to attach solar panels on the roof. This converts the sunlight into useful energy that is used in the homes.
Different Parts of a Roof and their Importance
different parts of a roof and their importance
different parts of a roof and their importance
Sheathings usually consist of wood-like material called oriented strand board or then plywood. Oriented boards are made from the wood of fast-growing trees cultivated specially for the sake of wood. You can also find radiant barriers of sheathing in the market. These are made of aluminum sides, which are laid face down in the attic. This helps to reflect the heat that hits the roof and keeps the house cooler.
Sheathings are panels that envelope the rafters. Other components such as metal panels or shingles are attached to the sheathing later. Sheathing is a layer used as the base of the roof. Other parts of the roof are nailed to this later. This layer covers the rafters and is beneath the shingles and membrane layers.

Using seasoned or dry wood for building the sheathing prevents the wood from buckling or pulling away as the wood dries.
Dormers were initially introduced by French architect Fran├žois Mansart, who also happened to introduce mansard roof to America. This form has been seen in American architecture for centuries.
Dormers are structures set vertically around the windows, which project from the thatched roof. This structure comes with its own roof. The dormers provide additional internal space for the attics while adding to its beauty and character to the house. They suit a wide range of roof types. Gabled, hip, shed, and arched dormers are the most common types of dormers found.
Drip Edge
Drip edge is a piece of plastic, metal, or vinyl that is secured tightly with nails at the bottom of the roof's edge to facilitate water drainage. The drip edge enables water to drain into the gutters and down the fascia. Though available in different materials, it is usually found in aluminum. The drip edge is also one of the first things to be attached to the roof. It should ideally be installed under the roofing felt, with about an inch of overhang extending past the fascia, over the gutters.
Fascia is a horizontal trim board that runs around the end of the rafter. It connects the roofline and soffit. The gutters are attached to the fascia.
Rafters make the main framework of the entire roof, irrespective of the type of the roof. It rests on the main frame of the wall and is inclined up to meet the ridge of another rafter, where they are fastened together. They are usually spaced with 16 - 48 inches between each other.
Rafters often extend beyond the walls and hang to create eaves of the building. Rafters shelter the main structure from the direct impact of rain, sun, and snow. It even helps water and snow to run off and fall farther away from the main foundation of the house.
Common Rafters
These are the beams that extend at right angles from the plate frame of the roof ridge. Other rafters are laid out on top of these rafters.
Jack Rafters Include
Cripple jack: Beams that are placed between hip rafter and valley rafter. This jack does not touch the ridge or the roof plate.
Hip jack: Roof beams that run from the plate to the hip rafter.
Valley jack: Extend from the ridge to the valley rafter.
Hip Rafters
Beams that extend from the corner of the plate to the ridge.
Valley Rafters
The roof beam that extends from the corner of the plate to the ridge along the intersection between the two sides of the roof.
Ridge and Ridge Vent
Ridge is at the top of the roof where the two sides meet and form an angle. This runs down the length of roof. Ridges need to be shingled or caped to keep the water from trickling into the main frame of the house.

Ridge vents are installed to keep the attic ventilated and run along the length of the ridge. It also helps the warm air to escape the house and prevents moisture from building up. Ridges are mostly capped with ridge cap shingles to maintain an even appearance.
Roof Truss
Truss is the framed set of rafters that supports the roof of the house. This provides the roof with immense strength. This also gives a wide variety of shapes and design for the roof.
Soffit is the horizontal area under the roof overhang. It is left open past the main walls of the house; however, they are closed off to give a finished look.
Starter Strip
It is a row of shingle material that is applied under the primary shingle and on top of the drip edge and underlayment. It has 2 main purposes: (i) to protect the shingles from wind at the bottom of the roof; (ii) to fill the spaces in between the tabs of most shingles in order to cover every inch of the sheathing.
Underlayment initially meant felt paper or builder's felt, which was soaked in asphalt. However, nowadays, you get the underlayment in synthetic material, which makes it more resilient to wear and tear and moisture.

Underlayment is the second layer of protection for the roof. It is applied directly to the roof sheathing to protect the roof from the elements while shingles are fixed to the roof. Once fixed, the underlayment will help repel the moisture.
A valley is defined as the area where two roof fields join to make an inward angle. This is also an important part of the roof, failure to which can cause leaks and rotting of the roof and house.
Field of Roof
Field of roof is the central and main portion of the roof.
Chimney and Chimney Saddles
Chimney is connected to the fireplace to escort the smoke out of the house. It is a narrow vertical exhaust, a few feet higher than the main roof.

Chimney saddles are two sloping surfaces meeting at the horizontal ridge between the back and side of the chimney.
Low-profile Attic Vent
It assists in low penetration ventilation.
Space Inside
Space inside is the open area above the ceiling under the roof deck of any steep-sloped roof.
Skylight and Sky Saddles
Skylight is a window in the roof made to allow the daylight to stream in, whereas a sky saddle is a saddle-shaped frame connecting a sloping roof to the skylight.
Flashing or step flashing is a flat sheet of metal or plastic that is nailed over the cracks between the chimney and the main structure of the house.
Rake is an inclined edge of a roof on top of a wall.
It is the lower part of the roof that extends beyond the side of the house.
Gutters are vents that carry away the trickled rainwater.
Plumbing Vent
It is a device used on the gabble, roof, or soffit to provide ventilation to the underside of the roof deck.
Joist is the horizontal supporting member, which runs between beams, foundations, or walls to support a ceiling. It is made from wood, steel, or concrete.