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Anatomy of a Roof

Anatomy of a roof

The roof is one of the most important parts of a house. It protects the occupants from the elements and keeps the structure standing. A well-constructed roof will last for many years, but eventually, it will need to be replaced. Here we will take a look at the anatomy of a roof and how it is constructed.

The roof is composed of several layers, each with its own purpose. Here are the most common layers:

  1. The decking: It is the layer that provides structural support for the roof. It is usually made of plywood or oriented strand board (OSB).
  2. The underlayment: This layer waterproofs the roof and protects it from wind and debris. It is usually made of felt paper or asphalt-saturated felt.
  3. The shingles: This is the visible layer of the roof that is exposed to the elements. Shingles are made of asphalt, wood, slate, or metal.
  4. The flashing: This is a waterproofing material that is installed around roof joints and protrusions to prevent water from seeping in. Flashing is usually made of metal or rubber.
  5. Roof Ridge: The roof ridge is the horizontal line where two planes of a roof meet. This intersection creates the highest point on a roof, which is also known as its peak.
  6. Ridge vent: The ridge vent is an exhaust vent that helps to regulate the temperature and ventilation in your attic. It runs horizontally along the peak of your roof, allowing warm and humid air to escape from the attic space.
  7. Hip: A roof hip is where two roof planes come together to create a sloped ridge that extends from the top of the roof to its edge.
  8. Roof Valley: The roof valley is the V-shaped area where two sloping roofs meet at an angle, providing a way for water to run off.
  9. Roof Gable: The gable is the triangle-shaped section of wall at the peak of the roof, where a sloping roof meets an eave. It’s sometimes called a rake.
  10. Undereave vent: Undereave vents are intake vents located under the eaves of your roof. By drawing in cool, dry air, they help to keep your attic comfortable and free from moisture buildup.
  11. Ice and water barrier: Ice and water barriers are put in place to protect your home from ice dams and wind-driven rain. They can be installed along eaves, valleys, side walls, or any other sensitive area of your home.
  12. Dormer: Dormers are raised sections of the roof that commonly contain a window. The window projects vertically through the slope of the roof.
  13. Metal drip edge: A metal drip edge is a thin, noncorrosive strip of metal used on the bottom corners of a building to help with water runoff and protect the section of wall underneath.
  14. Fastener Attachments: Roofing fasteners are used to attach any roofing material to the underlayment or deck. They can be nails for asphalt shingles, metal fasteners for tiles, or bonding adhesive for certain kinds of materials.


The roof is a vital part of any home, and it’s important to understand its anatomy in order to keep it in good condition. The roof is composed of several layers, each with its own purpose. These include the decking, underlayment, shingles, flashing, and other materials. By understanding the function of each layer, you can more effectively maintain your roof and keep it lasting for many years to come, before contacting a professional roofing contractor.