A construction worker inside a partially-completed house.


A roof is more than just a bunch of shingles placed on top of each other. In fact, many modern roofing systems can be pretty complex. Understanding the different parts of a roof can help you better understand which parts need to be replaced or repaired in your home.

Roof Terminology 101

Most roofs have some variation of the following parts:

  • Shingles
  • Underlayment membrane
  • Decking (Sheathing)
  • Ridges
  • Valleys
  • Flashing
  • Roof Edges (Eaves)

Whatever your home’s roof is like, it probably has more components than meet the eye. It takes an interlocking system of roof parts to keep your home protected from the elements. We’ll break down what these terms mean and why they’re essential below.

Graphic showing the different layers of a roof and their terms.


Shingles form a roof’s topmost layer. They are typically made out of asphalt or fiberglass, and they give the roof its distinct dark color. The thicker the shingles, the higher the quality, given their increased resistance to weather changes.

Ideally, shingles will absorb most of the sun’s heat in the summer months and help keep the inside of a house cool. Most asphalt shingles also come with a 100% coverage warranty for the first few years. Newer shingles even come with warranties against algae development. Instillation of shingles is with a vertical overlap. This way, water will travel from one shingle to the top of the next one and prevent any leaking.

Underlayment Membrane

This is the layer directly below the shingles. It adds additional waterproofing protection but also helps prevent the shingles from coming into contact with any resin released by the wood decking frame. It also helps protect that very same wood frame from weather. By the time you reach the underlayment, you will have already achieved a decent amount of waterproofing.

Decking (Sheathing)

Decking is the layer directly below the underlay membrane. The decking is the wooden ½ inch plywood which provides a flat surface for the singles to rest on. It also creates a platform to nail the shingles into.

Supporting the ½ inch plywood is the actual frame of the roof, which is what gives a roof its distinct shape and pitch. It is typically possible to see the supporting frame from inside the attic.

A construction worker on a partially-completed roof. Text: The decking is the wodden 1/2 inch plywood which provides a flat surface for the shingles to rest on.


The ridge is the peak or crest of the roof. It is the tip of the triangle and is the highest point on the structure.


A valley is the “V” shaped junction where two sloped roofs join together at an angle.


Flashing is a semi-flexible galvanized steel or aluminum strip which is used to prevent water from seeping under the shingles in areas where the shingles end. For example, flashing is commonly used around chimneys to prevent water from getting caught under the shingles. It is also used in valleys to prevent water from seeping through where the two shingles meet.

Roof Edge (Eaves)

Also known as the facia, the roof edge is the bottom-most portion of the roof which. This is typically where gutters are installed.

Questions About Any of Your Roof Components? Contact Us

Knowing the different parts of a roof can help you pinpoint the source of problems as they arise. However, this knowledge alone will not fix the problem. Roof repairs are not a DIY project and are inherently dangerous due to the high elevation of most roofs. We also recommend against climbing up to the roof to visually inspect the problem. It is always safer to call professional roofers to take a look and make any necessary repairs. Call us today for a consultation!

Schedule an appointment or inspection with Legacy Roofing today!

If you would like Legacy Roofing to inspect your roof and offer a free estimate, please call us, or fill out the contract form below. Legacy will send a trained estimator to inspect and offer an experts opinion on the size and scope of your job.

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Servicing All of Northern Arizona

Legacy Roofing

Legacy Roofing LLC - Prescott