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Understanding the Anatomy of a Residential Roof

A diagram of different components of a roofing structure

It will be an enormous benefit to you to know the anatomy of a roof before or after you select a roofing contractor.

Residential roofs are more than just the visible part. It is a complex system of layers and structures that protect your property. Understanding the anatomy of a roof can help you understand the importance and benefits of roof upgrades and repairs. Your roof's optimal condition will help prevent water damage and structural problems.


Depending on the materials used, a roof can last between 20 and 50 years. Invest in high-quality materials and find a reputable roofing company close to you, such as Arrow Point Roofing & Gutter. They will provide excellent workmanship.


The basic structure of a residential roof is a frame, which gives it its shape. This structure is composed of beams known as joists, braces, and trusses. This frame will support all other parts of the roof.

The sheathing (or roof decking) is a layer made up of flat wooden boards, usually plywood or planks, or an oriented strand board (OSB). The other roofing materials can be attached to this flat structure. If your sheathing is damaged or rotten, you will need to replace it.

The underlayment is the next layer. This is a membrane-like material that provides extra protection from water. It is installed between the sheathing and shingles. It is often made from felt. Synthetic materials are becoming more popular and can even be used to protect from ice.

The covering is located above this structure. This is the visible portion of the roof. This can be made from metal, slate, steel or asphalt shingles.


Roof flashing, roof flashing and roof vents are all common components.

Shingles are small, interlocking or overlapping tiles that are used to cover a roof. They can last between 25 and 50 years.

The ridge cap is triangular bent material that is installed above valleys or hips on a roof. This ridge capping is easier to see at the top of a roof. It covers the gap which, if not covered properly, can be susceptible to water leaks.

The roof vents ventilation and heats the attic to prevent moisture and heat from damaging roofs. Airflow allows hot air to escape and extends the roof's lifespan. The attic space is between the ceiling and roof.

The roof flashing is a thin metal material which directs water away from joints and seams and towards gutters. Roof flashing seals roofs and prevents leaks. Most commonly, they can be made from plastic, aluminum, and steel. They can last for up to 30 years.

Knowing the different components of your roof is really helpful when contemplating a roof repair or roof replacement for your Spokane home. Of course, Arrow Point Roofing has experienced roofers who can evaluate your roof and provide a free estimate explaining exactly what condition the various components are in and explain what repairs or mitigation should be done.

Arrow Point Roofing & Gutters offers free estimates and financing for homes and businesses throughout the Inland Northwest. We are a family-owned, locally owned, Spokane roofing and gutter installation company, and we will always set clear expectations and communicate with you before, during and after the job!

Call Arrow Point Roofing at (509) 504-6972


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