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Everything You Need to Know About Roofing, Part 1: Roofing 101

It keeps you safe from all kinds of weather and critters — but how? Get to know all the elements of your roof and popular designs before you replace it.

ByJuliana McDonald| Last Updated:06/09/2023
A man hammers asphalt shingles on a roof.

A Complete Introduction to Roofing Terms and Design

The roof of your home can account for up to 40% of your home’s exterior. From curb appeal to home safety, it’s important to understand what keeps your home looking sharp and (more importantly) dry.

Most homeowners will need to replace a roof at some point, but many don’t know where to start. That’s why we’ve outlined the most common roofing terms and components you should know before starting any roofing project.

What Is a Roof Made Of?

There are seven basic roofing components you should be familiar with:

Shingles: There are several types of shingle materials, but their main purpose is to protect underlying sheathing from the weather. Shingles are traditionally measured in squares. A square of shingles is 100 square feet, so if you know your roof is 2,500 square feet you will need to order 25 squares.

Sheathing: Boards or sheet material that are attached to the rafters that cover your home. This is also referred to as the deck of a roof.

Trim: Installed to protect the seam in the roof along a hip or ridge.

Rafters: These are the wood or metal slats inside your home that support the sheathing and shingles. They’re a bit like the skeleton for your roof.

Underlayment: Water-resistant, paper-like material that is laid over plywood sheathing to seal it from damaging elements such as rain and snow. This is used with a membrane and vapor barrier, which is typically a sheet of plastic blocking air and water from leaking through.

Flashing: Sheet metal or other material installed on top of the joints of a roof system to prevent water damage. The joints of your roof are anywhere it changes direction, and flashing is used to help seal these points off from the elements.

Drainage: This is a roof design feature that allows it to shed water. This is measured using the slope, or pitch, of the roof, which is determined by the rise in inches for each foot of horizontal distance — known as the “run.” For example, a roof with a 5-in-12 slope rises five inches for every foot in distance.

Dumpsters.com infographic showing the eaves, gable wall, abutment, ridge, centerline of ridge, valley, hip and dormer of a roof.

8 Common Roof Design Elements

After you understand the components that make up your roof, it's important to identify the roofing design elements that apply to your home.

Gable Wall: Triangular portions of the home which extend from the eaves to the peak of the roof.

Centerline of Ridge: Also called the verge, this refers to the wall or rafter under the edge of a roof where a gable ends.

Ridge: The highest point of the roof, which is also referred to as the peak.

Valley: The areas of the roof where two sections meet and slope down.

Eaves: Edges of the roof that hang over the exterior walls of a home.

Hip: A high point where two sections of the roof meet.

Abutment: Where sections of the roof meet a vertical area such as a wall or chimney.

Dormers: Not every roof has them, but these are sections of the home that stick out from the roof, designed to bring in natural light to an attic or third floor.

Take a look outside and check which elements your roof has, noting how many ridges, hips, abutments and gables are present. If you’re considering a roof replacement, it’s important to understand the square footage and design of your existing structure to estimate the cost.

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5 Questions to Ask Before Replacing Your Roof

1. When Was Your Roof Installed or Repaired Last?

Does your home have the original roof, or were repairs made within the past few years? Depending on the type of shingles you have and the age of your roof, you may need to keep an eye out for leaks or even schedule a replacement. When your roof needs to be replaced will depend on the existing structure and shingle type. Asphalt shingles will hold up for 20 years, while wood shake roofs can last up to 30.

2. How Is Your Roof Ventilated?

Proper ventilation is important for a healthy roof system. If your roof lacks air flow it may be susceptible to mold and mildew. In addition to a main vent in your roof, there are a few other factors that affect how air moves through your attic to the roof.

Check your attic for the following:

  • A gap-free layer of insulation on the attic floor to protect the house from heat gain and loss.
  • A vapor barrier under the insulation and next to the ceiling to stop moisture from rising into the attic.
  • Enough open, vented spaces to allow air to pass in and out freely. Typically, a roof should have one foot of vent space for every 150 square feet of attic space.
  • A minimum of one inch between the insulation and roof sheathing.

3. What Type of Shingles Do You Have?

A variety of materials can be used as shingles, from asphalt to wood or even slate. Each one comes with a different warranty, and durability depends on your area. Keep in mind that harsh weather conditions, such as high winds or extreme cold, can crack clay shingles.

4. What Is the Fire Rating of Your Roof?

Fire rating is a system for classifying the fire resistances of roofing materials. Classes are labeled A, B and C. Class A materials have the highest resistance to fire that originates from outside of the structure, and these include clay tiles, fiberglass asphalt composition shingles and metal roofing.

5. Do You Know the Pitch of Your Roof?

Pitch, also known as the slope, will determine what type of shingles are best suited for your roof.


Grade of Slope

Recommended Shingle Types


1 - 3 inches

Steel or material that provides a watertight seal.


4 - 12 inches

Asphalt and composite shingles.


5 - 12 inches

Wood shake or slate shingles.

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Roofing Basics FAQs

What type of roof do I have?

How can I find the age of my roof on my house?

What are the most popular roofing materials?

What are the main components of a roof?

What do I need to know about roofing?

Check This Guide Before Starting a Roofing Project

Understanding the roofing basics gives you a solid foundation. It lets you know how to spot issues with your current system, helps you understand what options are available for your roof’s pitch and gives you a better overall understanding of your home. And when it comes to your home, more knowledge is always better.

Ready to learn more about roofing? Check out the next post in our roofing series on how to budget for a new roof.

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