Anatomy of A Roof

Would you like to know more about your roof's anatomy before having your roof replaced or repaired?

Uncover the different layers of your roof with our easy-to-use guide below.

Roof deck

In most cases, the roof deck is made of plywood and serves as the structural foundation for the roof system.

Ice and Water Underlayment

Ice and water underlayment is installed where rain or melting snow can cause an issue at the eaves, valleys, chimneys, skylights, and venting. It's a peel-and-stick underlayment that adheres to the roof deck.

Products to use: Resisto Lastobond HT-N or Resisto LB1236

Synthetic roofing Underlayment

There are various styles of roofing underlayment for a number of applications. Synthetic roofing underlayment is utilized over the roof deck and under the roofing material. It’s a nail-down underlayment that adds a layer of protection between the roofing material and the roof deck.

Products to use: Resisto Resistor Plus or Resisto Resistor


The eave is the lower edge of a roof that overhangs the wall, usually found in the first three feet.

Trims to use: Eaves Trim


Roof gables are the triangular sections of the exterior wall between a sloping roof and eaves. A gable can also be referred to as a rake.

Trims to use: Rake Edge

Drip Edge/Eave Trim/Rake Edge

Aluminum drip edges are installed along the eaves and gable ends of roofs. It helps prevent water from running behind the fascia board, causing damage such as rotting. 


On a roof, a hip is formed when two roof planes intersect to form a sloping ridge line.

Trims to use: Ridge/Hip Cap


A valley is when two sloped roofs intersect and create a "v" formation. 

Trims to use: Valley Flashing


The sidewall is where the side of a sloped roof meets with an exterior wall.

Trims to use: Sidewall Flashing


Endwall is where the exterior wall meets with the peak of a sloped roof.

Trims to use: Endwall Flashing

Ridge Vent

Ridge venting runs underneath the ridge cap to properly ventilate the attic space. It is possible to include ridge vents in the ridge cap or to purchase them as foam strips or rolls.

Products to use: Quarrix Ridge Vent or Foam Strip Venting

Ridge Cap

The ridge cap is a roofing material that covers the ridge and hip of the roof to prevent water and other weather elements from entering the home. 

Trims to use: Ridge/Hip Cap

Talk with your roofing contractor like a pro with this quick anatomy guide to your roof. Do you want to learn more about roofing keywords? Read our blog "Roofing Terms Every Homeowner Should Know."