The Anatomy of a roof
1. Roof Decking (Sheathing)
This is the base of your roof, typically made from plywood or oriented strand board (OSB). The decking provides the structural foundation that supports all the roofing layers above.
2. Underlayment
Installed directly over the roof deck, the underlayment acts as a moisture barrier. There are two common types:
Felt paper (often called tar paper)
Synthetic underlayment, which offers better water resistance and tear strength
This layer provides added protection in case shingles are damaged or water seeps beneath them.
3. Ice and Water Shield
In colder climates or areas prone to ice dams, this waterproof membrane is added along eaves, valleys, and around penetrations like chimneys or vents. It helps prevent water from backing up under the shingles during freeze-thaw cycles.
4. Starter Shingles
These are the first row of shingles installed at the eaves and rakes. Starter shingles help create a secure seal and reduce the risk of wind uplift at the edges of the roof.
5. Asphalt Shingles
The visible outer layer, asphalt shingles are made from fiberglass or organic mats coated with asphalt and ceramic granules. They come in three main styles:
3-tab shingles: flat, uniform appearance
Architectural (dimensional) shingles: layered for a more textured, high-end look
Luxury shingles: thicker and designed to mimic slate or cedar shake
6. Flashing
Metal flashing is used around chimneys, skylights, vents, and roof valleys to direct water away from seams and joints. Common materials include aluminum, galvanized steel, or copper.
7. Ventilation System
Proper attic ventilation is crucial for the health of your roof. It includes:
Ridge vents
Soffit vents
Box or turbine vents
Good ventilation regulates attic temperature, prevents moisture buildup, and extends the lifespan of your roofing materials.
8. Ridge Cap Shingles
Installed along the roof’s ridge (the peak), these shingles seal the roof’s highest point and provide a finished look. They’re specially designed to resist wind and water infiltration.
Why It Matters
Each component plays a critical role in protecting your home from the elements. When one part fails—whether it’s missing shingles or poor ventilation—the entire system can suffer. That’s why professional installation and regular inspections are key to a long-lasting roof.
Need a Roof Checkup?
Whether you're planning a new installation or just want to understand your current system better, our experts are here to help. Contact us today to schedule an inspection or get a free quote!
