The Anatomy of a Roof: What Every Homeowner Should Know

Your roof is more than what you see from the curb. It’s a layered, engineered system that protects your home from the elements.

1. Decking

The base layer. Typically made from plywood or OSB. This is the foundation everything else is attached to.

2. Underlayment

A water-resistant barrier placed between decking and shingles. It’s your last line of defense against leaks.

3. Ice & Water Shield

Installed in vulnerable areas like valleys and edges to prevent water intrusion from ice dams or wind-driven rain.

4. Shingles or Roofing Surface

The visible outer shell. Could be asphalt, metal, tile, or slate. Each has pros and cons.

5. Flashing

Thin metal installed around roof penetrations (chimneys, vents, skylights). Without flashing, these areas are prone to leaks.

6. Ventilation

Includes ridge vents, soffits, and gable vents. Proper airflow is essential to prevent moisture buildup and regulate temperature.

7. Gutters & Drainage

Not part of the roof per se, but critical to protect your foundation from runoff.

Understanding how your roof functions makes you a better-informed homeowner—and helps you catch small problems before they become big repairs.