Understanding Roof Layers and Their Functions
A durable roof is a layered system. Decking (OSB/plywood) spans framing and takes fasteners. Underlayment provides a secondary water-shedding surface; laps and perm rating must match slope and climate. Ice-and-water shield protects eaves, valleys, and penetrations, installed on clean, dry substrates. Metal flashing and compatible sealants manage joints and movement. Ventilation balances soffit intake with …
