What Goes on Roof Before Shingles

What Goes on Roof Before Shingles: Essential Layers and Materials Explained

Installing shingles is the final step in roofing, but several vital layers and materials must be applied before shingles to ensure a durable, weatherproof roof. These layers not only protect the home from moisture, wind, and temperature extremes but also enhance the lifespan and performance of the shingles themselves. Understanding what goes on a roof before shingles is crucial for homeowners, contractors, and DIY enthusiasts seeking a reliable roofing system.

Roof Deck: The Structural Foundation

The roof deck is the primary surface on which the roofing system is built. Typically constructed of plywood or oriented strand board (OSB), it provides a stable base for all subsequent layers. The deck must be securely fastened to the roof’s framing, thoroughly inspected for damage or rot, and repaired or replaced as necessary before adding any underlayers. A strong, smooth roof deck ensures shingles lay flat and last longer.

Ice and Water Shield: Critical Waterproofing for Vulnerable Areas

Ice and water shield membranes are essential in climates prone to ice dams or heavy rain. This self-adhering, rubberized asphalt membrane is applied along roof edges, eaves, valleys, and around penetrations like chimneys or vents. It acts as a waterproof barrier, preventing water from seeping beneath shingles or into the roof structure. Installing this layer before shingles significantly reduces the risk of leaks and water damage.

Roof Underlayment: Secondary Protection

Underlayment serves as the second line of defense against moisture infiltration. This layer covers the entire roof deck, creating a smooth, continuous surface for shingles to adhere to. Several types of underlayment exist:

• Felt Paper: Traditional roofing felt made of asphalt-saturated fibers.
• Synthetic Underlayment: Lightweight, tear-resistant, and more durable alternative to felt.

The choice of underlayment depends on budget considerations, climate, and roofing specifications. Proper install ensures improved waterproofing, and protects the deck from wind-driven rain.

Drip Edge: Protecting Roof Edges

Drip edges are metal strips installed around the roof perimeter. Positioned beneath shingles but over the underlayment, they guide water away from the fascia and prevent capillary action that can cause wood rot. Drip edges also help direct rainwater into gutters efficiently. Aluminum and galvanized steel are common materials due to corrosion resistance and durability.

Flashing: Sealing Roof Penetrations

Flashing is critical to waterproofing areas where the roof surface is penetrated or joined. This includes around chimneys, skylights, vents, and valleys. Metal flashing, usually aluminum, copper, or galvanized steel, is shaped to direct water away from vulnerabilities. Properly installed flashing prevents leaks, mold, and internal structural damage.

Additional Components Before Shingles

• Starter Strip Shingles: Installed at the roof edges before full shingles, they create a secure foundation that enhances shingle adhesion and wind resistance.
• Roof Vents: Ventilation components like ridge vents or soffit vents may be installed before shingles to promote airflow, reduce heat buildup, and prevent moisture accumulation.

Summary of What Goes On Roof Before Shingles