When installing a new roof, each layer plays a critical role in ensuring the roof’s overall durability and protection. The first layer is one of the most important because it sets the foundation for the entire roofing system. So, what is the first layer added when roofing?
The Roof Deck: The Base Layer
While technically not part of the roofing material, the roof deck is the foundation upon which all other layers are added. It consists of plywood or oriented strand board (OSB) sheets that form the structural base of the roof. If you’re replacing an old roof, this decking is inspected and repaired before moving forward with any new materials.
The Drip Edge: Starting at the Edges
The drip edge is the first actual material installed as part of the roofing system. The drip edge is a metal flashing that goes along the edges of the roof, primarily at the eaves and rakes. Its main purpose is to direct water away from the fascia and into the gutter system, preventing water damage to the underlying materials.
The Underlayment: The First Protective Layer
The underlayment is the first significant layer added after the roof decking and drip edge. This layer is crucial because it serves as a protective barrier between the roof deck and the outer shingles, tiles, or metal roofing materials.
The underlayment is usually made from one of the following materials:
Felt Paper (Tar Paper): Traditionally used, felt paper is made from a mixture of asphalt and natural fibers, creating a waterproof barrier.
Synthetic Underlayment: In recent years, synthetic underlayment has become a more popular option due to its strength, durability, and resistance to moisture and tearing. It’s lighter and easier to install than felt paper.
Why is the Underlayment Important?
The underlayment is essential for several reasons:
Moisture Protection: It prevents water from penetrating the roof deck in case shingles are damaged or missing.
Weather Barrier: The underlayment provides a second layer of defense against wind-driven rain, ice, and snow, helping to keep the home dry.
Prolonging Roof Life: By adding a layer of protection between the shingles and the roof deck, the underlayment helps to prevent long-term damage, ensuring a longer-lasting roof.
How is the Underlayment Installed?
Once the roof deck is secured and inspected, the underlayment is rolled out and secured across the entire roof surface. It starts at the lowest point and works upward, with overlaps to ensure full coverage. This method creates a continuous barrier that prevents water from seeping in.
The Bottom Line
The first protective layer added when roofing is the underlayment, which plays a critical role in ensuring your roof stays watertight and resistant to the elements. Along with the drip edge, this layer provides the necessary foundation for the shingles or other roofing materials that follow. By installing the right underlayment, you ensure a strong, resilient roof that can stand up to weather conditions and protect your home for years to come.
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