In the roofing industry, misconceptions can spread quickly, and one of the most misleading is the claim that underlayment alone constitutes a roofing system. This misunderstanding has led to confusion among homeowners and even some professionals.
Underlayment is a critical component of any roofing system, regardless of location. However, it is not designed to be a standalone solution. Whether you live in Yakima, Washington, or anywhere else, a complete roofing system is essential for long-term protection and durability. Let’s break down what underlayment does, how it fits into the broader roofing system, and why relying solely on underlayment is a recipe for disaster.
What Is Roofing Underlayment?
Roofing underlayment is a layer of material installed beneath the roof covering (shingles, tiles, or metal panels) and above the roof deck. Its primary purpose is to provide an additional barrier against water infiltration, especially during construction or if the outer layer is damaged.
Underlayment serves as temporary protection during the roofing process and acts as a secondary defense once the roofingDebunking the Myth: Why Underlayment Isn’t a Roofing System
In the roofing industry, misconceptions can spread quickly, and one of the most misleading is the claim that underlayment alone constitutes a roofing system. This misunderstanding has led to confusion among homeowners and even some professionals.
Underlayment is a critical component of any roofing system, regardless of location. However, it is not designed to be a standalone solution. Whether you live in Yakima, Washington, or anywhere else, a complete roofing system is essential for long-term protection and durability. Let’s break down what underlayment does, how it fits into the broader roofing system, and why relying solely on underlayment is a recipe for disaster.
What Is Roofing Underlayment?
Roofing underlayment is a layer of material installed beneath the roof covering (shingles, tiles, or metal panels) and above the roof deck. Its primary purpose is to provide an additional barrier against water infiltration, especially during construction or if the outer layer is damaged.
Underlayment serves as temporary protection during the roofing process and acts as a secondary defense once the roofing system is complete. However, it cannot replace the outer roof covering, which shields the underlayment from the elements.
Common Types of Underlayment:
Asphalt-Saturated Felt: Traditional, cost-effective, but less durable and prone to degradation in extreme conditions.
Synthetic Underlayment: Lightweight, tear-resistant, and better suited for variable climates.
Rubberized Asphalt Underlayment: Premium waterproofing for areas prone to ice dams or heavy rain.
Why Underlayment Isn’t the Whole System
Underlayment is not a substitute for a complete roofing system, and here’s why:
1. Lacks Durability and Longevity
Underlayment is not designed to withstand prolonged exposure to the elements. Sunlight, rain, wind, and snow can quickly degrade it if left uncovered.
Without a protective top layer like shingles or tiles, the underlayment’s lifespan is significantly shortened.
2. Provides Limited Protection
Underlayment helps prevent water infiltration but cannot handle the full burden of protecting a home. The outer roof covering—shingles, tiles, shakes, or metal—is the primary defense against weather.
Roofing nails used to attach shingles penetrate the underlayment, creating potential pathways for water to seep through if it gets under the shingles. This is why the outer roof covering is essential to ensure water doesn’t reach the roof deck.
3. Doesn’t Meet Manufacturer or Building Standards
Most roofing material manufacturers specify underlayment as part of a system, not a standalone solution.
Building codes universally require complete roofing systems, including ventilation, flashing, and durable top layers.
The Temporary Role of Underlayment During Roofing or Re-Roofing
Underlayment plays a critical role during the roofing process, ensuring that the home remains protected while the roof is being installed or replaced.
How Underlayment Protects During Construction:
Quick Dry-In for Interior Work:
Underlayment shields the roof deck from weather, allowing contractors like electricians, drywallers, and painters to continue their work without delays caused by leaks or exposure.
Protection During Re-Roofing:
When replacing an existing roof, underlayment prevents moisture damage to the exposed roof deck until the new roof covering is installed.
Temporary Yet Essential:
While underlayment provides short-term protection, it is not designed to be exposed indefinitely. Completing the roofing process promptly ensures the integrity of the underlayment and the entire system.
Lessons from Other Regions: A Cautionary Tale
In some areas, such as Las Vegas, roofing practices differ significantly. For example, it is common on tile roofs not to install pipe flashings, allowing water to run underneath the tiles and rely solely on the underlayment. While this might work temporarily in dry climates, it can lead to long-term issues.
We’ve seen firsthand how this approach can backfire. A homeowner in Las Vegas contacted us after receiving a bid from a local contractor to tear off her tiles, install new underlayment and battens, and reinstall the old tiles. However, this plan would not have addressed the root problem—the lack of proper flashing and drainage—and would have left her with the same issues. Instead, a complete roofing system addressing all components, including flashing, was necessary to prevent future water infiltration.
The lesson here is clear: underlayment alone, even with new materials, is not sufficient to resolve systemic roofing issues. Comprehensive solutions are critical for long-term durability.
The True Definition of a Roofing System
A complete roofing system is a combination of multiple components working together to protect a home. These components include:
Roof Deck: The structural foundation of the roof, typically made of plywood or OSB.
Underlayment: Provides a secondary barrier against water infiltration.
Roof Covering: The visible top layer, such as asphalt shingles, tiles, or metal panels, which serves as the primary defense against weather.
Flashing: Metal pieces that seal edges and joints, preventing water entry at vulnerable points like chimneys and vents.
Ventilation: Ensures proper airflow to prevent moisture buildup and extend the life of the roof.
Underlayment: A Universal Need
The misconception that underlayment can function as the sole roofing system often arises in areas with mild climates. However, even in regions with limited rainfall or temperature extremes, underlayment is not designed to withstand prolonged exposure. Without the protection of shingles, tiles, or metal panels, it will deteriorate rapidly, leaving the home vulnerable to leaks and damage.
Whether in Yakima, Washington, or any other location, a complete roofing system is essential to ensure long-term durability and weather resistance. Every component of the roof has a specific role, and underlayment alone cannot meet the demands of protecting a home.
The Right Way to Approach Roofing
For homeowners everywhere, a complete roofing system is the only reliable way to ensure long-term protection and durability.
What to Demand from Your Roofing Contractor:
Proper Installation: Ensure they follow manufacturer guidelines and include all components of a roofing system.
High-Quality Materials: Select underlayment and roof coverings that can withstand local weather conditions.
Regular Inspections: Seasonal weather changes can take a toll on your roof, so schedule inspections to catch issues early.
Conclusion: Don’t Fall for Half-Truths
Underlayment is an essential component of any roofing system, but it’s not the roof itself. Misleading claims can leave homeowners vulnerable to premature roof failures and costly repairs. A complete roofing system—including the roof deck, underlayment, shingles or tiles, flashing, and ventilation—is necessary to ensure long-term protection and durability.
No matter where you live, cutting corners on your roofing system isn’t an option. Choose a contractor who values quality, transparency, and the importance of a full roofing system. Protect your home with a roof built to last.