Why Roof Underlayment Is a Crucial Part of Any System

The Layer That Protects What You Can’t See

When most homeowners in Santa Monica, CA think about roofing, they imagine shingles, tiles, or metal panels. But what lies underneath is just as important—if not more. Roof underlayment is the hidden yet vital component that serves as your home's last line of defense against leaks, moisture, and wind-driven rain. At Economy Roofing, we emphasize the importance of choosing the right underlayment as part of a durable, high-performing roofing system.

Whether you’re installing a new roof or replacing an old one, understanding the role of underlayment can help protect your home for decades to come.

What Is Roof Underlayment?

A Protective Barrier Beneath the Surface

Roof underlayment is the water-resistant or waterproof layer that sits between your roof deck and the outer roofing material. It serves several critical functions, including:

• Providing backup protection if shingles or tiles are damaged

• Preventing water intrusion during heavy rain or snow

• Acting as a moisture barrier during installation

There are three primary types of underlayment:

1. Asphalt-saturated felt

2. Synthetic underlayment

3. Rubberized asphalt (for high-performance applications)

Each option has unique benefits, and the best choice depends on your roof design, climate, and budget.

Why Underlayment Matters

Added Protection Against Leaks

Even the most durable shingles or tiles can fail under extreme conditions. High winds may lift shingles, exposing nail penetrations and allowing water to seep through. Underlayment offers a second layer of defense, preventing leaks from reaching your interior.

This is especially critical in coastal regions like Santa Monica, where fog, salt, and wind can all contribute to roof wear.

Moisture Control and Ventilation Support

Underlayment also plays a role in moisture control inside your attic. When used alongside proper attic ventilation systems, it helps prevent condensation, mold, and wood rot. High-quality brands like Owens Corning and Malarkey design their roofing products to work in tandem—underlayment included—for total system protection.

Underlayment and Warranty Compliance

Don’t Risk Losing Coverage

Most roofing material warranties require specific types of underlayment for full coverage. Installing the wrong product—or skipping it entirely—can void manufacturer warranties and leave homeowners financially responsible for future repairs.

At Economy Roofing, we ensure your roof installation complies with brand standards and local building codes, offering peace of mind with every layer we install.

Choosing the Right Underlayment

Factors to Consider

When selecting underlayment, your roofing contractor should assess:

• Roof slope

• Material compatibility (e.g., metal vs. asphalt)

• Local weather conditions

• Budget and warranty requirements

For example, synthetic underlayments are more tear-resistant and longer-lasting than traditional felt. Meanwhile, rubberized asphalt offers excellent waterproofing for low-slope or vulnerable areas like valleys and roof edges.

We recommend pairing underlayment with complete system components from brands such as Malarkey or Owens Corning for optimal performance and long-term protection.

Installation Matters as Much as Material

Hire the Right Team

Even the best underlayment won’t protect your home if installed incorrectly. Seams must be overlapped properly, nails must be spaced and sealed, and flashing must be integrated into the system. Poor workmanship can lead to early failure—even with premium materials.

That’s why choosing a reputable contractor with proven experience is essential. In Santa Monica, CA, Economy Roofing ensures every layer is installed with precision, from the deck to the top shingle.

Read also our blog: The Benefits of Choosing Slate Roofing Systems