Commercial Property
Inspection Service In Ocala, FL
Commercial Property
Inspection Service In Ocala, FL
In sloped asphalt shingle assemblies, the underlayment serves as the secondary water-shedding
barrier. While traditional asphalt-saturated felt has historically been standard, modern synthetic
underlayments provide measurable performance advantages.
1. Moisture Management
Asphalt-saturated felt is hygroscopic — it absorbs moisture, which can lead to wrinkling, dimensional
instability, and reduced surface smoothness beneath shingles. Synthetic underlayments are
non-absorptive and maintain dimensional stability under variable humidity conditions.
2. Tear Strength & Fastener Retention
Synthetic products exhibit significantly higher tensile strength and improved nail pull-through resistance
compared to #15 or #30 felt. This is particularly important during high-wind events, on steep slopes,
and during installation foot traffic. Once shingles are installed, underlayment cannot be inspected,
making material integrity at installation critical.
3. UV Resistance & Exposure Ratings
Felt degrades rapidly when exposed to sunlight. Most synthetic underlayments offer extended UV
exposure ratings, providing flexibility during weather or scheduling delays.
4. Installation Efficiency
Synthetic underlayments cover more square footage per roll, weigh less, and require fewer seams per
square. Fewer seams translate to fewer potential water intrusion pathways.
5. Risk Mitigation & Liability Reduction
From a risk management perspective, upgrading underlayment improves secondary barrier reliability,
reduces callbacks, enhances long-term roof assembly durability, and supports manufacturer system
warranties when applicable.
Conclusion
While felt remains code-compliant in many jurisdictions, synthetic underlayment represents a
performance-driven upgrade that improves tear resistance, moisture stability, and overall system
reliability on sloped roof applications.