Roofing felt is typically 15 to 30 pounds thick, though thickness varies by type and purpose. The “pound” rating refers to how much one roll weighs per 100 square feet. Most homeowners use either 15-pound or 30-pound felt as an underlayment under shingles. Thicker felt costs more but lasts longer and protects better. According to industry data, roofing felt serves as a critical moisture barrier between your deck and shingles. Understanding felt thickness helps you pick the right product for your roof’s needs.
What Are the Main Thickness Types?
Roofing felt comes in two main weights: 15-pound and 30-pound. The 15-pound felt is lighter and cheaper, making it popular for basic projects. The 30-pound felt is heavier, more durable, and offers better protection against weather.
Most roofers choose 30-pound felt for its strength. It resists tearing during installation and holds up better over time. Thicker felt also provides better cushioning for your shingles.
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Why Does Thickness Matter for Your Roof?
Thicker felt protects your roof from water damage and extends shingle life. According to RubyHome, asphalt shingles typically last 20 to 30 years when installed correctly with good underlayment. Thicker felt helps achieve that lifespan.
Poor underlayment can lead to leaks and costly repairs. A quality felt layer stops moisture from reaching your roof deck. This prevents rot, mold, and structural damage.
Roofing Felt Weight Comparison
| Felt Type | Weight | Cost | Lifespan |
|---|---|---|---|
| 15-Pound Felt | Light | Lower | 15-20 years |
| 30-Pound Felt | Heavy | Higher | 25-30 years |
| Synthetic Felt | Variable | Premium | 30+ years |
What About Modern Felt Alternatives?
Synthetic felt is newer and often better than traditional asphalt felt. It resists tearing, lasts longer, and handles moisture better. According to IBISWorld, cool roofs and advanced roofing systems are gaining major market share as homeowners seek durability and energy efficiency.
Synthetic felt costs more upfront but saves money long term. It won’t rot or break down as fast as asphalt-based felt. Many roofers now recommend synthetic underlayment for quality jobs.