Synthetic vs. Felt Roofing Underlayment: Which Is Better?

• Josh Hunter
• 3 months ago
• Categories: Roofing
• Tags: felt, roof underlayment, synthetic, underlayment

Roofing contractors know all too well the importance of the underlayment. Installed right on top of the decking before the shingles are laid down, it plays a crucial role in protecting the entire structure from water intrusion.

When it comes to this critical roofing component, two materials often come to mind: felt and synthetic. Roofmasters Roofing and Sheet Metal Company takes a look at the differences of these popular underlayment types.

Understanding Felt Roofing Underlayment

Felt underlayment, often referred to as tar paper or felt paper, has been a staple in the roofing industry for decades. It is made by saturating paper or fiberglass mat with asphalt. Felt underlayment comes mainly in two thicknesses: 15-pound and 30-pound, with the latter offering more durability and better protection. Its popularity is rooted in tradition and its relatively low cost.

Pros of Felt Underlayment

• More affordable than synthetic options
• Generally acceptable for most residential roofing applications
• Familiarity and comfort amongst roofing companies with its installation

Cons of Felt Underlayment

• Heavier and more difficult to work with, especially in windy conditions
• Absorbs moisture and can wrinkle when exposed to weather, which may affect the shingle installation
• Less durable over time; it can tear easier underfoot and degrade with exposure to UV light

The Rise of Synthetic Roofing Underlayment

Synthetic underlayment is a newer innovation in the roofing industry, manufactured from woven or spun polyethylene or polypropylene. They are designed to be stronger, lighter, and more resistant to weather elements than felt underlayment.

Pros of Synthetic Underlayment

• Extremely lightweight and strong, offering better durability than felt.
• Often designed with walkability in mind, providing safer surfaces for workers.
• Resists moisture and does not absorb water, reducing the likelihood of mold and rot.
• Can withstand UV exposure for a longer period if left uncovered.

Cons of Synthetic Underlayment

• More expensive upfront than felt underlayment
• Installation may require more particular roofing staples or cap nails, translating into additional cost and labor

Which One Should You Choose?

Both the synthetic and felt underlayment have their places within the roofing industry. Synthetic is mostly the go-to choice for many roofers when it comes to roof installations nowadays, but don’t discount the benefits of felt. After all, it is a material that installers from long ago use.

During instances where you are presented with choices when it comes to roof components, it’s always advisable to consult with local professionals like Roofmasters Roofing and Sheet Metal Company. Our team is committed to providing suitable solutions for your roofing needs. Call us today at (785) 628-3614, or fill out our contact form to request an estimate. We serve homeowners in Colby and Hays, KS.