Choosing the right roofing underlayment is crucial for ensuring the longevity and durability of your roof. Two common types of underlayment are synthetic and felt (also known as asphalt-saturated felt or tar paper). While both have been widely used in the roofing industry, the growing popularity of synthetic options raises the question: Which is better? In this article, we’ll compare synthetic roofing underlayment and felt to help you make an informed decision.

**1. Durability and Longevity**  

**Synthetic Underlayment**: Synthetic roofing underlayment is made from durable polymers, providing excellent resistance to tearing, UV exposure, and moisture. It has a longer lifespan compared to felt, often lasting as long as the roof itself.

**Felt Underlayment**: Felt is made from natural materials, typically cellulose, wood fibers, and asphalt. While it has been a reliable option for many years, felt is more prone to tearing, especially when wet, and can deteriorate faster than synthetic underlayment.

**Winner**: **Synthetic** - It offers superior durability and longevity, making it a more reliable choice for long-term roof protection.

**2. Water Resistance**  

**Synthetic Underlayment**: Synthetic materials are highly water-resistant and do not absorb moisture, which helps prevent water from seeping into the roof deck and causing damage.

**Felt Underlayment**: Felt can absorb water, which can lead to wrinkling and degradation over time. Although felt provides a level of water resistance, it is not as effective as synthetic underlayment in preventing water infiltration.

**Winner**: **Synthetic** - Its excellent water resistance ensures better protection against moisture-related issues.

**3. Weight and Installation**  

**Synthetic Underlayment**: Synthetic underlayment is lightweight, making it easier to handle and install. This reduces the labor time and cost associated with installation. It also typically comes in larger rolls, covering more area per roll than felt.

**Felt Underlayment**: Felt is heavier and more cumbersome to work with, which can make installation more time-consuming and labor-intensive. Additionally, felt is often more difficult to install in colder temperatures as it can become brittle.

**Winner**: **Synthetic** - The lighter weight and ease of installation make it a more convenient option for roofers.

**4. UV Resistance**  

**Synthetic Underlayment**: Synthetic underlayment can withstand extended exposure to UV rays without breaking down, allowing it to be left exposed for longer periods before the final roofing material is installed.

**Felt Underlayment**: Felt degrades quickly when exposed to UV light, which means it needs to be covered with the final roofing material relatively quickly to avoid damage.

**Winner**: **Synthetic** - Better UV resistance offers more flexibility during the roofing process.

**5. Cost**  

**Synthetic Underlayment**: While synthetic underlayment is generally more expensive than felt, its superior performance and longer lifespan can result in better long-term value.

**Felt Underlayment**: Felt is less expensive upfront, making it a cost-effective option for budget-conscious projects. However, its shorter lifespan and higher maintenance requirements may increase overall costs in the long run.

**Winner**: **It Depends** - Felt may be the better choice for those prioritizing initial cost, but synthetic underlayment offers better long-term value.

When comparing synthetic roofing underlayment to felt, synthetic options clearly outperform felt in terms of durability, water resistance, weight, and UV resistance. While felt may have a lower upfront cost, synthetic underlayment’s long-term benefits make it the superior choice for those looking to invest in a durable and reliable roofing solution.

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