When it comes to roofing, underlayment plays a crucial role in protecting the home from moisture, preventing leaks, and adding an extra layer of protection to the roofing system. It acts as a barrier between the roof deck and the roofing material (such as shingles), helping to shield the structure from water infiltration, wind damage, and other environmental factors. Different types of underlayment are available, and choosing the right one depends on several factors, including climate, building codes, budget, and the roofing material. Heres a detailed look at the most common roofing underlayment types and where each one works best.
1. Asphalt-Saturated Felt (Tar Paper)
Asphalt-saturated felt, often referred to as tar paper, is one of the most traditional and widely used roofing underlayments. It is made of a base material (such as fiberglass or organic felt) that is saturated with asphalt to create a waterproof barrier.
Pros of Asphalt-Saturated Felt:
Affordable: Asphalt-saturated felt is one of the least expensive roofing underlayment options, making it a popular choice for budget-conscious homeowners.
Time-Tested Performance: It has been used for decades in the roofing industry and has a proven track record of performance.
Water Resistance: Asphalt felt provides good water resistance and is effective at preventing water from seeping through the roofing system.
Cons of Asphalt-Saturated Felt:
Vulnerable to UV Damage: Asphalt-saturated felt can degrade over time when exposed to sunlight. Prolonged UV exposure can cause it to become brittle, reducing its effectiveness.
Heavy and Difficult to Install: It is heavier and more difficult to handle during installation compared to other modern underlayments.
Limited Durability: While effective, asphalt-saturated felt doesnt provide the same level of protection or longevity as synthetic options.
Best Use:
Asphalt-saturated felt works best in moderate climates where UV exposure is not as intense, and the roofing material is relatively easy to install. It is a good option for homeowners on a budget and those who live in areas where the roof does not face extreme weather conditions.
2. Synthetic Underlayment
Synthetic underlayment is a more modern alternative to asphalt-saturated felt. It is made of polymer materials such as polypropylene or polyester, which are designed to provide superior protection against water, wind, and UV rays.
Pros of Synthetic Underlayment:
Superior Durability: Synthetic underlayment is more durable than asphalt-saturated felt and can withstand prolonged exposure to the sun without degrading.
Lightweight: It is much lighter and easier to handle during installation compared to traditional felt.
Waterproof and Moisture Resistant: It provides excellent protection against water penetration and is less likely to tear or break down under wet conditions.
UV Resistance: Unlike asphalt felt, synthetic underlayment is UV-resistant and can remain exposed for weeks without deteriorating.
Cons of Synthetic Underlayment:
Higher Initial Cost: Synthetic underlayment tends to be more expensive than asphalt-saturated felt, although the durability and long-term protection can justify the extra cost.
Installation Challenges: While lighter, synthetic underlayment can be slippery, making it a bit more challenging to walk on during installation.
Best Use:
Synthetic underlayment is ideal for extreme climates, such as areas prone to heavy rain, snow, or intense sunlight. Its also a great choice for high-end roofing systems and for homeowners looking for long-term durability and enhanced performance. Contractors often recommend synthetic underlayment for steep-slope roofing and for installations in areas with harsh weather conditions, such as coastal regions or areas with extreme heat.
3. Rubberized Asphalt Underlayment
Rubberized asphalt underlayment is a modified form of traditional asphalt underlayment. It combines asphalt with rubber polymers, giving it a higher level of flexibility and waterproofing capabilities. This underlayment is typically self-adhesive, which makes installation easier and provides additional protection.
Pros of Rubberized Asphalt Underlayment:
Excellent Waterproofing: Rubberized asphalt underlayment is highly resistant to water infiltration, making it ideal for areas prone to heavy rainfall or where water protection is critical.
Self-Adhesive: The self-adhesive backing makes installation faster and helps create a tight seal around fasteners, reducing the risk of leaks.
Enhanced Durability: The rubber content improves the underlayments flexibility and resilience, allowing it to perform better in extreme temperatures.
Cons of Rubberized Asphalt Underlayment:
Cost: Rubberized asphalt underlayment tends to be more expensive than other options due to its enhanced features.
Limited Breathability: While its great for waterproofing, rubberized asphalt can sometimes trap moisture, which could lead to mold or mildew growth in certain applications.
Best Use:
Rubberized asphalt underlayment is most suitable for areas with heavy rainfall, snow, or ice. It is particularly useful for valleys, eaves, and other areas of the roof that are prone to leaks or ice dams. It is also ideal for low-slope roofs or roofing projects where waterproofing is a high priority.
4. Metal Roofing Underlayment
For metal roofing systems, a special underlayment is often required to handle the unique characteristics of metal roofing. Metal roofing underlayment is typically made from a combination of fiberglass or polyester, coated with a special membrane that provides moisture resistance and durability.
Pros of Metal Roofing Underlayment:
Heat Resistance: Metal roofing underlayment is designed to handle the high temperatures that can occur beneath metal roofs, which can get very hot in direct sunlight.
Moisture Protection: It provides excellent moisture protection and can resist water penetration, ensuring the roof deck remains dry.
Durable and Lightweight: It is generally lightweight, making it easy to handle during installation. Its also durable, ensuring a long-lasting roofing system.
Cons of Metal Roofing Underlayment:
Cost: Like synthetic underlayment, metal roofing underlayment can be more expensive than traditional asphalt felt.
Installation Complexity: Metal roofing underlayment can be more difficult to install and requires special attention to detail to ensure proper adhesion and alignment with the roofing panels.
Best Use:
Metal roofing underlayment is best for metal roofing systems, especially in areas with hot climates. Its a great choice for homeowners who want to install metal roofing, as it offers the necessary protection and durability required for these materials.
5. Felt vs. Synthetic: Which Is Better?
Felt Underlayment: Best for standard roofing applications where cost is a key factor and there are fewer concerns about extreme weather conditions or UV exposure.
Synthetic Underlayment: Ideal for high-performance, long-lasting roofs that need the ultimate in protection, especially in regions with severe weather or harsh UV exposure.
Conclusion
The best roofing underlayment for your project depends on factors like the climate, the roofing material, and your budget. Each type of underlaymentwhether its asphalt-saturated felt, synthetic, rubberized asphalt, or a specialty option like metal roofing underlaymenthas its unique advantages. Distributors should be well-versed in the pros and cons of each type to ensure they can recommend the best solution for contractors and homeowners alike. By understanding how different underlayment materials perform in different conditions, you can help ensure the longevity and durability of the roofing system, ultimately providing a higher level of protection and peace of mind for building owners.
