Roofing underlayment is essential for any new roof installation or re-roofing job. These materials provide a barrier against moisture, adding an extra layer of protection. They are typically laid over the roof deck, which is usually made of OSB or plywood, with the roofing material placed on top. Given the unique features of metal roofs, it’s important to consider these when selecting an underlayment. Continue reading to find out which underlayment is best suited for your metal roof.
Considerations for Metal Roofing Underlayment
Roofing underlayments are crucial for metal roofs, just as they are for asphalt, tile, or slate roofs. They act as a secondary barrier against water from heavy rains, melting snow, and ice dams in colder climates. Metal roofs can generate significant heat, so the underlayment must be suitable for high temperatures and comply with the roofing manufacturer’s guidelines. When choosing an underlayment for your metal roof, consider its moisture barrier capabilities, your regional and climatic location, local building codes, commonly used products by local contractors, and your roof’s slope.
Underlayment Options for Roofing
Metal roof underlayments are classified by their application and installation techniques, such as:
- Self-Adhered (also known as Ice and Water Barrier)
- Synthetic
Why Avoid Felt?
Synthetic underlayments surpass felt in every aspect, regardless of roofing material like asphalt, tile, or metal. While felt has been used for many years, synthetics are now preferred for their superior durability and performance. Felt underlayments tend to:
- Tear easily
- Absorb water
- Be heavier than synthetics
- Wrinkle
- Offer less traction than synthetics
Self-adhered underlayments
Self-adhered roofing underlayments are an excellent option for homeowners seeking enhanced protection under their metal roofs. The adhesive backing forms a tight bond with the roof deck, ensuring a waterproof seal and protection against ice dams, particularly in areas like eaves, valleys, and dormers. These underlayments can be applied over the entire roof deck or just in vulnerable spots.
With their flexible installation, non-skid surfaces, and strong adhesion, self-adhered underlayments are a popular choice for both homeowners and roofing contractors.
Owens Corning provides a variety of self-adhered underlayments ideal for metal roofs. These products create an additional moisture barrier, supporting the integrity of your roofing system:
- WeatherLock® Specialty Tile & Metal
- Titanium® PSU30
- Titanium® FR
Synthetic Roof Underlayments
Synthetic roof underlayments are made from durable synthetic fibers woven into a strong, high-tear-strength material. This design helps prevent moisture infiltration, while their water-repellent surface minimizes mold risks by quickly draining away water.
These underlayments are often coated with a non-slip surface to improve worker safety during installation and feature printed markings for accurate fastener placement. They offer superior performance for metal roofing compared to traditional felt products.
Key advantages include:
- Greater Strength: Resists tears and handles foot traffic better than felt.
- Extended UV Resistance: Some products can withstand UV exposure for up to 180 days without degradation.
- Lightweight: Much lighter than No. 30 felt.
- Larger Roll Sizes: Reduces the need for frequent ladder trips due to wider and longer rolls.
Owens Corning offers various synthetic underlayments for metal roofs, each with features tailored to specific needs:
- ProArmor®
- DeckDefense®
- RhinoRoof® U20
- Titanium® UDL25, UDL30, and UDL50
- Titanium® X30
Owens Corning Underlayment Choices for Metal Roofing Projects
To ensure your metal roof system lasts for years to come, it’s important to protect your roof deck from eave to peak. Explore Owens Corning’s underlayment options for metal roofing and learn about the unique benefits of each product.
Self-Adhering Underlayments (Ice and Water Protection Solutions)
Owens Corning WeatherLock® Specialty Tile & Metal
This self-adhered underlayment offers effective water protection by sealing around fasteners and roof penetrations. Its single-layer polyester fabric is designed to handle the high temperatures produced by metal roofs.
- UV Resistance: Up to 180 days
- Traction: Slip-resistant non-woven polyester
- Temperature Tolerance: Suitable for metal roofing systems
- Warranty: 30-year Limited†
Titanium® PSU30
This versatile water barrier provides robust protection for your roof deck against both ice dams in winter and high summer temperatures. Made from modified rubberized asphalt with a synthetic facer, this underlayment offers excellent durability and remains flat and secure under metal roofing. Titanium® PSU30 is known for its high walkability and strong deck adhesion, making it ideal for steep-sloped metal roofs.
- UV Resistance: Up to 180 days
- Traction: Sure-Foot® nodular walking surface
- Temperature Tolerance: High temperature rated for metal roofs
- Warranty: Limited Lifetime†
Titanium® FR
For homes located in Wildland Urban Interface (WUI) zones where stringent fire resistance codes apply, Titanium® FR underlayment helps your metal roof achieve a Class A Fire Rating. Its advanced technology is designed to minimize the spread of fire to the roof deck.
- UV Resistance: 180 days
- Traction: Sure-Foot® nodular walking surface
- Temperature Tolerance: High temperature rated for metal roofing systems
- Warranty: Limited Lifetime†
Synthetic Underlayments: Owens Corning ProArmor®
Owens Corning ProArmor® synthetic underlayment offers superior moisture protection for metal roofs compared to traditional felt. ProArmor® is up to 12 times stronger than felt‡‡ and covers up to 450% more area per roll than competing felt products. Its slip-resistant surface and minimal ladder trips make for a smooth installation process.
- UV Resistance: 90 days
- Traction: Fusion Back Coating Technology®
- Temperature Tolerance: High temperature rated for metal roofing systems
- Warranty: 10-year Limited†
Titanium® UDL25, UDL30, and UDL50
Titanium® UDL25, UDL30, and UDL50 are advanced synthetic underlayments designed as a superior alternative to felt for residential roofing. These underlayments are specifically suited for metal roofs and offer much greater tear resistance than felt, along with larger roll sizes and lighter weights for easier installation.
- UV Rays Resistance: 180 days
- Traction: Sure-Foot® nodular walking surface
- Temperature Tolerance: High temperature rated for metal roofing systems
- Warranty: Lifetime limited
Tear Strength Compared to No. 30 Felt:
- UDL25: 14 times stronger
- UDL30: 20 times stronger
- UDL50: 25 times stronger
Titanium® X30
For ultimate safety and ease of installation on any roof slope or condition, Titanium® X30 with Comfort Grip™ Technology is an excellent choice. This premium underlayment offers the same high performance as other Titanium products while providing enhanced cushioning and superior traction for safer and more comfortable walkability.
RhinoRoof® U20
RhinoRoof® U20 is known for its exceptional durability and wind resistance. This synthetic underlayment stands up to heavy foot traffic, resists sliding and tearing, and provides a secure, gripping surface for your roofing project.
- UV Rays Resistance: 90 days
- Traction: FiberGrip surface
- Temperature Tolerance: High temperature rated for metal roofing systems
- Warranty: 20-year limited
How to Choose the Best Metal Roofing Underlayment for Your Needs
Selecting the ideal metal roofing underlayment depends on your project’s requirements, budget, and local building codes. Manufacturers provide guidance on the suitability of their products for specific types of metal roofing, regional conditions, and roof slopes.
Synthetic Underlayment Testing Standards
A collaborative effort among manufacturers, contractors, and consultants has led to the creation of a testing standard for synthetic underlayments. The ASTM D8257 standard from the American Society for Testing and Materials outlines the criteria for evaluating these products, helping you compare options effectively.
Consult with a Professional Roofing Contractor
To determine the best underlayment for your project, it’s essential to seek advice from a skilled roofing contractor. The Owens Corning Roofing Contractor Network includes experienced professionals who have proven their expertise and reliability. You can find a qualified contractor near you by searching with your zip code.