<h1>FOAMULAR R-1 Fanfold XPS Underlayment, 1/4 in. x 4 ft. x 50 ft</h1> <p><strong>High-performance XPS fanfold underlayment designed for re-siding and wall sheathing. Moisture-resistant and easy to cut, it delivers R-1 thermal performance in a flexible, square-edge format ideal for smooth, energy-efficient cladding prep.</strong></p> <h2>Key Features:</h2> <ul> <li><strong>Moisture Resistance:</strong> XPS construction retains R-value even in wet conditions</li><li><strong>Easy Handling:</strong> Lightweight panels score, cut, and install without special tools</li><li><strong>Flexible Fanfold Design:</strong> 50 ft. continuous coverage speeds re-siding prep</li><li><strong>Square Edge Fit:</strong> Flush seams for smooth sheathing under new siding</li><li><strong>Environmental Certifications:</strong> GREENGUARD Gold; listed in ENERGY STAR Seals and Insulates</li> </ul> <p><strong>Please check the Product Data Sheet <span>Here</span></strong></p> <h2>Specifications Table:</h2> <table> <tr> <th><strong>Specification</strong></th> <th><strong>Details</strong></th> </tr> <tr><td><strong>Insulation Type</strong></td><td>Foam Board Insulation (XPS)</td></tr><tr><td><strong>Insulation R-Value</strong></td><td>R-1</td></tr><tr><td><strong>Compressive Strength</strong></td><td>25 psi</td></tr><tr><td><strong>Thickness</strong></td><td>0.25 in (1/4 in.)</td></tr><tr><td><strong>Width</strong></td><td>48 in</td></tr><tr><td><strong>Length</strong></td><td>50 ft</td></tr><tr><td><strong>Coverage Area</strong></td><td>200 sq ft</td></tr><tr><td><strong>Edge Profile</strong></td><td>Square Edge</td></tr><tr><td><strong>Faced or Unfaced</strong></td><td>Unfaced</td></tr><tr><td><strong>Interior/Exterior Use</strong></td><td>Interior (re-siding sheathing)</td></tr><tr><td><strong>Insulation Location</strong></td><td>Re-Siding</td></tr><tr><td><strong>Compatible Install Surface</strong></td><td>Concrete, Plywood, Wood</td></tr><tr><td><strong>Number of Pieces</strong></td><td>1</td></tr><tr><td><strong>Pack Size</strong></td><td>1</td></tr><tr><td><strong>Product Weight</strong></td><td>13.2 lb</td></tr><tr><td><strong>Sheathing Type</strong></td><td>XPS</td></tr><tr><td><strong>Warranty</strong></td><td>Limited Lifetime</td></tr><tr><td><strong>Certifications</strong></td><td>GREENGUARD Gold; ENERGY STAR Seals and Insulates listing</td></tr><tr><td><strong>Environmental Note</strong></td><td>Manufactured with a blowing agent with >80% reduction in global warming potential vs. legacy FOAMULAR XPS</td></tr> </table> <h2>Frequently Asked Questions (FAQ):</h2> <p><strong>Q: Can this be used under new siding?</strong><br/> <strong>A:</strong> Yes, its designed as a re-siding fanfold underlayment to create a smooth, insulated surface.</p> <p><strong>Q: Is it suitable for damp areas?</strong><br/> <strong>A:</strong> The XPS foam resists moisture and maintains its R-value after exposure to water.</p> <p><strong>Q: Do I need special tools to install it?</strong><br/> <strong>A:</strong> No. Panels are easy to score and cut with common utility knives and install with standard fasteners or foamboard adhesive.</p> <p><strong>Q: What are the dimensions and coverage?</strong><br/> <strong>A:</strong> Thickness 1/4 in., width 48 in., length 50 ft; covers approximately 200 sq. ft.</p> <p><strong>Q: Is it soundproof?</strong><br/> <strong>A:</strong> No, this product is not rated for STC and does not provide soundproofing.</p> <h2>Streamlined Sheathing for a Flawless Facade</h2> <p>FOAMULARs fanfold underlayment creates an impeccably smooth canvas beneath fresh siding, elevating curb appeal while quietly boosting energy performance. The flexible, square-edge design glides over exterior walls for clean lines and a refined finish. Pair it with crisp fiber-cement or modern vinyl profiles to achieve a tailored, contemporary look. Its a smart, luxurious layer that makes exteriors feel deliberate and beautifully composed.</p> <p><strong>Upgrade your re-siding project with FOAMULAR fanfold underlayment for smoother walls and lasting energy savingsadd to cart today.</strong></p> <p>Installation</p>