Owens Corning R-1 (25 PSI) FOAMULAR Extruded Polystyrene Fanfold Underlayment Insulation, 1/4 in. x 48 in. x 50 ft, Square Edge
FOAMULAR R-1 Fanfold XPS Underlayment, 1/4 in. x 4 ft. x 50 ft
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.
Key Features:
- Moisture Resistance: XPS construction retains R-value even in wet conditions
- Easy Handling: Lightweight panels score, cut, and install without special tools
- Flexible Fanfold Design: 50 ft. continuous coverage speeds re-siding prep
- Square Edge Fit: Flush seams for smooth sheathing under new siding
- Environmental Certifications: GREENGUARD Gold; listed in ENERGY STAR Seals and Insulates
Please check the Product Data Sheet Here
Specifications Table:
| Specification | Details |
|---|---|
| Insulation Type | Foam Board Insulation (XPS) |
| Insulation R-Value | R-1 |
| Compressive Strength | 25 psi |
| Thickness | 0.25 in (1/4 in.) |
| Width | 48 in |
| Length | 50 ft |
| Coverage Area | 200 sq ft |
| Edge Profile | Square Edge |
| Faced or Unfaced | Unfaced |
| Interior/Exterior Use | Interior (re-siding sheathing) |
| Insulation Location | Re-Siding |
| Compatible Install Surface | Concrete, Plywood, Wood |
| Number of Pieces | 1 |
| Pack Size | 1 |
| Product Weight | 13.2 lb |
| Sheathing Type | XPS |
| Warranty | Limited Lifetime |
| Certifications | GREENGUARD Gold; ENERGY STAR Seals and Insulates listing |
| Environmental Note | Manufactured with a blowing agent with >80% reduction in global warming potential vs. legacy FOAMULAR XPS |
Frequently Asked Questions (FAQ):
Q: Can this be used under new siding?
A: Yes, it’s designed as a re-siding fanfold underlayment to create a smooth, insulated surface.
Q: Is it suitable for damp areas?
A: The XPS foam resists moisture and maintains its R-value after exposure to water.
Q: Do I need special tools to install it?
A: No. Panels are easy to score and cut with common utility knives and install with standard fasteners or foamboard adhesive.
Q: What are the dimensions and coverage?
A: Thickness 1/4 in., width 48 in., length 50 ft; covers approximately 200 sq. ft.
Q: Is it soundproof?
A: No, this product is not rated for STC and does not provide soundproofing.
Streamlined Sheathing for a Flawless Facade
FOAMULAR’s 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. It’s a smart, luxurious layer that makes exteriors feel deliberate and beautifully composed.
Upgrade your re-siding project with FOAMULAR fanfold underlayment for smoother walls and lasting energy savings—add to cart today.
Original: $70.55
-70%$70.55
$21.16Product Information
Product Information
Shipping & Returns
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Description
FOAMULAR R-1 Fanfold XPS Underlayment, 1/4 in. x 4 ft. x 50 ft
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.
Key Features:
- Moisture Resistance: XPS construction retains R-value even in wet conditions
- Easy Handling: Lightweight panels score, cut, and install without special tools
- Flexible Fanfold Design: 50 ft. continuous coverage speeds re-siding prep
- Square Edge Fit: Flush seams for smooth sheathing under new siding
- Environmental Certifications: GREENGUARD Gold; listed in ENERGY STAR Seals and Insulates
Please check the Product Data Sheet Here
Specifications Table:
| Specification | Details |
|---|---|
| Insulation Type | Foam Board Insulation (XPS) |
| Insulation R-Value | R-1 |
| Compressive Strength | 25 psi |
| Thickness | 0.25 in (1/4 in.) |
| Width | 48 in |
| Length | 50 ft |
| Coverage Area | 200 sq ft |
| Edge Profile | Square Edge |
| Faced or Unfaced | Unfaced |
| Interior/Exterior Use | Interior (re-siding sheathing) |
| Insulation Location | Re-Siding |
| Compatible Install Surface | Concrete, Plywood, Wood |
| Number of Pieces | 1 |
| Pack Size | 1 |
| Product Weight | 13.2 lb |
| Sheathing Type | XPS |
| Warranty | Limited Lifetime |
| Certifications | GREENGUARD Gold; ENERGY STAR Seals and Insulates listing |
| Environmental Note | Manufactured with a blowing agent with >80% reduction in global warming potential vs. legacy FOAMULAR XPS |
Frequently Asked Questions (FAQ):
Q: Can this be used under new siding?
A: Yes, it’s designed as a re-siding fanfold underlayment to create a smooth, insulated surface.
Q: Is it suitable for damp areas?
A: The XPS foam resists moisture and maintains its R-value after exposure to water.
Q: Do I need special tools to install it?
A: No. Panels are easy to score and cut with common utility knives and install with standard fasteners or foamboard adhesive.
Q: What are the dimensions and coverage?
A: Thickness 1/4 in., width 48 in., length 50 ft; covers approximately 200 sq. ft.
Q: Is it soundproof?
A: No, this product is not rated for STC and does not provide soundproofing.
Streamlined Sheathing for a Flawless Facade
FOAMULAR’s 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. It’s a smart, luxurious layer that makes exteriors feel deliberate and beautifully composed.
Upgrade your re-siding project with FOAMULAR fanfold underlayment for smoother walls and lasting energy savings—add to cart today.
