FOAMULAR R-1 1/4 in. Fanfold XPS Underlayment
Lightweight, moisture-resistant XPS fanfold underlayment designed for re-siding and sheathing applications. The 1/4 in. thick, 4 ft. x 50 ft. board delivers R-1 thermal performance and folds for fast coverage and easy handling.
Key Features:
- Moisture-Resistant XPS: Retains R-value even after exposure to water.
- Easy Handling & Install: Fanfold design cuts and scores simply; no special tools required.
- Re-Siding Ready: Ideal as underlayment/sheathing for re-siding projects.
- Durable Performance: Strong, lightweight board with long-term thermal retention.
- Low-Emitting & Certified: GREENGUARD certified; formaldehyde-free blowing agent with reduced GWP.
Please check the Product Data Sheet Here
Specifications Table:
| Specification | Details |
| Insulation Type | Foam Board Insulation (XPS) |
| Insulation R-Value | R-1 |
| Thickness | 0.25 in (1/4 in.) |
| Width | 48 in. (4 ft.) |
| Length | 50 ft. |
| Coverage Area | 200 sq. ft. |
| Edge Profile | Square Edge |
| Faced or Unfaced | Unfaced |
| Compatible Install Surface | Concrete, Plywood, Wood |
| Interior/Exterior | Interior; commonly used for re-siding underlayment |
| Number of Pieces | 1 |
| Pack Size | 1 |
| Product Weight | 13.2 lb |
| Sheathing Type | XPS |
| Insulation Features | Formaldehyde Free; GREENGUARD Certified; Low water absorption; High R-value retention |
| Warranty | Limited Lifetime |
Frequently Asked Questions (FAQ):
Q: What are the dimensions and coverage?
A: Each fanfold measures 1/4 in. thick, 4 ft. wide, and 50 ft. long, covering 200 sq. ft.
Q: Where can I use this product?
A: Commonly used as re-siding underlayment or insulating sheathing over wood, plywood, or concrete surfaces.
Q: Is it faced?
A: No, this product is unfaced XPS foam board.
Q: How moisture resistant is it?
A: XPS construction provides low water absorption to help maintain R-value in wet conditions.
Q: Do I need special tools to install?
A: No. It scores, snaps, and cuts easily with standard utility knives.
Streamlined Sheathing with a Sleek, Modern Edge
This fanfold insulation creates a crisp, continuous plane behind new siding, elevating exteriors with a polished, tailored finish. I love its subtle flexibilitythe panels fold effortlessly to glide across large walls, minimizing seams and visual clutter. Pair it with fiber-cement or cedar cladding to achieve a refined envelope and improved comfort. Its a quiet luxuryperformance you feel, with a look thats impeccably composed.
Upgrade your re-siding project with FOAMULAR fanfold insulation for faster installs, lasting R-value, and a cleaner finishadd it to your cart today.
Installation
