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Owens Corning FOAMULAR R-1 Extruded Polystyrene Fanfold Underlayment Insulation, 1/4 in. x 4 ft. x 50 ft., Square Edge

Owens Corning FOAMULAR R-1 Extruded Polystyrene Fanfold Underlayment Insulation, 1/4 in. x 4 ft. x 50 ft., Square Edge

$35.28 $70.55

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SKU: CSKJ321805296219
Category:

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

Shipping Info Standard Shipping
Cost: $25/Free Shipping We offer free shipping on orders over $30. Please check the free - shipping eligibility at checkout.
Delivery Time: It usually takes [3-5] business days for standard shipping. Please note that this is an estimated time frame and may be affected by local holidays, and unforeseen circumstances.

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