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FOAMULAR 1/4 in. x 4 ft. x 50 ft. R-1 Fanfold Rigid Foam Board Insulation Sheathing

  • Saves energy and resists moisture with limited lifetime warranty
  • Reduce gaps and eliminate drafts with film faced uniform surface
  • Folded hinge at 24" intervals to ease application at job site
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Product Overview

Home with pink outline and Owens Corning logo

A Home is a Fortress

It keeps comfort and safety in - and the other stuff out. Help create the year-round protection every home deserves with proven solutions that work where and when you need them most.

close up of Owens Corning Foamular with water beads

Owens Corning FOAMULAR XPS

FOAMULAR is a rigid insulation board made of extruded polystyrene. XPS for short. Compared to EPS products, FOAMULAR XPS has 25% more insulating power and is 10 times more water resistant.

Cutaway image of a house with Foamular installed in different locations

Choose Above- and Below-Grade Protection

FOAMULAR provides continuous insulating power around the entire home from the foundation to the roofline and all kinds of spaces in between.

man installing fiberglas insulation  over Foamular

Insulating Basement Walls

FOAMULAR is the easy-to-install insulating solution for basement walls. Get added comfort with PINK Fiberglas insulation and finish with drywall board.

man installing Foamular in exterior foundation application

Insulating Foundation Walls

FOAMULAR is ideal for insulating exterior foundation walls. Extremely durable, it can withstand up to 15-25 psi and resists common acid soils and decay.

man installing siding over Foamular

Insulating Under Exterior Siding

FOAMULAR provides a higher R-value per inch than other materials commonly used for exterior wall sheathing.

man installing Foamular fanfold insulation

Also Available in Fanfold

FOAMULAR Fanfold is generally intended for use as a backer board for residing applications and comes in 50-foot sections for a faster install.

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Superior Moisture Resistance

Virtually impervious to moisture. FOAMULAR has up to 10X more resistance to water than EPS insulation.

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Durable, Yet Flexible

A wide range of compressive strengths –up to 100 psi – to handle heavy loads.

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Easy to Cut, Form and Fit

Easy to handle, score, cut and install; no special tools needed.

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Outstanding Insulating Properties

High, stable R-value (5 per inch of product thickness) - more than wood fiber, plywood or 1/2” gypsum board.

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Sustainable

Foamular is certified to meet indoor air quality standards under the stringent GREENGUARD Gold Certification Program.

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Lifetime Guarantee

The only XPS with a limited lifetime warranty that guarantees a minimum 90% of R-value for the life of the product.

FOAMULAR Extruded Polystyrene (XPS) Rigid Foam Insulation offers a comprehensive line of products in a wide choice of sizes, thicknesses and edges with a lifetime limited warranty for the life of the home or building. The products are easy to handle, score, cut and install and no special tools are needed. Products can be used on wood, steel framing or concrete walls. FOAMULAR XPS resists moisture and retains R-value even after exposure to standing water and wet soil. Only XPS foam to be GREENGUARD gold certified and the first XPS foam certified by Scientific Certification Systems (SCS) to contain a minimum of 20% recycled content.
  • Dimensions: 1/4 in. x 4 ft. x 50 ft.
  • Application: backer board for under new or replacement siding
  • Closed cell lightweight foam board
  • Thermal performance of R1
  • Click here to shop Loctite foamboard adhesive
  • FOAMULAR 150 and 250 are available in various thicknesses and R-values, the difference is the compressive strength. FOAMULAR 150 has a compressive strength of 15 psi and FOAMULAR 250 is 25 psi
  • FOAMULAR is not rated for STC (sound transmission) and does not have any soundproofing properties. Owens Corning fiberglass batts and rolls are great options for acoustic applications.
  • When using FOAMULAR or any low perm insulation, always verify the moisture vapor flow and dew point characteristics of the wall system.  Please check your local building codes for vapor retarder/barrier information.
  • If being used in an interior construction application, painting the FOAMULAR is not recommended as FOAMULAR cannot be left exposed and will need to be covered by a 15 minute thermal barrier such as drywall.
  • If being used for crafts, acrylic or latex based paints can be used with FOAMULAR products.
  • If you're looking to insulate your garage door, Owens Corning Garage Door Insulation Kit is an easy, fast and affordable way to keep your garage warm in winter and cool in the summer.
  • If you’re looking to ventilate your attic rafters, Owens Corning Raft-R-Mate is a XPS foam vent designed to assure unrestricted airflow from the soffit to the ridge vent.
  • FOAMULAR is available in two edge configurations:
  • Square Edge - designed to fit flush next to adjoining boards
  • Scored Square Edge - comes with 3 factory scores, so that you can take a 4' sheet, break it in two and have two, 2' wide sheets (middle score), or you can break it into three 16" wide pieces by snapping at the left and right score.
  • Click here to shop Loctite foamboard adhesive
  • Click here to learn more about Eco Options and Energy Efficiency

Info & Guides

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FOAMULAR 1/4 in. x 4 ft. x 50 ft. R-1 Fanfold Rigid Foam Board Insulation Sheathing

Compare Similar Foam Board Insulation

Top Rated24 in. x 1 in. x 48 in. R5 Radiant Acoustic Insulation Kit - STC 19 (5-Piece)19 in. x 150 ft. Sticky Mesh Heavy Duty
current product
FOAMULAR 1/4 in. x 4 ft. x 50 ft. R-1 Fanfold Rigid Foam Board Insulation Sheathing
BrandSilveRboardSTYRO IndustriesOwens Corning
Name24 in. x 1 in. x 48 in. R5 Radiant Acoustic Insulation Kit - STC 19 (5-Piece)19 in. x 150 ft. Sticky Mesh Heavy DutyFOAMULAR 1/4 in. x 4 ft. x 50 ft. R-1 Fanfold Rigid Foam Board Insulation Sheathing
Price
$3720
/package
$8704
Ratings
(240)
(52)
(100)
Product Thickness (in.)1 in0.08 in0.25 in
Insulation Location2x4 Wall,2x6 Wall,2x8 Wall,Attic,Basement,Ceiling Insulation,Exterior Sheathing,Garage,Metal Building,Re-SidingBasement,Ceiling Insulation,Exterior Sheathing,Exterior Wall,Exterior Wall Foundation,Interior Ceiling,Interior Wall,Wood SidingRe-Siding
Insulation R-ValueR5 R1
Insulation FeaturesFormaldehyde Free,Vapor RetardantMold ResistantFormaldehyde Free
Sheathing TypeEPSEPSXPS
Compatible Install SurfaceCement,Concrete,Existing Drywall,Existing Insulation,PlywoodCement,Concrete,Existing Drywall,Existing Insulation,Fiberglass,Plywood,WoodConcrete,Plywood,Wood
Faced or UnfacedFacedUnfacedUnfaced
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Specifications

Dimensions

Cover Area Per Bag (sq. ft.)
200 ft²
Coverage Area (sq. ft.)
200 ft²
Product Length (ft.)
50 ft
Product Thickness (in.)
0.25 in
Product Width (in.)
48 in

Details

Compatible Install Surface
Concrete,Plywood,Wood
Faced or Unfaced
Unfaced
Insulation Features
Formaldehyde Free
Insulation Location
Re-Siding
Insulation R-Value
R1
Insulation Type
Foam Board Insulation
Interior/Exterior
Exterior
Number of Pieces
1
Pack Size
1
Product Weight (lb.)
13.2 lb
Sheathing Size
50 ft. x 0.25 in. x 48 in.
Sheathing Type
XPS

Warranty / Certifications

Warranty Information
Limited Lifetime

Questions & Answers

Typical questions asked about products:

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Customer Reviews

  • 4.6
    out of 100 reviews
  • 100% recommend this product
Filter by:
Showing 1-10 of 100 reviews
Easy to Install
This insulation has a uniform consistency and is easy to install. Its compact packaging makes it easy to transport. I used a staple gun and box cutter to install. I would buy again.
by Steve
    • Recommended Product
    Product has a uniform consistency worked great
    Product has a uniform consistency worked great
    by Blessedsam
    • Verified Purchase
    • Recommended Product
    1 person found this helpful
    Easy and quick to install.
    Easy and quick to install.
    by diamondsmom
    • Verified Purchase
    • Recommended Product
    Worked great for my obscure purpose of insulating reptile tanks from the outside. Only complaint...
    Worked great for my obscure purpose of insulating reptile tanks from the outside. Only complaint is I wish it came in 2x4 pieces. Only need 6ea 2x4 sections. I still have 38 feet left LOL.
    by SnakeMan
    • Verified Purchase
    • Recommended Product
    3 people found this helpful
    I used the insulation for u fee out pool. Worked...
    I used the insulation for u fee out pool. Worked great and it was priced decent.
    by HomeDepotCustomer
    • Verified Purchase
    My garage has no ceiling and I bought 6 of these to lay on top of the rafters. When I finished th...
    My garage has no ceiling and I bought 6 of these to lay on top of the rafters. When I finished the center section over the work shop there was about a 5 or 6 degree drop in temperature compared to the front third and the back third of the garage.
    by Shotei
    • Verified Purchase
    • Recommended Product
    Rating provided by a verified purchaser...
    Rating provided by a verified purchaser
    by HomeDepotCustomer
    • Verified Purchase
    I used this in a closet I and it did the job by keeping the airflow out
    I used this in a closet I and it did the job by keeping the airflow out
    by Mop
    • Verified Purchase
    • Recommended Product
    Nice to work with and get into small places...
    Nice to work with and get into small places
    by HomeDepotCustomer
    • Verified Purchase
    Rating provided by a verified purchaser...
    Rating provided by a verified purchaser
    by HomeDepotCustomer
    • Verified Purchase
    Showing 1-10 of 100 reviews