Owens Corning FOAMULAR R-1 Extruded Polystyrene Fanfold Underlayment Insulation, 1/4 in. x 4 ft. x 50 ft., Square Edge
SKU: 59277810533

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

Sale price$63.49 Regular price$70.55
Save 10%

Shipping Estimate
USA
  • USA
  • CAN

Ships within 48 hours · Estimated delivery Jul 6 - Jul 11

Promo Codes Available:

For Your Every Summer RSVP, with Code: SUMMER15

Description

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

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 flexibility—the 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. It’s a quiet luxury—performance you feel, with a look that’s impeccably composed.


Upgrade your re-siding project with FOAMULAR fanfold insulation for faster installs, lasting R-value, and a cleaner finish—add it to your cart today.

Installation

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 59277810533

Discover Niche Categories That Outsell

Top-Converting Item to Boost Your Average Order

4.5 ★★★★★
Based on 1537 reviews
Sort
Highest Rating
Newest First
Oldest First
Product Reviews
H
Verified Purchase
Heidi Godines
Chelsea, US
★★★★★ 5
Great floating display shelf
Color: Brown, Size: 55.1"W x 10.3"D x 1.8"H, Set of 1
Perfect display shelf for trinkets or memorabilia. Placed this over our wall mounted TV for our football collection. Looks great and was easy to mount. The size is perfect. Great value for the money.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 15, 2026
A
Verified Purchase
ariel brammer
Carnegie, US
★★★★★ 5
Cute but one is broken
Color: Brown, Size: 35.7"W x 10.3"D x 1.8"H, Set of 2, Color: Brown, Size: 35.7"W x 10.3"D x 1.8"H, Set of 2
Update: they sent me new ones and they seem to be holding up, thank you! I really wanted to love these but one of them came bent so I can’t use it because I’m worried it’s going to ruin the wall. It’s slanted so far down but the one that didn’t come bent works great and looks really cute
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on January 7, 2026
R
Verified Purchase
R
Lake Worth, US
★★★★★ 5
A birthday gift that made someone happy.
This was bought as a birthday gift, good quality, very sturdy, and the recipient loved it highly recommend this product.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 25, 2026
S
Verified Purchase
S.landia_Librarian
Massapequa, US
★★★★★ 1
Issues with mounting the shelves, big time
Color: Brown, Size: 55.1"W x 10.3"D x 1.8"H, Set of 2
I bought the 55 inches floating shelves. I have an area above my linen cabinet that I wanted to utilize for storage and books in my hall. I did my measuring, figured out spacing. Marked everything off to do 3 total shelves (bought two boxes). A couple of spots screwed into a stud, and the others I had to install the plastic mount things. I had used those before so I just did the predrill then tapped them in, finished off by screwing the mount flush with the wall. I grabbed the first bracket and decide to start with a screw that had one of the inset mount things (sorry the correct term is escaping me). It never once occurred to me to check that the plastic mount and screw would not work. We’ll surprise! I tried and tried to get the screw to screw thru the mount, the mount is the rigid plastic thoe that is supposed to split when the screw goes through. Well something wasn’t engineered properly on the mounts cuz they would not thread a screw. They would not split. I even went into my garage and tried different screws I had to see if maybe it was just too big…or something. Then I started just prying it apart and could not get it to split like it’s supposed to, the tip piece broke off before the piece split. I have never had this situation before. I now have a bunch of these, that leave huge holes in my wall, where I measured out for a shelf to go. I’m not a huge DIYer so now I’m trying to figure out if I can salvage this situation but I’m afraid that if I get different mounts they will be too small for the already created holes, or they will fit the hole but because it’s screwing into dry wall, the drywall already has threads from the other mount, will it strip if the threads aren’t 100% the same. Oooooor am I going to have to patch up and paint that wall, then buy new mounts and attempt to try again….which I will now have to set the shelves at a different height so I don’t screw into the same holes I patched since I don’t trust them…..ugh. I practically want to cry. lol. So if I could give this negative stars I would! I feel stupid due to these having such great reviews by others. Comments of how easy they were to install. I will also mention that a few others mentioned the metal bracket that is mounted to the wall then the shelf slide onto is very flimsy. I could bend it side to side with my hands. The only reason I decided it would be ok is that there are a total of 8 screws in the mount, figured it would be stable enough.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on September 14, 2025
R
Verified Purchase
Rhonda Emmons
Natrona Heights, US
★★★★★ 5
Was so easy to put up.
Love it
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 27, 2026

recommand products