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
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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

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4.2 ★★★★★
Based on 21 reviews
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Luis n Dee
San Leandro, US
★★★★★ 5
Love the benefits of tallow! It’s all I use!
Scent: Lavender
I am a loyal Lotus customer having their face tallow cream on authorship. It’s all I use on my skin & for my teenage daughter. Surprised when I saw they had their bars on Amazon so I placed an order. They are wonderful tallow bars just like I’d expect from Lotus! Smooth, creamy & lather so beautifully! My skin felt so clean & moisturized after my bath. No nasty chemicals, all natural skincare! Definitely buy these bars! I don’t have any skin conditions or concerns I just would rather use natural high quality ingredients, but I can see if you have sensitive skin or any skin issues this would help! Thank you for making high quality skincare!
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Reviewed in the United States on May 22, 2026
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Verified Purchase
Rissa89
Lowell, US
★★★★★ 5
Worth the price!!
Scent: Unscented
I honestly love this soap. I have it in a pure cotton pouch and that helps with the lather. Yes, the bars are small, but these three have lasted me almost 5 months. For the ingredients in it, and how it makes your skin feel, it is worth the price. I’m running low so will be replenishing soon. Far better than your basic bar soap from the store!
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Reviewed in the United States on May 20, 2026
J
Verified Purchase
Jacob
Bozeman, US
★★★★★ 5
Good Product
Scent: Unscented
Honestly one of the better bar soaps I’ve tried in a while. It’s priced a little higher than what you’d grab off a drugstore shelf, but you can tell pretty quickly that you’re getting something different it lasts longer, feels more substantial, and actually does something for your skin rather than just cleaning it. The lather is rich without feeling heavy, and after a few days of use you notice your skin staying softer without needing to reach for lotion right after. If you’re on the fence about upgrading your soap, this one’s worth trying.​​​​​​​​​​​​​​​​
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Reviewed in the United States on May 3, 2026
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Verified Purchase
fingercast
Fort Morgan, US
★★★★★ 4
Great soap but does not last long
Scent: Unscented
Good soap. Lathers well. Does not last long for the price.
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Reviewed in the United States on May 11, 2026
S
Verified Purchase
Sarah
Whiting, US
★★★★★ 5
I’ve never loved a bar of soap so much.
Scent: Unscented
For starters, I suffer with severe sensitive skin, Eczema (which also has a huge gut health component) - however I’ve been struggling pretty bad the last few months. In my search to find more natural and nontoxic options, I stumbled upon castile soap - I’ve been using it to wash my dishes, clothes, skin. Finding out that the alkalinity of the soap can destroy sensitive skin barriers (even with diluting). I think it is been the leading cause of my skin dryness. (Despite lathering up with things like organic Shea butter and castor oil). I was getting very frustrated and very stressed and I found this family owned company. I’ve always wanted to try more tallow products, and know how amazing honey and castor oil is for health and rejuvenation (inside and out). I figured what the heck this is a pretty decent price. When I say I do not want to stop using the bar so I mean it like it is now becoming a struggle for me to get out of the shower because I want to keep blathering up because it feels so good. As a bartender and someone who hates having dirty hands - I really hate washing my hands, despite how much I feel obligated to do it. I’m contemplating bringing a bar of soap With me wherever I go so that I have good soap to use 😆. I’m about to buy some from my mom and try other products. I will update if my skin issues have subsided (in a month or so I reckon). I am getting an Eczema patch on my stomach/torso area, my inner thigh to my knee, and back of legs as well. As well as for the last month despite how much dry skin I take off my face, And how much castor oil I rub in - even with a moist appearing face - the flaky skin pokes through. I immediately felt soft skin upon using this product on my face. Normally, I would test out a small area, but with only a few ingredients I was like screw it. I ran out of soap and it’s either that or using watered down castile. Please give this a try. I cannot attest for the scented versions. Also, I saw someone say that it burned their eyes? Castile burns my eyes - this, does not. (And I probably scrub my eyes harder than I should post makeup remover - which is a balm - and just on the eyes).
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Reviewed in the United States on January 3, 2026

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