Johns Manville R-38 Unfaced Fiberglass Batt Insulation, 64-sq ft Coverage, 24-in x 48-in, U366S

Regular price $98.04

/
Shipping calculated at checkout.

R-38 Unfaced Fiberglass Attic Batt Insulation, 24x48-in

High R-38, unfaced fiberglass batts designed for wood-framed attics, ceilings, and floors. Precut 24-in x 48-in pieces provide 64 sq ft of coverage per package and install easily between 24-in on-center joists for improved energy efficiency and sound control.


Key Features:

  • High Thermal Performance: R-38 batts boost energy efficiency and comfort in attics, ceilings, and floors
  • Unfaced Design: No vapor barrier—ideal for adding over existing insulation where permitted
  • Precut Convenience: 24-in x 48-in batts sized for 24-in on-center framing; simple press-in installation
  • Durable, Healthy Choice: Formaldehyde-free fiberglass that won’t rot, mildew, or corrode pipes/wiring
  • Certified for Indoor Air Quality: GREENGUARD Gold and SCS Recycled Content certified; ENERGY STAR partner

Specifications Table:

Specification Details
R-Value 38
Coverage Area 64 sq ft
Dimensions (each batt) 24 in W x 48 in L x 13 in T
Stud/Joist Spacing 24 in on-center
Faced/Unfaced Unfaced
Insulation Type Fiberglass
For Use in Attics Yes
For Use in Ceilings Yes
For Use in Floors Yes
For Use in Walls No
Formaldehyde Free Yes
Sound Barrier Yes
Vapor Retardant No
ENERGY STAR Certified Yes (program partner)
GREENGUARD Gold Certified Yes
Framing Type Wood studs
Length 48 in
Width 24 in
Thickness 13 in
Package Weight 37 lbs
R-Value per Inch 2.923
Package Count 8 pieces
Package Type Multi-pack
Multi-Pack Quantity 4
Total Package Quantity 32
Warranty 1-year limited
UNSPSC 11162400
Bag Dimensions (L x W x D) 20 x 20 x 50 in

Frequently Asked Questions (FAQ):

Q: How much area does one package cover?
A: Each package provides 64 square feet of coverage with eight 24-in x 48-in batts.


Q: Can these batts be installed over existing insulation?
A: Yes. Because they are unfaced (no vapor retarder), they can be added over existing insulation where local codes allow.


Q: Where can I use this product?
A: It’s designed for attics, ceilings, and floors with 24-in on-center wood framing; not intended for walls or masonry.


Q: Is the insulation formaldehyde-free?
A: Yes, it is formaldehyde-free and GREENGUARD Gold certified for indoor air quality.


Q: What is the thickness of each batt?
A: Each batt is approximately 13 inches thick to achieve R-38.


Luxurious Warmth, Effortlessly Layered

Imagine a cocooned quiet settling over your home as these plush white batts disappear beneath your attic joists. Their generous 13-inch loft creates a serene, insulated envelope that elevates comfort and hushes the outside world. Pair with crisp, painted ceilings and natural wood finishes to accentuate the calm, controlled environment they enable. This is the invisible foundation of refined, luxurious living—comfort engineered with elegance.


Upgrade your attic with JM R-38 batts today for immediate comfort, quieter rooms, and long-term energy savings.

*Third Party Trademarks

All third party trademarks, including logos and icons, referenced on our website and product pages remain the property of their respective owners. Unless specifically identified as such, Arbor's use of third party trademarks does not indicate any relationship, affiliation, sponsorship, or endorsement between Arbor Home and the owners of these trademarks. Any references by Arbor Home to third party trademarks are to identify the corresponding third party goods.

Why choose us

The Arbor Way

• Lowest Prices. Easy Online Shopping. Fast Delivery.

• No lines. No holds. No Hassles.

• America's Largest Inventory Network for All Home Improvement Supplies Nationwide.

• We deliver - town to town, door to door. 


Recently viewed

\