R-21 Unfaced Fiberglass Batt Insulation (15 in. x 93 in.)
JM R-21 unfaced fiberglass batts deliver thermal performance and sound control for 2x6 wood-stud cavities. Precut to 93 in. for standard 8 ft. walls, each bag covers 67.81 sq. ft. and can be used in walls, floors, and crawlspaces.
Key Features:
- Right-Size for 2x6 Framing: 15 in. wide x 5.5 in. thick batts fit 2x6 wood-stud cavities for a secure friction fit
- Unfaced for Flexible Assemblies: No vapor retarder, making it suitable for layering with existing insulation or where a separate vapor control layer is desired
- Energy & Comfort Upgrade: R-21 helps reduce heat transfer to improve overall energy efficiency
- Sound Control: Helps reduce noise transmission through wall, floor, and ceiling assemblies
- Formaldehyde-Free & Durable Fiberglass: Made with resilient glass fibers; designed not to rot or mildew and to remain dimensionally stable in the cavity
Please check the Product Data Sheet Here
Specifications Table:
| Specification | Details |
| Brand | JM (Johns Manville) |
| Manufacturer | Johns Manville |
| Model / Manufacturer Part # | U1321 |
| Insulation Type | Fiberglass batt |
| Faced or Unfaced | Unfaced |
| R-Value | R-21 |
| Coverage Area | 67.81 sq ft |
| Batt Width | 15 in |
| Batt Length | 93 in (7.75 ft) |
| Insulation Thickness | 5.5 in (5-1/2 in) |
| Fits Wall Size | 2 x 6 wall |
| Stud Spacing Compatibility | 16 in on-center (standard 8 ft wall precut length) |
| Pieces per Bag | 7 pieces |
| Product Weight | 28.6 lb |
| Bag Size | 3.9 ft x 40 in x 15 in |
| Batt/Roll Size | 7.75 ft x 15 in |
| Insulation Features | Friction fit; sound control/soundproofing |
| Application Areas | Walls, floors, ceilings, basements, attics, crawlspaces (new construction and remodels) |
| For Use With | Wood stud framing |
| Flame Spread Index | <25 |
| Smoke Developed Index | <50 |
| Temperature Rating | 850F |
| Water Vapor Sorption | <5% |
| Standards/Certifications | ASTM C665 Type I; ASTM E136; IBC; Energy Star Certified; Greenguard Gold Certified; Indoor Air Quality Certified; NAIMA 16 CFR Part 460; Recycled Content Certified |
Frequently Asked Questions (FAQ):
Q: Is this insulation faced?
A: Nothis is unfaced fiberglass batt insulation (no vapor retarder).
Q: What wall cavity does it fit?
A: Its sized for 2x6 wood-stud framing with 16 in. on-center spacing (15 in. wide batts).
Q: How much area does one bag cover?
A: One bag covers 67.81 sq. ft.
Q: Can I use this in basements, attics, or crawlspaces?
A: Yesit's listed for use in areas such as attics, basements, ceilings, crawlspaces, floors, and interior/exterior walls (where appropriate for fiberglass batts).
Q: Do I need special tools to cut it?
A: Batts can be cut to fit using a utility knife and a straightedge; wear appropriate PPE when handling fiberglass.
Quiet luxury, engineered into the walls
Theres a particular elegance in rooms that feel calmwhere temperature holds steady and sound softens at the edges. These R-21 unfaced fiberglass batts tuck cleanly into 2x6 cavities, creating an invisible layer of comfort that lets your finishes shine. Use them as the quiet foundation behind paneling, plaster, or millwork-heavy spaces where acoustics matter as much as aesthetics. Its the kind of behind-the-scenes upgrade that makes a home feel unmistakably more refined.
Upgrade your comfort and sound controlchoose JM R-21 unfaced batts to efficiently insulate 2x6 wall cavities with reliable coverage per bag.
Warranty
Installation
