Skip to content
Johns Manville Unfaced Formaldehyde-Free Fiberglass Insulation Batts, Multiple R-Values
Regular price $56.32Orders start at $399 — combine any items to reach the minimum. Learn more
Johns Manville Unfaced Formaldehyde-Free Fiberglass Insulation Batts, Multiple R-Values
Johns Manville Unfaced Fiberglass Insulation Batts are formaldehyde-free thermal and acoustical insulation made of long, resilient glass fibers bonded with a thermosetting resin. Sold by the bag in six size/R-value options from R-11 to R-21 for walls, floors and ceilings, they install between framing in vertical or horizontal applications. Kraft or foil faced variants are available separately in the JM line.
Key Features:
- Formaldehyde-Free: Will not off-gas formaldehyde in the indoor environment.
- Thermally Efficient: Provides effective resistance to heat transfer with R-values up to R-49 (RSI-8.6) in the JM line.
- Sound Control: Reduces transmission of sound through exterior and interior walls and floor or ceiling assemblies.
- Noncombustible Glass: Made of durable inorganic glass fibers that are fire resistant and noncombustible.
- Dimensionally Stable: Bonded fibers will not slump in the wall cavity, settle or break down in normal applications.
- Noncorrosive: Will not rot, mildew, deteriorate or corrode pipes, wiring and metal studs.
Specifications Table:
| Specification | Details |
|---|---|
| Brand | Johns Manville |
| Sell unit | 1 bag |
| Product line | JM Unfaced Fiberglass Insulation Batts |
| Available sizes | ['R-11, 3.625 in. x 16 in. x 96 in.', 'R-13, 3.5 in. x 15 in. x 105 in.', 'R-13, 3.625 in. x 16 in. x 96 in.', 'R-15, 3.5 in. x 16 in. x 96 in.', 'R-19, 6.5 in. x 24 in. x 48 in.', 'R-21, 5.5 in. x 16 in. x 96 in.'] |
| Material | Unfaced fiberglass (long resilient glass fibers bonded with thermosetting resin) |
| Color / finish | Unfaced |
| Nominal size | 3.5 in. to 6.5 in. thick, 15 in. to 24 in. wide, 48 in. to 105 in. long by item |
| Thickness | 3.5 in. to 6.5 in. by item |
| R-value range | R-11 to R-21 for the items listed (up to R-49 in the JM line) |
| Facing | Unfaced (kraft or foil vapor retarder facings available in the JM line) |
| Intended use | Thermal and acoustical insulation for vertical and horizontal applications |
Coverage & How Much You Need:
Each bag covers a variable area depending on R-value and bag count; size the job by matching batt width to stud or joist spacing (15-16 in. for walls, 24 in. for some framing) and length to the cavity, then divide total square footage by the bag coverage listed for that item.
Fit and Compatibility:
Installs between standard wood or metal framing in walls, floors and ceilings. Unfaced batts need a separate vapor retarder where code requires one; JM kraft- or foil-faced batts provide that facing and are sold separately in the line.
Frequently Asked Questions (FAQ):
Q: What sizes and R-values are available?
A: Six unfaced items are listed: R-11 through R-21 in widths from 15 in. to 24 in. and lengths from 48 in. to 105 in.
Q: Is this insulation formaldehyde-free?
A: Yes, it is formaldehyde-free and will not off-gas formaldehyde in the indoor environment.
Q: Does it help with sound?
A: Yes, it reduces sound transmission through exterior and interior walls and floor or ceiling assemblies.
Q: Do I need a vapor barrier?
A: These batts are unfaced, so add a separate vapor retarder where your code requires one, or use JM kraft or foil faced batts.
Q: How do I calculate how many bags I need?
A: Multiply the wall or ceiling area in square feet and divide by the bag coverage listed for your chosen R-value and size.
Q: Will the batts sag over time?
A: No, the bonded glass fibers are dimensionally stable and will not slump, settle or break down during normal applications.
Expert Verdict — Reviewed by the SuperArbor Pro Desk
Choose batt thickness to match the cavity depth: 3.5 in. for 2x4 walls (R-11 to R-15) and 5.5 in. to 6.5 in. for 2x6 walls (R-19 to R-21). Fill edges completely without compressing the batt, since compressed fiberglass loses R-value. In humid climates or conditioned assemblies, pair unfaced batts with a smart or poly vapor retarder as your code requires.
Wear gloves, long sleeves, eye protection and a dust mask when handling fiberglass insulation to avoid skin and respiratory irritation.
Insulate walls and ceilings with Johns Manville unfaced formaldehyde-free fiberglass batts in six R-value options.
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.
