Description
Johns Manville R-30: A Clean First Layer After Insulation Removal
After an attic has been cleared of old or rodent-damaged insulation, the first new layer sits directly on the ceiling drywall, so it should carry a vapor retarder facing down. Johns Manville R-30 kraft-faced batts do exactly that, and at about 10 inches thick they fill a 2×10 joist bay neatly. In coastal areas, R-30 meets the target on its own; inland, many homeowners add an unfaced layer on top later.
Specifications
| Brand | Johns Manville |
|---|---|
| R-value | R-30 |
| Material | Formaldehyde-free fiberglass |
| Thickness | About 10 in. |
| Facing | Kraft paper vapor retarder |
| Common bag size | 16 x 48 in., about 58.7 sq ft |
| Sold by | Bag. Confirm width when ordering |
How Many Bags?
For a 1,000 sq ft attic with 16-inch bags at about 58.7 sq ft: 1,000 ÷ 58.7 ≈ 17, plus about 5% for cuts, so about 18 bags. Call 800-778-3765 and we will confirm the count for your framing.
Installation Tips
- Facing down toward the living space; never add a faced layer over existing insulation.
- Cut batts to fit around blocking and wiring rather than compressing them.
- Seal attic bypasses (plumbing and wiring penetrations) before insulating.
Buy It or Have It Installed
Order JM R-30 here, or let our crew (CSLB #1139733) handle insulation removal and replacement, including rodent-proofing and air sealing. See typical pricing in our attic insulation cost guide.
Johns Manville R-30 Kraft-Faced Fiberglass FAQ
- How much does one bag of Johns Manville R-30 cover?
- A common 16 x 48 inch kraft-faced bag covers about 58.7 sq ft. Other widths cover more or less, so check the bag or ask us.
- Can I add R-30 over my old attic insulation?
- Only with unfaced batts, and only if the old insulation is dry and uncontaminated. Kraft-faced R-30 belongs on a bare attic floor.
