Description
CertainTeed R-38: Built for Modern Truss Attics
Most homes built since the 1970s — across the San Fernando Valley, the Inland Empire, Orange County and Las Vegas — have roof trusses spaced 24 inches on center. CertainTeed makes R-38 batts in a 24″ width that drops straight between those trusses, so you cover more attic with fewer pieces, fewer seams and less cutting. It’s our go-to batt for fast, clean attic floor installs.
Specifications
| Brand | CertainTeed |
|---|---|
| R-value | R-38 (R-38C high-density also made) |
| Material | Fiberglass with plant-based binder |
| Thickness | About 12″ (R-38C: about 10¼”) |
| Common bag sizes | 16″ x 48″ ≈ 42.7 sq ft; 24″ x 48″ ≈ 64 sq ft |
| Facings made | Kraft-faced and unfaced |
| Certifications | GREENGUARD Gold |
| Recycled content | Made with recycled glass (CertainTeed states up to 50% recycled materials) |
| Sold by | Bag — confirm width and facing when ordering |
Where to Use It
- Attic floors between trusses — 24″ widths for trusses, 16″ for conventional joists.
- Attic insulation replacement — after old insulation is removed, kraft-faced R-38 goes on the bare ceiling drywall, paper facing down.
- Top-up layers — unfaced R-38 over existing, dry insulation.
How Many Bags?
For a 1,200 sq ft truss attic using 24″ x 48″ bags (about 64 sq ft each): 1,200 ÷ 64 ≈ 18.8, plus 5% waste → about 20 bags. With 16″ bags (about 42.7 sq ft): about 30 bags. Not sure of your spacing? Measure from the center of one joist to the next, or call 800-778-3765.
R-38 and Title 24
R-38 is the prescriptive ceiling insulation level in California’s Title 24 energy code for new homes in climate zones 9 and 10 — which include the San Fernando Valley and the inland LA basin — when ducts are in the attic. It’s also a common upgrade target for existing homes across Southern California. We’ll confirm what your home needs during a free inspection.
Installation Tips
- Kraft facing goes toward the living space, and it’s combustible — never leave it exposed.
- Don’t lay a faced batt over existing insulation; use unfaced instead.
- Keep soffit vents clear with baffles, and keep a gap around non-IC recessed lights and flues.
Buy It or Have It Installed
Pick up CertainTeed R-38 for your own project, or have our licensed team (CSLB #1139733) install new attic insulation for you. Compare with Knauf EcoBatt R-38 or blown-in insulation, and check our attic insulation cost guide.
CertainTeed R-38 FAQ
- Should I buy 16-inch or 24-inch R-38 batts?
- Match your framing. Most modern truss attics are 24 inches on center; many older homes with conventional joists are 16 inches on center.
- What is CertainTeed R-38C?
- R-38C is CertainTeed’s high-density R-38, about 10¼ inches thick, for cathedral ceilings and 2×10 framing where a 12-inch batt won’t fit without compression.
- Is CertainTeed insulation safe for indoor air?
- CertainTeed’s fiberglass batts are GREENGUARD Gold certified, the stricter tier of the GREENGUARD indoor air quality standard.
