Rockwool Comfortbatt R15
Rockwool Comfortbatt R15 is a semi-rigid stone wool batt that steps up thermal resistance while keeping the same dense fiber structure that makes Rockwool a top acoustic performer. It friction-fits standard 2×4 stud and joist cavities and is a strong fit for projects that want extra thermal value on top of sound control.
- Higher Thermal Value: R-15 rating adds meaningful thermal resistance over R-11 in the same 2×4 cavity depth, without giving up Rockwool's acoustic density.
- Friction-Fit Install: Cuts with a serrated knife and friction-fits snugly into the stud or joist bay — no stapling or wire support needed in most cavities.
- Non-Combustible Stone Wool: Made from basalt rock and recycled slag — naturally fire-resistant and water-repellent, won't sustain a flame or promote mold growth.
- Won't Sag or Settle: Semi-rigid density holds its shape inside the cavity for the life of the assembly.
Contact for pricing
Special-order item. We confirm current pricing, lead time (typically 3–10 business days, longer for custom sizes), and the material, size and finish options available — plus supply-only vs. professional-install pricing. Nothing is charged until you approve the estimate.
Prefer a form? Open the estimate request with this product filled in.
Comfortbatt R15 Specifications
- R-Value
- R-15
- Material
- Stone wool (basalt rock + recycled slag)
- Framing fit
- 2×4 stud cavities, 16" or 24" o.c.
- Density
- Higher than standard fiberglass batt
- Fire performance
- Non-combustible, melting point ~2,150°F
- Water repellency
- Water-repellent, won't support mold growth
- Install method
- Friction-fit; cut with a long serrated knife
- Coverage
- Approx. 60 sq ft per bag
- Pricing
- $69.00 per bag
Stone Wool Knife — Recommended Companion
- Use
- Cutting Rockwool stone-wool insulation batts
- Blade Type
- Serrated, purpose-built for mineral fiber
- Compatibility
- Safe'N'Sound R11, Comfortbatt R13, Comfortbatt R15
- Note
- One knife per crew is standard — additional units for multi-crew jobs
Comfortbatt R15 Project Calculator
Enter your surface square footage — we'll estimate the number of bags needed (each bag covers ~60 sq ft).
Coverage is estimated at 60 sq ft per bag. Add a 10% buffer for cuts, odd bays, and future patching.
STC Gauge
Compare how the Comfortbatt R15 performs across assembly tiers. Select an assembly below to see the resulting STC score.
Single 5/8" drywall each side, no insulation.
- STC 30-39: Loud speech clearly audible next room.
- STC 40-49: Loud speech muffled — normal residential wall.
- STC 50-59: Loud speech barely audible; suitable for offices & multi-family.
- STC 60+: Approaches studio-grade isolation.
How Comfortbatt R15 compares
| Model | R-Value | Density | Best For | Price |
|---|---|---|---|---|
| Comfortbatt R15this | R-15 | High (acoustic-grade) | Thicker 2×4 cavities, added thermal value | $69.00 / bag |
| Safe'N'Sound R11 | R-11 | High (acoustic-grade) | 2×4 walls, default recommendation | $92.99–$95 / bag |
| Comfortbatt R13 | R-13 | High (acoustic-grade) | Thicker 2×4 cavities, added thermal value | Price on request |
| Standard Fiberglass Batt | R-11 to R-15 | Low | Budget thermal-only projects | $40–$60 / bag |
Applicable Assemblies
See where the Comfortbatt R15 fits — from budget baseline to studio-grade isolation.
Best — Drywall + Studs + Comfortbatt R15 + Clips & Channels + MLV + Drywall + Green Glue + Drywall
Drywall · 2×4 framing · Rockwool Comfortbatt R15 · Isolation Clips & Channels · 1 LB MLV · 5/8" drywall · Green Glue · 5/8" drywall.
Better — Drywall + Studs + Comfortbatt R15 + Clips & Channels + Drywall + Green Glue + Drywall
Drywall · 2×4 framing · Rockwool Comfortbatt R15 · Isolation Clips & Channels · 5/8" drywall · Green Glue · 5/8" drywall.
Good — Drywall + Studs + Comfortbatt R15 + Clips & Channels + Drywall
Drywall · 2×4 framing · Rockwool Comfortbatt R15 · Isolation Clips & Channels · single 5/8" drywall.
