Rockwool Safe'N'Sound R11
Rockwool Safe'N'Sound R11 is a semi-rigid stone wool batt purpose-built for acoustic control. Its dense, tangled fiber structure absorbs cavity resonance far more effectively than standard fiberglass, making it the batt we specify by default across sound-rated wall, ceiling, and floor assemblies. Friction-fits into standard 2×4 stud cavities and 16" or 24" on-center framing with no stapling required.
- Purpose-Built for Sound: Engineered specifically for acoustic and fire performance rather than thermal R-value alone — denser than standard fiberglass batt for better cavity absorption.
- Friction-Fit Install: Cuts easily 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, keeping absorption performance consistent long-term.
- Fits 16" or 24" O.C. Framing: Sized for both standard 16" and 24" on-center stud/joist spacing — one product covers both layouts.
Online orders up to 99 bags. For anything larger, call (415) 864-4440 and we'll price the project with you.
Freight shipments include a $100 freight-and-handling charge.
Safe'N'Sound R11 Specifications
- R-Value
- R-11
- Thickness
- 3"
- 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
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
Safe'N'Sound R11 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.
Estimated STC Gauge
Compare how the Safe'N'Sound R11 performs across assembly tiers. Select an assembly below to see the estimated STC score.
Single 5/8" drywall each side, no insulation.
Estimated STC — Planning use only
This value is an approximate assembly projection, not a project-specific assessment, certified laboratory test result or performance guarantee. Actual performance varies with the complete assembly, installation, flanking paths, penetrations and site conditions.
- 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 Safe'N'Sound R11 compares
| Model | R-Value | Density | Best For | Price |
|---|---|---|---|---|
| Safe'N'Sound R11this | 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 |
| Comfortbatt R15 | R-15 | High (acoustic-grade) | Maximum thermal + acoustic performance | $69.00 / bag |
| Standard Fiberglass Batt | R-11 to R-15 | Low | Budget thermal-only projects | $40–$60 / bag |
Applicable Assemblies
See where the Safe'N'Sound R11 fits — from budget baseline to studio-grade isolation.
Best — Drywall + Studs + Safe'N'Sound R11 + Clips & Channels + MLV + Drywall + Green Glue + Drywall
Drywall · 2×4 framing · Rockwool Safe'N'Sound R11 · Isolation Clips & Channels · 1 LB MLV · 5/8" drywall · Green Glue · 5/8" drywall.
Better — Drywall + Studs + Safe'N'Sound R11 + Clips & Channels + Drywall + Green Glue + Drywall
Drywall · 2×4 framing · Rockwool Safe'N'Sound R11 · Isolation Clips & Channels · 5/8" drywall · Green Glue · 5/8" drywall.
Good — Drywall + Studs + Safe'N'Sound R11 + Clips & Channels + Drywall
Drywall · 2×4 framing · Rockwool Safe'N'Sound R11 · Isolation Clips & Channels · single 5/8" drywall.
