16.25 in. × 48 in. format for 16 in. o.c. steel studs per USA TDS
Key features
R-15 at 3.5 in. in the steel-stud thermal table
Flexible-edge semi-rigid stone wool; 0/0 ASTM E84 per manufacturer sheet
Technical specifications
| R-Value | 15.0 |
|---|---|
| Thickness | 3.5 in |
| Width | 16.25 in |
| Length | 48.0 in |
| Coverage | 65.0 sq ft/pack |
| Material | Stone wool (basalt and recycled steel slag) |
| Fire rating | Noncombustible per ASTM E136; Flame Spread 0 / Smoke Developed 0 per ASTM E84 on ROCKWOOL USA Comfortbatt TDS (05-2025). |
| Sound rating | Stone wool cavity fill improves sound damping versus lightweight empty metal stud bays; assembly STC depends on layers, resilient channels, and seals. |
| Density | >1.8 lb/ft³ per ASTM C167 on ROCKWOOL USA Comfortbatt TDS (05-2025). |
| Framing width | 16" OC |
| Construction type | Steel stud framing |
| Application area | Exterior and interior steel-stud walls, ceilings, and similar framed cavities per ROCKWOOL when the 16.25 in. × 48 in. R-15 module applies. |
Product details
Light-gauge metal framing has a different clear width than wood: forcing a wood-module batt into a steel bay invites buckled faces, thermal shorts, and acoustic leaks. ROCKWOOL documents a dedicated steel-stud format at 16.25 in. width × 48 in. length for 16 in. on-center metal framing, which is the geometry RXCB351625 carries with R-15 / 3.5 in. thickness.
Thermal performance is still labeled per the ASTM C518 table in the Comfortbatt USA sheet—R-15 at 3.5 in. appears in the steel-stud column grouping. Whole-wall R-value for metal construction must account for steel bridging, clip systems, and any continuous exterior insulation in your modeled assembly.
Reaction to fire remains the Comfortbatt baseline: noncombustible to ASTM E136 and 0/0 flame spread and smoke developed to ASTM E84 in the manufacturer PDF. Coordinate rated assemblies separately when the partition requires a listing.
Installation discipline includes managing deflection, avoiding compressed insulation behind heavy MEP, and keeping the air barrier plane continuous at joints and penetrations—especially in hybrid wood/metal transitions on podium or retrofit work.
Coverage is commonly quoted near 65 square feet per package for this SKU naming; confirm on the master-pack label before locking deliveries.
Use https://www.rockwool.com/siteassets/o2-rockwool/documentation/technical-data-sheets/residential/comfortbatt-exterior-wood-and-steel-stud-thermal-batt-insulation-techdata-us.pdf as the authoritative dimensions and compliance source.
Documents & certifications
Technical data sheet
Manufacturer-tested R-value, coverage, fire notes, and handling—use for submittals, RFIs, and field QA.
Download PDF (opens in new tab)Certifications & compliance
ASTM C665 Type I compliant, ASTM E136 noncombustible, ASTM E84 flame spread 0 / smoke developed 0 (Note 1 Class A per IBC on TDS), ASTM C518 thermal resistance per published R-thickness table, GREENGUARD Gold per ROCKWOOL Comfortbatt marketing
Frequently asked questions
Why is this batt 48 in. long instead of 47 in.?
Why is this batt 48 in. long instead of 47 in.?
ROCKWOOL lists 48 in. length for the 16 in. on-center steel-stud Comfortbatt module versus 47 in. for typical wood-stud batts. Match SKU dimensions to your framing system.
Can I install RXCB351625 in wood studs?
Can I install RXCB351625 in wood studs?
This width targets steel-stud bays. For wood studs on 16 in. o.c., use the 15.25 in. wide wood-format SKUs so you avoid over-compression or misaligned joints.
Does R-15 in metal studs equal wood-wall R-15?
Does R-15 in metal studs equal wood-wall R-15?
The labeled R-value applies to the insulation product. Metal framing increases thermal bridging; model whole-wall U-factor or assembly R-value for compliance.
Where are official tolerances listed?
Where are official tolerances listed?
Refer to the current Comfortbatt USA technical data sheet PDF on rockwool.com for dimensions, standards, and application statements.