Full-thickness R-38 batt for deep 16 in. o.c. cavities
Key features
19.25 in. width aligned with common deep-joist modules
Unfaced format for project-specific vapor-control strategies
Technical specifications
| R-Value | 38.0 |
|---|---|
| Thickness | 12.5 in |
| Width | 19.25 in |
| Length | 48.0 in |
| Coverage | 51.33 sq ft/pack |
| Material | Fiberglass (PINK Next Gen), unfaced |
| Fire rating | ASTM C665; unfaced glass fibers classified noncombustible per ASTM E136 in manufacturer documentation. Unfaced PINK Next Gen acceptable ICC types I–V per OC literature. |
| Sound rating | Cavity-fill fiberglass improves typical assembly acoustics versus empty framing; final metrics are assembly-dependent. |
| Density | Light-density flexible batt per ASTM C665 manufacturer listings; see TDS for product-specific values. |
| Thermal conductivity | Labeled R-38 at full labeled thickness; see manufacturer TDS (ASTM C518) for tested conductivity. |
| Framing width | 19.25 in. width for 16 in. on-center joist or rafter spacing in nominal 2×10-class depths |
| Construction type | Wood-frame and light-gauge metal-frame cavity construction |
| Application area | Attic floors, ceilings, and deep framed floors per code; not an R-38C depth-limited SKU |
Product details
About 51.33 square feet per package (IDI-listed coverage). Primary use: high-R attic floors, flat ceilings, and deep joist cavities on 16 in. on-center framing where a full-thickness R-38 batt is appropriate and the 19.25 in. width matches the common 14-1/2 in. clear span logic for that module with deeper members.
At 12.5 in. labeled thickness, this is a true high-R batt—not the R-38C depth-limited line—so make sure the structural cavity actually provides that depth with room for venting, services, and finishes without crushing the insulation. The 48 in. length supports four-foot staging on lifts and carts common to attic crews.
Unfaced PINK Next Gen keeps kraft orientation off the table: pair the batt with your approved vapor retarder strategy, exterior foam plan, or smart membrane as required by IECC and local amendments.
Manufactured to ASTM C665; unfaced glass fiber is noncombustible per ASTM E136 in manufacturer documentation with ICC types I–V language for unfaced PINK Next Gen. GREENGUARD certification with formaldehyde-free validation and a UL Environment EPD answer typical submittals. Use the linked data sheet for package weights and code references before inspection.
Full-thickness R-38 batts in deep joist modules differ from R-38C depth-limited lines; mixing them on the same takeoff without revisiting cavity depth is a common estimating error in attic retrofits.
Mechanical platforms and storage floors are chronic compression points—either detail raised platforms that preserve labeled thickness or redesign insulation strategy rather than hiding crushed batts.
OSB decks parked tight on deep joists can hide lost loft; split layers around webs and utilities so the assembly still reads the published thickness when raters spot-check with depth gauges.
Submittal discipline: keep the distributor-listed dimensions (12.5 in. × 19.25 in. × 48.0 in.) and about 51.33 square feet per package attached to the same SKU on purchase orders, delivery tickets, and photos for QA. Authoritative tested language and code-oriented statements belong in the current manufacturer technical data sheet at https://www.idi-insulation.com/media/pdfresources/1004907_data_sheet.pdf.
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
GREENGUARD (formaldehyde-free validated), UL Environment EPD, California Title 24 Article 3 insulating materials
Frequently asked questions
E63 versus R-38C batts in the same R family?
E63 versus R-38C batts in the same R family?
E63 is a full-thickness R-38 batt at 12.5 in. labeled depth. R-38C products use thinner labeled thickness to fit constrained cavities while still targeting high-R performance—pick the geometry that matches structural depth and venting.
Will this fit my truss bottom chord depth?
Will this fit my truss bottom chord depth?
Measure the clear cavity after plates, chords, and required vent channel height. If you cannot maintain full labeled thickness, do not force the batt—choose R-38C or another assembly.
How many bags for my attic?
How many bags for my attic?
Divide net insulated attic floor area by about 51.33 square feet per bag and add waste for hips, drops, and mechanical chases—typically five to ten percent unless drawings say otherwise.
Does unfaced R-38 satisfy vapor requirements by itself?
Does unfaced R-38 satisfy vapor requirements by itself?
No. Unfaced batts do not add a vapor retarder. Follow IECC and your designer’s plan for where Class I, II, or III control belongs.