Which is better for exterior walls?

The Johns Manville R-13 is the better fit for 2x4 exterior walls, because its R-13 thickness matches the cavity and its kraft facing is rated for moisture control. Use the Knauf R-19 only if the wall is deep enough for 6.25 in.

Which has a higher R-value?

The Knauf EcoRoll is R-19; the Johns Manville roll is R-13. Higher R-value means more resistance to heat flow, but the Knauf roll needs a deeper cavity.

Is the Knauf roll worth the extra cost?

No Knauf price was given, so the comparison cannot be settled on cost alone. If the price gap is small and your framing is 2x6, the extra R-value and easier handling favor the Knauf.

Which is less itchy to install?

The Knauf EcoRoll, which is described as soft to touch, easy to cut and less itchy. The Johns Manville roll uses standard glass fibers.

Are both formaldehyde-free?

Yes. Johns Manville is formaldehyde-free and GREENGUARD certified; Knauf uses an ECOSE binder and is GREENGUARD Gold certified.

Which is better for sound control?

Both reduce sound transmission. The Knauf roll is marketed for between-floor and interior-wall sound control, which suits bathrooms, bedrooms and theater rooms.

Johns Manville R-13 Kraft Faced Insulation vs Knauf EcoRoll R-19 Insulation Roll

Buy the Johns Manville R-13 roll for exterior walls and 2x4 cavities, where its kraft facing controls moisture and R-13 fits the framing. Buy the Knauf EcoRoll R-19 for interior walls and between floors, where the higher R-value and softer, less itchy glass wool are easier to work with. On price, the Johns Manville roll ranged from $66.49 to $93.22 between October 31 and November 2, 2026; no current Knauf price was given, so compare it at checkout before deciding.

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