Which is better for attic insulation?

The R-30. At 10 in. thick it delivers R-30, which is the range most attics need. The R-11 is a wall product and would leave an attic under-insulated.

Which is better for 2x4 walls?

The R-11. Its 3.5 in. thickness matches a 2x4 cavity. The R-30 is 10 in. thick and will not fit without compressing it, which cuts its R-value.

How much area does each pack cover?

The R-11 pack covers 155 sq. ft. The R-30 pack covers 69.33 sq. ft. You will need more R-30 packs for the same square footage.

Are both formaldehyde-free?

Yes. Both list formaldehyde-free construction and kraft facing that acts as a vapor retarder.

Is the R-30 worth the extra cost?

Compare price per square foot at the R-value you need, not per pack. For an attic, R-30 is the right product; for walls, the R-11 is the only one that fits.

Do both reduce sound?

The R-30 listing states it reduces airborne sound transmission. The R-11 listing does not make a sound claim, though fiberglass batts generally absorb some sound.

Knauf R-11 Kraft Faced Fiberglass Insulation vs Knauf R-30 Kraft Faced Fiberglass Insulation

Both are Knauf kraft-faced fiberglass batts, so the real choice is R-value and where you're installing. The R-11 batt (3.5 in. thick, 15 in. x 93 in., 155 sq. ft. per pack) fits 2x4 walls; the R-30 batt (10 in. thick, 16 in. x 48 in., 69.33 sq. ft.) is built for attics and ceilings. No prices were provided for either product, so compare store prices on Deal.ai before buying.

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