Which is better for an exterior 2x4 wall?

The Knauf Kraft Faced batt. Its facing acts as the vapor retarder, which code typically requires on exterior walls in cold climates. The unfaced R13 needs a separate membrane.

Do I need a vapor barrier with the unfaced R13?

Yes, on exterior walls in most climates. Add a separate vapor retarder or use a faced product. On interior partitions, unfaced is fine.

Is the Knauf worth the extra cost?

Usually yes for exterior walls, because it saves buying and installing a separate vapor retarder. For interior walls, the cheaper unfaced batt does the same job.

Both last decades when kept dry and covered. Fiberglass does not rot. The kraft facing can tear during install, so handle it carefully.

Can I use faced batts in a basement?

Check local code first. Faced kraft can trap moisture against concrete. Many basement jobs call for unfaced batts with a separate vapor barrier.

Are both GREENGUARD certified?

Yes. Both list GREENGUARD certification, so both meet the same low-emission standard for indoor air quality.

R13 Unfaced Fiberglass Batt Insulation vs Knauf Kraft Faced Fiberglass Insulation Batt

Buy the Knauf Kraft Faced batt for most 2x4 wall jobs. Its factory-attached kraft facing acts as a vapor retarder, so you skip a separate membrane on exterior walls. The R13 Unfaced batt is the better pick for interior partitions, odd cavities and anywhere you plan to add your own vapor barrier. Compare the current per-bag prices across stores before you commit, since batt pricing moves with pack size and R-value.

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