Knauf Insulation vs. Owens Corning: An Admin Buyer's Honest Take on Mineral Wool, Pricing, and Hidden Costs

Why I'm Writing This Comparison

I'm the office administrator for a mid-sized construction firm. I manage all our insulation and building material orders—roughly $150k annually across maybe 8 vendors. When I took over purchasing in 2020, I assumed all insulation brands were more or less the same. I was wrong.

In this post, I'll answer the questions I wish I'd asked when I started. This is based on my experience ordering Knauf, Owens Corning, and other brands for projects ranging from small residential lofts to commercial office builds. Prices reflect what I've paid as of Q4 2024; always verify current rates.

Common Questions About Knauf vs. Owens Corning (and More)

1. Is Knauf insulation any good? How does it compare to Owens Corning?

Short answer: Yes, it's excellent. The real question is which one fits your specific project better.

Longer answer from my experience: Knauf's mineral wool (their Earthwool line) uses their ECOSE Technology binder. It's formaldehyde-free and has a noticeably lower odor during installation compared to some other mineral wool products. Owens Corning's Thermafiber is also quality stuff. In a side-by-side test on a commercial job in 2023, we found Knauf's material handled slightly better—it felt less 'dusty' and cut more cleanly. But Owens Corning had a slight edge in availability for certain R-values in our region at the time.

Look, I'm not saying one is universally better. I'm saying for our crew, Knauf was the winner. But we still use Owens Corning for specific orders when Knauf's lead times are longer. It's about having options, not loyalty.

2. How much does Knauf insulation 100mm cost?

Pricing fluctuates, but here's a real data point: As of January 2025, a standard roll of Knauf Earthwool 100mm (R-13 equivalent) was running us about $0.85 to $1.10 per square foot from our main distributor. Owens Corning's equivalent was $0.90 to $1.15. The difference is small, but on a 2,000 sq ft job, that's potentially a few hundred dollars saved.

My tip: Don't just look at the unit price. I've had a vendor offer a 'cheaper' roll that was actually a different density. The total installed cost was nearly the same because we needed more fasteners and support spacing. Ask for the total installed cost estimate.

3. What about fire rating? Which is better?

Both Knauf and Owens Corning mineral wool products are non-combustible. That's a key advantage over fiberglass. For commercial buildings where fire codes are strict, both are safe bets. In our projects, we've specified both interchangeably for fire-rated assemblies without issue. Check the specific product data sheet for your local building code. As of 2024, both comply with ASTM E84 (Class A) for flame spread.

4. Is Knauf a good choice for pipe and acoustic insulation?

Yes. We used Knauf's pipe insulation for a new HVAC system in a 40,000 sq ft office building in 2022. The contractor specifically requested it because they said it held up better to humidity and didn't sag over time. For acoustic insulation, their Earthwool Acoustic rolls are solid. I've seen them used in recording studios and office partition walls. The sound transmission class (STC) ratings are impressive, but don't assume any one product will 'eliminate all noise'—that's an overpromise no manufacturer can keep.

5. How do I choose between mineral wool and fiberglass? (A question you should ask)

Most people start by asking 'Knauf vs. Owens Corning.' The smarter question is 'mineral wool vs. fiberglass.'

Here's the thing: Mineral wool (like Knauf Earthwool or Owens Corning Thermafiber) is denser, better for sound, and non-combustible. Fiberglass (like Knauf Ecobatt or Owens Corning Pink) is lighter, cheaper, and easier to install in attics. If you're doing a loft, fiberglass might be fine. If you're insulating a commercial fire-rated wall, you probably want mineral wool. We've made mistakes by not asking this distinction upfront.

6. Can you just tell me which is cheaper: Knauf or Owens Corning?

I can't give you a single answer because it depends on your region, volume, and relationship with the distributor.

What I can tell you is this: In Q3 2024, I bid out a job that needed 2,000 sq ft of R-19 mineral wool. I got three quotes. The spread was 15% between the lowest (Knauf via one distributor) and the highest (Owens Corning via another). But the lowest quote came from a distributor who had a 3-week lead time—we needed it in 7 days. So the 'cheapest' option would have caused a delay that could have cost us the job. Time is also a cost.

Don't assume 'same specifications' meant identical results across vendors. Each distributor had slightly different packaging (some palletized, some not), which affected our handling costs.

7. Any other gotchas I should know about?

Yes. One that bit me early on: R-value ratings are for optimal installation. If you cram mineral wool into a tight cavity, you lose some of its thermal performance. I learned never to assume the proof represents the final product after receiving a batch of insulation that looked fine but was installed poorly. The R-value in the wall wasn't the R-value on the label. Installation quality is your biggest variable.

This was accurate as of January 2025. The market changes fast—verify current prices and product specs with your supplier.