For DIY acoustic panels, both Rockwool (mineral wool) and rigid fibreglass work extremely well — the choice between them is mostly about availability, density and handling, not a big difference in acoustic performance. In the Rockwool vs fiberglass debate, either material will dramatically outperform foam, so the real win is simply using one of them at the right thickness. Below is what actually separates them.
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Quick answer: choose rigid mineral wool (Rockwool/Rockboard) for slightly denser, easier-to-handle slabs that hold their shape; choose rigid fibreglass (Owens Corning 703/705) if it’s cheaper or easier to source where you are. Both belong inside a fabric-wrapped frame, as covered in how to build acoustic panels.
What These Materials Actually Are
Both are porous, fibrous insulation products repurposed for acoustics because they absorb broadband sound energy well:
- Mineral wool (Rockwool): spun from molten rock/slag. Sold as rigid boards (e.g. Rockboard / Safe’n’Sound type slabs). Generally fairly dense and firm.
- Rigid fibreglass (Owens Corning 703/705): spun glass fibre pressed into rigid boards. The 703/705 designations indicate different densities, with 705 being denser than 703.
Crucially, these are not the same as the fluffy, low-density loft insulation batts. For panels you want the rigid, higher-density boards. The fluffy stuff is designed for thermal insulation between joists and is too floppy and low-density to make a clean, effective acoustic panel. When people say “Rockwool” in a studio context they almost always mean the rigid slab products, not loft roll.
Why Both Beat Foam
Before comparing the two against each other, it’s worth being clear why either beats the foam tiles many beginners reach for first. Acoustic foam is light and shallow, so it only absorbs high frequencies and a little of the upper mids. It does nothing meaningful for the low mids or bass that cause the worst problems in small rooms. Rigid mineral wool and fibreglass are denser and used much thicker, so they absorb far further down the spectrum. And the egg-carton trick is a pure myth — egg cartons have no useful absorption at any frequency and aren’t fire-safe either. So whichever of the two you pick here, you’re already making the right call. The myth-busting continues in acoustic treatment for home studios.
Absorption Performance
At the densities and thicknesses used for studio panels, Rockwool and rigid fibreglass perform very similarly across the mid and high range. Both have strong absorption coefficients when built thick. What matters far more than the brand is:
- Thickness: 50 mm for mids/highs, 100 mm for lower reach.
- Air gap: mounting off the wall pushes absorption lower with either material.
- Density in a sensible window: very low density (loft batt) absorbs less effectively in panels; extremely high density starts reflecting more. The standard rigid boards sit in the right range.
In short, don’t agonise over which scatters or absorbs “better” — at panel densities they’re close enough that placement and thickness decide your results. See how much acoustic treatment do you need for getting the quantity right.
If you’ve seen published absorption-coefficient charts for 703 and various Rockboard products, you’ll notice the figures track each other closely across the audible range, with small differences that depend on density and how the test was set up (mounting and air gap change the numbers significantly). The honest takeaway is that those small published differences are swamped in a real room by how thick your panel is and where you put it. A 100 mm panel of either material on an air gap, placed at a first reflection point, will beat a thinner panel of the “better” material stuck flat to the wall every time.
Density and Bass
For thick corner bass traps, a moderately dense rigid board (either material) works well. There’s a common myth that “denser is always better” — beyond a point, higher density can actually reduce low-frequency absorption because the material becomes too airflow-resistant. For bass, depth and an air cavity matter more than chasing maximum density, which is why a straddled corner trap beats a thin dense slab. More on building those in how to build a bass trap.
Handling, Safety and Mess
This is where many DIYers form a preference:
- Rockwool tends to be firmer and crumbles less, so it’s a bit cleaner to cut and holds its edges in a frame nicely.
- Fibreglass (703/705) is rigid too but the glass fibres can feel itchier to some people.
Either way, wear a mask, gloves, long sleeves and eye protection when cutting, and work in a ventilated area. Once fully wrapped in fabric, both are clean and safe to live with. Always seal panels properly so nothing sheds.
Two practical handling notes worth knowing before you buy. First, mineral wool is generally heavier than fibreglass of the same size, which matters when you’re hanging large panels or floor-to-ceiling corner traps — heavier panels need solid fixings into studs or joists, never bare drywall. Second, both materials hold their shape well enough to friction-fit inside a frame without sagging over time, unlike soft batts, so your panels stay flat and tidy for years. If you’re building tall corner traps as in how to build a bass trap, the extra weight of stacked slabs is the main thing to plan around.
Fire Safety and Smell
Both rigid mineral wool and rigid fibreglass are non-combustible mineral products, which is one more reason they’re preferable to foam and to myths like egg cartons. That’s a genuine safety advantage in a room full of electronics. Some boards have a faint binder smell when new; airing them out before wrapping, and sealing them fully in fabric, deals with that. As always, confirm the specific product’s own safety information rather than assuming, since formulations vary between manufacturers and regions.
Cost and Availability
Prices and stock vary a lot by region, so the practical advice is: buy whichever rigid board you can get locally without paying for shipping a heavy, bulky product across the country. In some regions Rockwool-type slabs are easiest to find at building merchants; elsewhere Owens Corning 703 is the standard studio choice. Both are far cheaper per unit of absorption than commercial panels from GIK Acoustics, ATS, Primacoustic or Auralex — those mainly buy you finish and convenience.
Which Should You Choose?
| If you want… | Pick |
|---|---|
| Firm slabs that cut cleanly and hold shape | Rockwool / mineral wool |
| Whatever’s cheapest and locally stocked | Either — performance is comparable |
| A proven studio standard board | Owens Corning 703 |
| Maximum bass control | Either, built thick with an air gap |
Honestly, both are correct answers. Pick based on price, availability and which is less itchy for you to work with, then put your energy into thickness and placement. Build them with how to build acoustic panels and position them per where to place acoustic panels.
Common Mistakes to Avoid
Whichever material you choose, the same handful of errors trip people up:
- Going too thin. A 25 mm board barely outperforms foam. Use 50 mm minimum, 100 mm for serious mid-bass and corner work.
- Mounting flat with no air gap. You’re leaving easy low-frequency absorption on the table. Add a gap behind the panel.
- Using non-breathable fabric. If air can’t pass through the cover, high frequencies reflect off it and never reach the absorber.
- Buying loft roll by mistake. Make sure you’re getting the rigid board product, not soft thermal batts.
- Ignoring the corners. No amount of flat wall panelling fixes bass; that’s a job for thick corner traps regardless of material.
Get those right and the Rockwool-versus-fibreglass question becomes almost academic. Round out your plan with how much acoustic treatment do you need.
Frequently Asked Questions
Is Rockwool or fiberglass better for acoustic panels?
Acoustically they’re very close at the densities used for panels. Rockwool is often firmer and easier to handle; rigid fibreglass like Owens Corning 703 is the long-standing studio standard. Choose on price, availability and handling.
Can I use cheap loft insulation instead?
Low-density fluffy loft batts absorb less effectively and are floppy to work with. Use the rigid, higher-density boards (Rockboard, 703/705) designed to hold their shape for proper panel performance.
Is mineral wool or fiberglass safe to have in a studio?
Yes, once fully wrapped in breathable fabric so no fibres shed. Wear a mask, gloves and eye protection while cutting and assembling, and work in a ventilated space.
