Non-combustible
Made from stone, rockwool doesn't burn and withstands very high temperatures — the reason it's used in fire-rated walls and around heat sources.
Rockwool — the stone-based form of mineral wool — is the premium pick when fire resistance, soundproofing, and moisture resistance matter. Dense, non-combustible, and higher R-value per inch than fiberglass.
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What It Is
Rockwool is a dense insulation spun from molten stone and slag into fibers — it's the rock-based form of what's also called mineral wool, so the two names refer to the same family of material. Because it's made from natural rock and recycled slag (a steel-production byproduct), it's also an eco-friendly, sustainable choice. What sets it apart from ordinary batts is what that stone origin gives it: it's non-combustible, it deadens sound and vibration better than lighter insulation, and it shrugs off water rather than soaking it up.
Those properties make it the premium choice for specific jobs — fire-rated assemblies, quiet interior walls, and moisture-prone spots — where a standard fiberglass batt or cellulose isn't the best fit. It costs more than those, so it's about using it where its strengths actually pay off, which is what we help you decide.
Why Rockwool
The properties that make rockwool worth the premium in the right spots — all inherent to the material.
Made from stone, rockwool doesn't burn and withstands very high temperatures — the reason it's used in fire-rated walls and around heat sources.
Its density makes it one of the best insulations for blocking noise — ideal for interior walls, media rooms, and shared walls.
Rockwool sheds water rather than absorbing it, and dries out without losing performance — a real advantage in damp-prone areas.
At roughly R-4 per inch, rockwool insulates a bit better per inch than standard fiberglass, so you get more from the same cavity depth.
Semi-rigid batts hold their shape and friction-fit tightly between studs and joists, so they don't sag or slump over time.
Because it's mineral-based and doesn't hold moisture, rockwool resists mold, and it offers no food value to pests.
Is It Right for You?
Rockwool is a premium material best used where its strengths matter. These are the situations it's made for.
Fire safety is a priority
Around a furnace, chimney, or between living units, rockwool's non-combustible fire resistance is exactly what you want.
You want quiet
For a media room, home office, bedroom wall, or a unit shared with neighbors, rockwool's sound dampening is a standout.
A moisture-prone space
In areas that see damp, rockwool's water resistance means it keeps performing where fiberglass would sag and lose R-value.
You want more R per inch
In a shallow cavity where you can't add depth, rockwool's higher R-value per inch squeezes more performance out of the space.
Interior sound walls
Insulating interior walls purely for quiet — not temperature — is a classic rockwool job thanks to its acoustic density.
Rim joists & exposed framing
Its rigidity and fire/moisture resistance make rockwool a strong pick for rim joists and other exposed, accessible framing.
How We Work
Rockwool performs when it's the right material for the job and fitted snugly. Here's how we handle every install.
We inspect the space and your goals — fire, sound, moisture, or R-value — and confirm whether rockwool is the right call or a lighter material would do.
We recommend the right rockwool batt or board and thickness to hit the fire, acoustic, or thermal target for your space.
If existing insulation is old, compressed, or contaminated, we remove and haul it away so the rockwool sits on a clean surface.
We cut the semi-rigid batts to size and friction-fit them snugly around studs, wiring, and obstructions — no gaps, no compression.
We confirm full, even coverage, clean up completely, and walk you through the finished job.

Why Attic Pros
For over 13 years, Bay Area homeowners and businesses have trusted us for insulation — because we recommend the right material for the job (not just the priciest), install it properly, and stand behind our work.
Real Customers, Real Results
These guys are awesome. Super clear comms to schedule, then received an extremely thorough consultation. We eventually decided to go with them as other shops in the area didn't communicate as well as Attic Pros.
Tom from Attic Pros was great to work with! He was friendly, professional, and thorough during the inspection. He clearly explained everything he found and answered all of my questions. The whole process was straightforward. Thank you, Tom!
Finding out we had a rodent infestation for the first time was incredibly stressful, but Attic Pros made the entire process so much easier! Jeremy was very knowledgeable when help preparing the estimate and the work that needed to be done. Their team that came to perform the work—Nico Otten, Juan Rodriguez, and Antonio Lopez—were amazing from start to finish. Communication was fantastic right from the beginning. The crew was super fast, highly efficient, and left everything very clean after sanitizing our attic, crawl space, and garage. They definitely gave us total peace of mind. They were also able to finish in one day!!
Our small cottage has a very narrow attic entrance. Denis from Attic Pros was willing to try and was able to enter to clean, vacuum, and replace the old insulation. Very professional, access areas were well shielded and protected. Powerful vacuum and clean up well after themselves.
Tom Best came to our house to give us an estimate on new insulation. He was on time, very thorough and provided a detailed very reasonable estimate within an hour of his visit. What more could you want?
Samim great service my attic was left very clean meticulous. I am so happy with the work that him and his team did great service. I recommend them highly. I would give them a 10 if I could.
QUESTIONS, ANSWERED
Straight answers to the questions people actually ask about rockwool insulation — fire, sound, moisture, and how it compares. Still weighing your options? Our team is happy to help.
Talk to our team — we're here to help.
(800) 543-0382Explore More
Ready when you are
Tell us about your project — fire, sound, moisture, or thermal — and we'll assess the space, recommend whether rockwool is the right fit, and give you a clear, no-pressure estimate.
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