Should I use stone wool insulation?

On our man cave basement remodel, I used stone wool insulation. If you haven’t used it, the stuff is—at least—a triple threat of quality, speed and (for pros) profit.

Whenever I insulate, I’m looking for three main things: Thermal efficiency, as much sound-deadening as I can get, and for the job to take a little time as possible. I love building stuff, but in the end, I do this for money. Time matters to me. A lot.

Installation

There’s a phrase in insulation: Fluff it, don’t stuff it. Insulation works best when its placed, not crammed. Roxul’s ‘value add’ (I’m pretty sure that means something) is that its placed correctly when its slightly compressed between studs. If it were crown molding, I’d call it ‘snap-fit’.

This means there are no staples or stapling. That’s time saved—and lots of it. No infuriating paper ears of tar paper to rip. No stapler to pound way too close to your thumb (although if you do need a hammer tacker, I like the Bostitch PowerSlam). Just quiet, forward progress. Simply place the 4-foot long batt in the bay and friction does the rest. Each piece goes in quickly. I know I shouldn’t like this this much, but I do.

Then there’s the oddball framing of old houses. Joists, for example are somewhat randomly placed. If the joist bay is a bit wider than 16-inches on center, just cut Roxul to fit and install across the bay instead of parallel. There are limits to this of course, but it’s barely even possible with other products I’ve used.

Cutting

No insulation cuts ‘easily’. They’re all a matrix of criss-crossed, interlaced material. And I was expecting Roxul stone wool—a blend of steel slag actual rock mineral—to be a comedy of errors with me all netted up in my own fury. Then I cut it with the bread knife from my kitchen.

Somewhere between saw and slice, I managed it with surprising ease for both batts and panels. Oh my, hearts a-flutter…you think I’m kidding…

Stuffing

I know what I said before, but the world isn’t a perfect place. Sometimes you’ve got to do what you’ve got to do. In this case, I needed to get some Roxul over 3-feet of HVAC duct in a ceiling. I’m not sure how to put this and I don’t want to give the wrong impression, but the batt has enough…umph I’ll call it, rigidity maybe is a slightly better word…to stay together when it meets some resistance. It was a fight, but I persuaded it 4-feet down 20 joist bays.

It’s also fireproof. So when I need to stuff a gap for fire blocking, I can just rip a hunk of this and jam it in there.

Dust and other stuff

Roxul is not even in the same universe of itchy as other insulation I’ve used. I still wear a mask because particles do get free. What’s even better for clean air is a BuildClean air scrubber, but that’s a different story. A long sleeve shirt helps too.

The Math

So there’s an equation developing in all this. And none of it is an ad. It’s just my experience. Roxul is not just faster to install—it’s waaaay faster to install. In walls and ceilings. It comes in batts and panels. It cuts easier and it has gobs more sound deadening than other insulation.

GOBS (scientific term, look it up) more. It’s not sound proof (most of the sound from one floor to another comes through the framing anyway; sound travels through solids better than air).

So whether it’s my house or my client’s house, I can make more money and deliver a better product using stone wool. After all, I do this to buy food and live inside. Love is just part of the math.

Mark

A licensed contractor, tool expert, wood and outdoor enthusiast, and elite Spartan Race competitor, he writes about home improvement and tools for national magazines and websites, and teaches hands-on clinics for other remodeling professionals. Check out his book, The Carpenter's Notebook.

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