floor underlayment vs sheetblock etc

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floid
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floor underlayment vs sheetblock etc

Post by floid » Sat Feb 15, 2014 5:09 pm

This week at work I've been installing a floating hardwood floor. The underlayment we're using is just standard issue stuff you can find at any hardware store, and looks more or less like a 1/8" layer of compacted dryer lint with a plastic facing. It claims to have an STC rating of 66 and costs $50 for 100 sq ft. Auralex sheetblok, mutex, and similar products typically claim an STC rating of 30 or so and cost 5 to 10 times as much.
What am I missing here?
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Post by JWL » Sat Feb 15, 2014 5:44 pm

Hi, please accept this post as an attempt to be helpful and not a hardass. :-D

I'd suggest picking up Rod Gervais' book, Home Recording Studio: Build It Like The Pros. It has detailed discussions on floating floors, and on why in most cases it may not make sense to float the floor.

Another good resource will be www.soundproofingcompany.com -- they have great products and articles on their website.

Another question is, does what you describe constitute a floating floor? It doesn't sound like it to me, but I'd need to see more details about the construction you have going on to know for sure.

My advice is to SLOW DOWN and do some research here, because it's easier (and cheaper) to build it correctly the first time than to build it incorrectly and have to "fix" it later, undoing much of what you've worked so hard to do.

So yeah. Check Rods book. Post more details, like a picture or a diagram of how the floors are constructed, how they join to the walls, etc. Also you haven't stated what your goals are -- how much isolation do you need?
Last edited by JWL on Sat Feb 15, 2014 7:36 pm, edited 1 time in total.

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Post by floid » Sat Feb 15, 2014 7:25 pm

sorry, perhaps i wasn't being clear: my day job is general construction. the floor i'm working on is not designed towards any acoustical goal, it's just a standard issue residential engineered hardwood floor, 'floated' for purposes of expansion/contraction rather than isolation. i noticed the STC rating on the package of underlayment, and it led to my wondering how this stuff might compare to the various limp mass vinyl products on the market if used in, say, a wall assembly (perhaps drywall-underlayment-drywall). i kind of figured the STC rating didn't tell the whole story, but these other products do often mention things like 'class leading STC of 30.' i do have Gervais' book, btw, as well as a few others. they don't discuss these new products though. perhaps you could describe their proper applications, and why any old sheet of stuff won't work as a substitute?
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Post by JWL » Sat Feb 15, 2014 7:39 pm

Ah, sorry for misreading. Still a bit loopy from a nasty flu this week. ;-)

I've only worked with the normal underlayment, so I can't comment on the other brands.

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Post by norton » Sun Feb 16, 2014 7:27 am

In lab testing for floor underlayments we found that there was no major benefit between any of the "acoustic" solutions. In fact, none of the commercially available floor underlayments were really any better or worse than the other.

Some sort of cushioning layer is a great idea, but really it's one of those anything is better than nothing kind of deals.

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Post by norton » Sun Feb 16, 2014 7:27 am

In lab testing for floor underlayments we found that there was no major benefit between any of the "acoustic" solutions. In fact, none of the commercially available floor underlayments were really any better or worse than the other.

Some sort of cushioning layer is a great idea, but really it's one of those anything is better than nothing kind of deals.

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Post by rushofblood » Sat Mar 01, 2014 12:31 pm

I get what you're askin, Floid. I'm wondering the same.

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Post by floid » Sat Mar 01, 2014 3:32 pm

norton wrote:In lab testing... none of the commercially available floor underlayments were really any better or worse than the other...
it's one of those anything is better than nothing kind of deals.

so do i understand this to include a family of products that ranges all the way from 'blue hawk' floating floor underlayment to auralex sheetblok?
i get that 'designed for professional acoustic applications' often commands a premium, for reasons that may range in legitimacy. but one thousand percent seems a rather ridiculous difference in price for 'the acoustically targeted solution that's better than nothing.'
gotta admit i've found the idea of a roll of stuff 1/8th inch thick doing any serious soundproofing kind of ridiculous right from the beginning. then again, greenglue seems pretty tried and tested...
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Post by norton » Sun Mar 02, 2014 7:36 am

Physics is weird science. Gg works...and nothing else on the market (other than a very similar formula) is a suitable substitute.

The underlayment testing I was involved with was through the looking glass absurdly thorough.

The only real acoustic benefit you will get from an underlayment will be from footfalls and tapping noises. None of the "acoustic" underlayments will significantly alter the stc rating of your floor/ceiling. But a cushioning layer will help stop the tap tap noises from getting through.

And... From what we found, the differences between various underlayments were very slight.

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Post by Ric Vaughan » Wed Oct 08, 2014 11:41 am

please remember STC rating die at 125hz
that really doesnt apply to us in the music world.
i have forund a product i use both here and in europe call Roxull Strong Plate.
It high density mineral wool used to insulate under poured concrete.
a lyer of that, the 5/4" T&G ply and then flooring of choice works great.
i have even used this and a platform to frame the rooms on.
literally the room is floating.
in europe its call rockwool Tungplate..
it works.

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Re: floor underlayment vs sheetblock etc

Post by Waltz Mastering » Sat Oct 11, 2014 9:22 am

floid wrote:This week at work I've been installing a floating hardwood floor. The underlayment we're using is just standard issue stuff you can find at any hardware store, and looks more or less like a 1/8" layer of compacted dryer lint with a plastic facing. It claims to have an STC rating of 66 and costs $50 for 100 sq ft. Auralex sheetblok, mutex, and similar products typically claim an STC rating of 30 or so and cost 5 to 10 times as much.
What am I missing here?
It's highly doubtful that the standard compact underlayment has the rating it claims unless they are describing when it's used in conjunction with other materials.

You can get MLV at marine supply stores at about a quarter of price than you'd find at Auralex and it does work good in some applications when space is a concern.

Here's some other info on floating floors. gl

http://prorecordingworkshop.lefora.com/ ... DlWk-fxieU

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Post by norton » Sun Oct 12, 2014 8:35 am

Probably a dead horse thread....

Any underlayment is essentially as good as another. In the floor/ceiling assembly the key is shock absorption. Which is fairly difficult to achieve to a great degree, but easy to achieve to a certain result.

Cardboard, insulation, carpet, pergo underlayment, mlv.... They are all going to perform essentially the same as an underlayment....in stopping impact noise transmission. So use what you want, but keep the price to performance ratio in mind.

Now mlv does have a shit ton more mass than cardboard or floor underlayment....and it may add some stc benefit to your assembly a point or two perhaps. But it will soften physical transmission (impact) as good as, and not appreciably better than any other floor underlayment.

The floor/ceiling assembly is the trickiest beast in sound isolation. Filling the cavity with insulation, using some sort of decoupled Sheetrock assembly for the ceiling below, with green glue and covering the floor above with carpet is about as good as you can get.

You can go crazy and green glue and double layer the subfloor above but the law of diminishing returns is in full force

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