Downside to laminate floors with attached pad?

[kcrummett]

Hey guys, I've read quite a bit on this forum about floor surfaces and I've also talked about this to a few friends who have built multiple studio's in the past… Are there negative effects to using laminate flooring that has an underlayment/padding beneath it? One person I've been discussing the studio construction with was very adamant on not using any kind of hard flooring with a pad under it because it creates a high q tuned bass trap. He sited a guy on Gearslutz who did this while building a multi-million dollar facility and had to tear out all of his hardwoods then reinstall them by glueing them directly to the concrete. He told me that if I go with any kind of hard flooring it should be glued directly to the concrete with noting between.

So in short(ish) list form…

1. Is there truth to the High Q Bass Trap theory? And does it apply to laminate with attached underlayment?

2. I don't want the floors to be just concrete. I didn't like the aesthetic so I did a a garage floor epoxy and it's already chipping from dropped drum hardware, kick drums being set spurs down and bass cabs being drug across the room. I'm done with it. I hate having a floor that I have to be "careful" with. If I want to record a cymbal dropping on to a glass bottle, I just want to do it with out worrying about having to redo the entire floor afterward.

3. Real hardwood flooring isn't in my budget and gluing laminate flooring directly to the concrete seems like a recipe for cracking and possible moisture problems. Thought on this?

4. I installed flooring like this in the previous studio I was renting and liked it's ease of use, durability and over all look for the price. But the studio I'm working in now is on my own property and will mostly likely be home base for me for many years to come. So I want to do this right. My previous, rented studio did have some serious, extreme EQ problems, but blaming it on the flooring would be an uneducated accusation on my behalf. There was a lot wrong with the design and construction of that place.

Thanks in advance for your help!

[Soundman2020]

Hi "kcrummett". Welcome!

Please read the forum rules for posting (click here). You seem to be missing a couple of things!

Are there negative effects to using laminate flooring that has an underlayment/padding beneath it?

To be very honest, I don't know how else you would possibly lay laminate flooring, since that is what the manufacturers recommend! I may be wrong, but I have never seen any laminate flooring that is designed to be laid without any underlay.

But that's a practical issue: let's look at the acoustic issue...

One person I've been discussing the studio construction with was very adamant on not using any kind of hard flooring with a pad under it because it creates a high q tuned bass trap

Maybe you could ask him to cite the math that he used to arrive at that conclusion. In order to be high-Q, it would have to be very tightly tuned. I'm not aware of any way of doing that with a thin, light-weight leaf over an even thinner slightly resilient spring. I'd like to see the equation that he used to come to that conclusion.

He sited a guy on Gearslutz who did this while building a multi-million dollar facility and had to tear out all of his hardwoods then reinstall them by glueing them directly to the concrete.

Do you have the link to that thread on Gearslutz? There's a few pretty good acousticians over there, so I'd like to see what they had to say about the situation.

He told me that if I go with any kind of hard flooring it should be glued directly to the concrete with noting between.

If you did that with common laminate flooring, it would soon crack, probably. It is designed to flex on top of a resilient layer. It is not designed to be glued to an uneven surface. With most building products, it is pretty much always a good idea to use it the way the manufacturer intended, rather than the way recommended by "some guy who told me that he once heard someone else say that....."

Is there truth to the High Q Bass Trap theory?

I very, very much doubt that. In order to have resonance at very low frequencies, you would need a high mass for the leaf (flooring), and low resilience for the spring (underlay).

Here is the actual equation that describes resonance:

f = ( 1/(2 * PI) ) * SQRT (k/m)

Where:
f is the resonant frequency
k is the spring constant (resilience or stiffness)
m is the mass of the moving part.

Another way of thinking of the term "k/m" is "elasticity / inertia". This implies that as mass INCREASES the frequency goes DOWN, and as elasticity DECREASES the frequency goes down. So in order to have a system that resonates at low frequency, you need high mass and low resilience. Laminate flooring does not have high mass. Underlay does not have low resilience.

I think your conclusion is obvious from the equation...

I modeled this situation quickly, making some wild assumptions about how laminate flooring behaves and how underlay behaves. This is the prediction:

laminate-flooring-resonance-graph.jpg

For that, I assumed that laminate flooring behaves something like a limp membrane (probably not true, but it's a starting point), and that underlay behaves something like a porous absorber with acoustic impedance similar to medium density semi-rigid compressed fiberglass insulation.

As you can see, the resonant frequency is WAY beyond anything even remotely resembling bass. It's around 900 Hz. Slap bang in the middle of the mid range.

There's a high Q, yes, but that's only because the above is a very simple model, and does not take into account damping. The entire surface area of laminate flooring is extremely well damped by the underlay (which is one of the reasons the underlay is there!). So taking that into account, here's what we get:

laminate-flooring-resonance-graph-2.jpg

In this case, I simulated your floor as being one large slotted panel with no slots, with the panel being 8mm thick, over 2mm of underlay.

I'd say the Q is r-a-t-h-e-r- broad! And the resonance is basically non-existant.

Yes, I'll be the first to admit that my methods for modeling this are very much not valid, and my assumptions are pretty wild, but in my defense I did test out a whole range of assumptions in each case, some more wild, some less wild, and they all gave similar results. In reality, laminate flooring is neither a limp membrane, and nor is it a slotted panel with no slots: it lies somewhere in between.

However, no matter which way you look at it, a thin layer of light-weight mass over a thin underlay, is not going to be a massive bass trap.

Sad to say, your friend is very much mistaken.

I suspect that he confused "laminate floor" with "floating floor". It's an easy mistake to make, since in some countries, laminate flooring is indeed called "floating floor", even though it is NOT floating floor! The name is wrong, but that does not stop the manufacturers from using it!

I suspect that your friend is describing an incorrectly built floating floor (not laminate floor), where someone put down a wooden frame on rubber pads, put some plywood on top, then put laminate flooring on top of the plywood (with underlay). Yes, in that situation, most definitely you could create a resonant system that could wreak havoc on both your isolation and also your room acoustics. It could, indeed, create a tuned system with relatively high Q, down in the bass range.

Someone who did not understand the problem might well think that it was the laminate flooring causing the problem but in reality it is the resonant cavity under the plywood.

3. Real hardwood flooring isn't in my budget

It isn't in most people's budget, either! It's expensive stuff. Nice if you have deep pockets, but not necessary in a studio.

and gluing laminate flooring directly to the concrete seems like a recipe for cracking and possible moisture problems.

Yep! Very much so. Dead right.

4. I installed flooring like this in the previous studio I was renting and liked it's ease of use, durability and over all look for the price.

And you did good there! Do it again.

My previous, rented studio did have some serious, extreme EQ problems, but blaming it on the flooring would be an uneducated accusation on my behalf.

I would agree with that. Laminate flooring laid on concrete is very, very unlikely to be causing frequency response problems in a room. It is far, vastly, incredibly more likely that the room was just poorly designed, poorly laid out, poorly treated, and poorly tuned. Those are the vast majority of all frequency response issues in project studios. If I had to guess, I'd make up a brand new statistic, and say that 99.973% of all frequency response problems in studios are NOT caused by properly installed laminate flooring on underlay over a concrete slab...

There was a lot wrong with the design and construction of that place.

And now is your opportunity to fix it! As you mentioned, this is going to be your own personal place, and it has to be better than good, so it needs to be designed and built correctly from the start. If you post your design here, I'd be glad to take a look at it for you, and tear it apart to see what's wrong with it, and how it can be fixed. That sort of is what the forum is here for!

But to answer your basic question here: just put down some good quality laminate flooring, on good quality underlay, directly on top of your concrete slab, and you'll be fine. That will NOT be creating a highly tuned bass monster that will growl at you every time you want to record or mix. There is no cause for concern about that. And if your laminate flooring comes with underlay attached, that's fine too. Even better, in fact since you can be certain that the underlay is very well matched to the flooring!

There might be other issues in the room that cause you massive bass issues, but it won't be your laminate floor.


- Stuart -

[realdoyle]

Soundman2020,

I just wanted to say this was one of the best replies i've seen on any forum. You gave credence in his friends claims and then backed up your debunking reply with the math. Thank you for taking the time to do this and for all your contributions on this site. You are helping a lot of people (including myself) accomplish goals that they wouldn't be able to otherwise.

-Doyle

[Soundman2020]

I just wanted to say this was one of the best replies i've seen on any forum. ... Thank you for taking the time to do this and for all your contributions on this site. You are helping a lot of people (including myself) accomplish goals that they wouldn't be able to otherwise.

Thanks very much for the kind words, Doyle! It's comments like yours that make all the effort worthwhile. Very much appreciated!


- Stuart -

[ABitAnalog]

For my second post, I was expecting to have a bunch of questions specific to my situation. However, your reply above really "put me some knowledge" concerning resonances, etc.

[kcrummett]

Stuart!! I never thanked you for your reply. It was exactly the answer I was looking for. My wife's water broke as I was reading your reply, we had a healthy baby 22ish hours later and I immediately fell in to one of the busiest schedules of my life with producing and engineering. I did find time to install most of the flooring, it looks great and I feel like my live room sounds better than it did with the concrete floor.

So my next endeavor is finishing the acoustics part of the build in my control room. I've just been working out of there with a large cloud I built above the mix position and Real Trap panels on the side and back walls, but I want all the acoustics to be permanent, pro looking and most of all, correct. I'm making a SketchUp of the room and would love some advice on how to go about this. Before I get too deep in to it, should I start a new thread for this? Or continue the conversation in this thread? Thanks!

[Soundman2020]

My wife's water broke as I was reading your reply, we had a healthy baby 22ish hours later and I immediately fell in to one of the busiest schedules of my life

Wow! Big, major congratulations to you and your wife! And I sure do understand the "busiest schedule of your life"! I have two kids of my own, so I've "been there and done that". They are both grown, now (one is a doctor, the other in university), so I can tell you from experience that from here on the "busy schedule" thing only gets worse! OK, so it's not so bad, but I though you could use some encouragement...

I did find time to install most of the flooring, it looks great and I feel like my live room sounds better than it did with the concrete floor.

Excellent! And I'm betting that it's not a "high Q bass trap" either!

I've just been working out of there with a large cloud I built above the mix position and Real Trap panels on the side and back walls, but I want all the acoustics to be permanent, pro looking and most of all, correct.

Cool! You are in the right place, for sure, right here on the forum.

I'm making a SketchUp of the room and would love some advice on how to go about this. Before I get too deep in to it, should I start a new thread for this? Or continue the conversation in this thread? Thanks!

First, check those forum rules again! There's a lot of info in there on how to start a thread about a studio project.

It would probably be better to start a new thread in your case, and in the very first post put a link back to this thread, so you (and others) can find it if you ever need to reference it again in the future. In your first post on that thread, put in as much detail as you can about your studio, following the hints in the forum rules... then ask the questions you need to ask to get started! I would also suggest that you do some testing with the REW acoustic software package, so you might as well download that, calibrate it, and start learning how to use as well.


- Stuart -