Not building on a concrete slab? questions

[PressPlayRec/Stop]

Hello, I am in the research phase of building my studio. There is a space available locally that I am interested in. The dimensions are 32'x19'x9'. The building is an old industrial building with exposed brick walls, the ceiling is finished? / doesn't have exposed ceiling joists and the floor is an old wooden plank floor on the 3rd floor of this huge building that is basically empty. My plan is to Build two separate rooms within this room, having each one built on a floating subfloor sitting on these Auralex U-boat things with Roxule stuffed in between....etc., you get the idea.

My question is..., Is should weight be a concern when not building on a concrete slab. For all I know this wooden floor could be supported by steel beams underneath or old rotting timber that can't take the weight. Also since its wood and not concrete what might be some possible issues with acoustic energy transmission from the studio floating floor to the wooden plank floor and vice versa?

The space is in a commercial area with lots of businesses and light residential that is a good distance away from where the studio will be so Im not worried about bothering the neighbors, Im more worried about keeping noise out from the street below, these streets are narrow and the buildings are close to them so you can hear it when a car passes by. Also there are some other tenants in the building located on the far other side of the building (this building is as long as the entire block)

Thanks for any replies and Thank you for taking the time to read this.

[Soundman2020]

Hi there "PressPlayRec/Stop", and welcome to the forum!

My plan is to Build two separate rooms within this room, having each one built on a floating subfloor sitting on these Auralex U-boat things with Roxule stuffed in between....etc., you get the idea.

Unfortunately, that's not a good plan, and won't accomplish very much, regardless of whether or not the existing floor is able to take the load.

Here's why:

http://www.johnlsayers.com/phpBB2/viewt ... f=2&t=8173

And also:

http://prorecordingworkshop.lefora.com/ ... n-mistakes

If you want the technical laboratory test background information as to why this is so, then :

http://archive.nrc-cnrc.gc.ca/obj/irc/d ... /ir802.pdf

Basically, to get meaningful isolation from a floated floor, you need considerable mass, as in concrete slab. Putting a thin light-weight membrane over a cavity has another name: musicians refer to that as a "drum head". They like it, because when you impact a drum head with something, it resonates loudly and longly and musically. Drums are great when they are arranged as a kit and played by a musician, but not so great when arranged as a floor that you walk on...

Be that as it may, before you can do anything at all in terms of building, the very thing you have to do is to call in a structural engineer to inspect that floor, and the rest of the building that supports it, then give you his professional opinion regarding how much extra live load and dead load you can safely put on it, and also tell you where and how that load can be applied. Don't do anything at all until you get his signed report. As you pointed out, you don't have a clue if it might be supported on rotting timber or massive steel girders, and until you DO know that, for sure, and with the full technical details, it would very unwise to do anything at all there.

You say it's a big old building, so hopefully the report will be positive and you can start planning, but it wouldn't be a good idea at all to do anything more until you have that.

should weight be a concern when not building on a concrete slab.

Weight should ALWAYS be a concern, even when building on a concrete slab!

Also since its wood and not concrete what might be some possible issues with acoustic energy transmission from the studio floating floor to the wooden plank floor and vice versa?

There are multiple issues there, relating mostly to flanking and resonance. "Flanking" refers to sound energy that moves through structures themselves, bypassing attempts at isolation, and "resonance" refers to a whole bunch of other ways in which sound energy can get across air spaces and be heard in other rooms, either close by or distant.

Just yesterday I mentioned to another forum member that I live a few blocks away from a hospital that has an emergency rescue helicopter ambulance on the roof. When they start that thing up to go fetch some unfortunate person, they leave it idling for several minutes to warm it up. If I am outside in my front yard, or walking in the street, then I can hardly hear the chopper idling. It's a very quiet machine, considering that it is a helicopter. But when I go into certain rooms in my house, the noise is deafening! Because those particular rooms happen to have a natural resonant frequency that perfectly coincides with the frequency of that chopper engine at idle. That's the power of resonance. There's a distance of easily a couple of hundred meters from that helipad to my rooms, and the actual airborne noise in between is very low. But resonance is a bitch.

So you might well have the situation where your rooms could pick up some resonance in the building itself, or transmit the resonance from instruments you are recording into the rest of the building.

That can be dealt with by suitable isolation, yes. But wooden planks on rubber pucks is not "suitable isolation"...

- Stuart -

[PressPlayRec/Stop]

Hello Soundman thanks for the reply and the warm welcome. My two other reasons for considering a floating wooden platform sitting on rubber hockey pucks were that I wouldn't have to nail into the existing wooden floor when framing the walls which the landlord may or may not allow, I'll have to ask. The second reason was cosmetic, the wooden plank floor is pretty beat up and ugly. Maybe I can put down laminate wood flooring over the ugly planks

Thanks for the advice about getting a structural engineer to come in and look at the place first I will certainly do that if I plan on moving forward with this location. Finding out that a floating floor is useless is going to save me time and energy and money in NOT building one. My building plans just got simpler.

If I end up not being able to build something that functions and looks like a proper pro recording studio with a control room and a live room at this location I can still use the space as a one room recording studio and just record hip hop / R&b vocals in my prebuilt isolation booth... But I won't be able to record bands... I want to be able to record full bands in this space but I need to make sure I can minimize the amount of sound getting in from outside and vice versa. Rent is cheap and its a nice space and very close to where I live so...

Having my own studio has been a dream of mine for almost half my life now and I just realized that its not an impossible task, I can do this!

[Soundman2020]

I just realized that its not an impossible task, I can do this!

You sure can! Absolutely! And you very likely can use that space, in one form or another. My bet is that the structural engineer will give a you a green light, and you'll be able to load up that floor considerably. If it's an older building, and still standing, then chances are it has good structure. There's always something you can do to pretty much any space to make it more usable as a studio. The only places that don't have much hope are ones with very low ceilings, round rooms, or very, very small rooms. Yours is none of those.

My two other reasons for considering a floating wooden platform sitting on rubber hockey pucks were that I wouldn't have to nail into the existing wooden floor when framing the walls which the landlord may or may not allow,

Sad to say, that would not work either. I very much doubt you'd get a building permit, or a sign-off from a structural engineer, to build load-bearing walls on top of a flimsy wooden base floated on hockey pucks! That would be fine for a correctly floated concrete slab, assuming that the walls are also correctly done with sway braces and seismic snubbers, but not for a thin, flexible, low-mass platform.

The second reason was cosmetic, the wooden plank floor is pretty beat up and ugly. Maybe I can put down laminate wood flooring over the ugly planks

That one is easier to fix: a layer of semi-rigid insulation, such as OC-703 across the entire floor, then a couple of layers of thick OSB, MDF or plywood sitting on top of that, then the underlay, then the finish laminate flooring. That will give you a smooth, flat, solid, decoupled, damped surface. It's not a true floating floor, and you definitely cannot build stuff on top of it (such as walls), but it would go a long way towards what you need. That's the same principle that drum-risers use, to block the impact noise from getting into the floor, except it is on a larger scale.

Finding out that a floating floor is useless

Maybe you misunderstood what I was saying, and what was in those articles I linked you to. A floating floor is NOT useless! A properly down floating floor is a wonder ful thing, and provides excellent isolation. The issue is that a light-weight wood deck sitting on wooden frame on hockey pucks is not a floated floor! A floated floor is a heavy, massive thing, commonly floated on springs, or at least on properly designed resilient mounts that are tuned to the correct frequency.

I want to be able to record full bands in this space but I need to make sure I can minimize the amount of sound getting in from outside and vice versa.

Very likely that will be possible. But wait for the report from the structural engineer. When you know how much extra load the existing structure can take, the the plan can be more clear. And if it can't take a whole lot more load, there's always the option of beefing up the structure in some way to make it happen, although that would be expensive.

But regardless, there's always something that can be done, in pretty much any space, to make it more usable as as studio.

- Stuart -