crazy carpet floor float idea?

ollie wrubel · Post by **ollie wrubel** » Tue Jan 11, 2005 12:30 pm

Hi all,

It's the guy with the church again. Trying to figure a way to float the floor without going completely broke. (2,500 square feet worth) It's got a thick pile wall to wall carpet with a heavy rubber backing that I'm going to have to rip up and discard. Then I thought - hmmm, what if I put a couple of layers of plywood right down on the carpet? (I've attached a bit of a drawing) Any way of figuring out how compressed the rubber/fibers would be and what frequencies might be best isolated (I'm most worried about low frequency type stuff from the street) Any other dangers, like, would it feel squishy to walk on?

When you're all done laughing, maybe you could give me your thoughts.

Ollie

knightfly · Post by **knightfly** » Wed Jan 12, 2005 1:57 am

Main problem with that is mold, dust mites, etc - gives 'em too good a place to hide. this will also rot the material placed over the carpet. Some have floated floors over rockwool, but I've not seen a way to predict the squish... Steve

ollie wrubel · Post by **ollie wrubel** » Wed Jan 12, 2005 9:21 am

Thanks Steve,

Yeah, I figured there'd be some kind of trouble but of course, I was hoping someone would say it was the greatest idea ever. Oh well.

-Ollie

genericperson · Post by **genericperson** » Wed Jan 12, 2005 2:16 pm

have you looked into Auralex U-boats?

knightfly · Post by **knightfly** » Thu Jan 13, 2005 10:55 am

The U-boats are a good choice for simple; those, as well as any other "puck" approach, need to be carefully set up so as to transfer the floated floor weight evenly to the joists below, where a full sheet approach would automatically do that -

Speaking of which, if you're planning a floated floor over anything but ground level concrete slab, we need to talk about this a LOT... Steve

ollie wrubel · Post by **ollie wrubel** » Fri Jan 14, 2005 2:23 pm

Well, yes, the second floor of the church is hardwood floors over heavy joists supported by posts on 12 foot centers. As I learn more, and do the math on materials, I'm begining to doubt that I can float the whole 2500 square feet, but I do want to get as much isolation between the control room, Iso spaces, and main studio as I can. I'd love to hear your thoughts, Steve.

-Ollie

knightfly · Post by **knightfly** » Fri Jan 14, 2005 6:26 pm

"hardwood floors over heavy joists supported by posts on 12 foot centers" - this leaves a bunch of information to the imagination - like how far apart the joists are, what is "heavy", are the posts on 12' centers or are the joists on 12' centers and SUPPORTED by posts, how thick is the hardwood, is there anything on the UNDERside of the joists or are they open, etc... - do you by any chance have pix or a drawing available to better illustrate some of this?

Just as a general rule, if you're concerned with YOUR noise getting to the public, the first room I'd float would be any that will be used to track drums or bass (unless you'll always be DI'ing the bass) - the second room would be the CR; those two will let you set mics on the kit without having to hear the kit ALSO through the building; that way, you can actually tell if you have a phasing problem with mics on overheads canceling out one or another part of the kit, etc - you can also, with those two rooms floated, "crank it for effect" without worring about pissy neighbors.

If, however, you're more worried about OUTSIDE sound bothering the recordings, then the first room to float would STILL be the drum room, the second would be the one you do the most sensitive recordings in, likely the main tracking room; and the third would be the CR, again so you can set mics by speaker instead of by "wall" sound.

Ideally, each room would be floated, using several inches of concrete over custom in-slab jacks, with adequate load bearing in the main floor to support the load.

If you intend to go THAT route, I'd like a new Yamaha DM2000 out of your petty cash; you'd never miss the $$...

All seriousness aside, from what I'm hearing the FIRST thing you need to do is hire a good structural engineer, and tell him you want to put 5" of concrete on that ENTIRE upper floor, supported at point sources on 24" centers resting on compressed fiberglass pucks, and see how hard he laughs...

Then tell him, "no, really; whats' it going to take?" and see if he pukes, runs, or otherwise does something to shake your confidence - that'll tell you whether your second floor is strong enough for serious isolation building or not - by using 5" of concrete as a figure, it should allow you to actually use 3-1/2" concrete floors and have leeway for floating the walls and possibly ceilngs on your floor.

That's kinda my thoughts so far... Steve

z60611 · Post by **z60611** » Fri Jan 14, 2005 6:50 pm

knightfly:

no, really; whats' it going to take

If money were no object, one could, from the bedrock up,
a) footings into the earth through the basement concrete slab
b) concrete+rebar columns, at least 4, each perhaps a foot or more in diameter, rising through the basement, and any intermediate floors. -- some sort of latteral reinforcement may also be required if it's possible to push the columns over.
c) a 5" concrete floor (completely held up by the columns, possibly cantilevered)
d) Kinetics springs
e) one or more 5" concrete floor(s) - these are floated! ('more' to decouple each sound room from each other)
f) room-in-a-room(s) built on the concrete floor (e)

Obviously if one were going to do something like this, one would absolutely need an acoustical engineer and a structural engineer and a building permit.

(Might be cheaper to rip the building down and start over.)

knightfly · Post by **knightfly** » Fri Jan 14, 2005 9:58 pm

I hear Galaxy is for sale, but you'd have to move it from Eric's back yard; might be kinda spendy...

ollie wrubel · Post by **ollie wrubel** » Sat Jan 15, 2005 1:50 am

Hey, you guys are a funny bunch with your 5" of concrete on cantilevered steel.

The church was built in 1800, (so I won't be tearing it down - it's a bit of an icon in the town and a fascinationg place, as well) and I won't take ownership until next week, so construction details are a little sketchy at the moment - plus everything is covered up by thick layers of plaster and lath. The sanctuary is on the second floor, and obviously designed to hold up a lot of people (200?) but I doubt we can add 5" of concrete. My main concern is to knock down the traffic noise from outside as much as is practical. I figure maybe I can build one Iso space that's better isolated than the main studio that can be used for things like vocals or acoustic guitar.

I'll provide drawings soon, (and photos) but what I'm trying to do here is get a sense of what can and cannot be done. For instance, in general is it a waste of time and money to put the usual arangement of 2 by's on neoprene pads with a couple layers of plywood over my wood frame (not a concrete slab) second floor? Will it be better than nothing, worse than nothing? Is there a better approach? That kind of thing.

Since I'm at the pencil and paper stage of design, this is the time to make big changes. And yes, I'll run these ideas by a structural engineer long before any hammering begins.

Thanks all, Ollie

knightfly · Post by **knightfly** » Sat Jan 15, 2005 2:06 pm

Any floated floor, other than one that's floated over an even layer of compressible material (like rockwool) will exert POINT loading on the under-floor; before you can decide this question, you MUST know what is already there. PRECISELY what, and precisely WHERE. Without this knowledge, you're asking for death.

For a wood framed floor to support a floated floor, the floating pucks MUST be centered over the existing joists; they MUST be spaced close enough NOT to put all the weight on one section of existing joist; and the existing floor MUST be able to support the extra weight, in the case of a fully floated room, of ALL the new building materials AND the occupancy AND the equipment, or someone may die.

If you go with lighter materials in order to stay within the support capabilities of the existing floor, then to compensate for the higher m-a-m frequency this will cause, you can use deeper floated joists; this will widen the air gap (completely filled with rockwool, or boomy; your choice) - a wider air gap, with no other changes, will lower m-a-m frequency (a GOOD thing) - ideally, especially for drums and bass, the m-a-m frequency should be an octave or more below audible; IOW, 10 hZ or less. This isn't easy without using heavy mass, but can be compensated for somewhat by thicker joists.

BTW, unless you're planning on moving out in 10 years or less, I'd go with EPDM instead of Neoprene - more expensive, but more like 25 year life expectancy instead of 10 -

Some background -

http://www.earsc.com/HOME/engineering/T ... asp?SID=61

note the yellow and gray graphic about 40% of the way down the page - this is why non-calculated floating floors can be such a crapshoot... Steve

ollie wrubel · Post by **ollie wrubel** » Mon Jan 17, 2005 5:29 am

Ok Steve, I think I get all of that, and I've included a new version of my drawing that shows what I think you've described. Of course, I don't have enough specifics yet (but I will soon) about the existing floor, and I'm hoping you can help with the new mass and distance factors (at which point I can then do the math to figure total weights, and then start the process of figuring the live load limits of the existing structure).

But - seems like this whole thing creates a three leaf problem. Of course I'm mostly trying to isolate the various rooms on this floor from each other, but also I need to reduce vibration from outside traffic, and noise to and from downstairs (client chill space). Should I consider removing the old floor down to the joists? Any other big picture type thoughts?

Thanks - Ollie

ollie wrubel · Post by **ollie wrubel** » Tue Jan 18, 2005 10:26 am

Finally got a little time to do some photography in the church - here's one
of part of the main room. Hope it provides some context and inspiration. More to follow.

By the way, for reference, the top of the window in this shot is 14 feet from the floor. The ceiling height (where the fans are mounted) is 23 feet.
This room is just about 50X50.

Ollie

PS Steve, no need to apologize for being slow - can't imagine where you get all the time for this forum as it is!

knightfly · Post by **knightfly** » Fri Jan 21, 2005 5:54 pm

Man, what a cool looking space; what's it sound like, is there any treatment or is it a 15 second reverb chamber?

Your idea of removing the existing flooring would go a long way toward solving several problems - if you put the new floated joists crossways of the old, and use pucks at the junctions, you would increase your air space tremendously; this would go a long ways toward lowering m-a-m resonant frequency. then, you could fill the entire space with whatever insulation (other than foam) you can, and have the added benefit of lessening the supported weight on the lower joists. Putting the upper, floated joists crossways will also give support to your upper insulation batts, making sure they stay in better contact with the upper floor surface for damping. Whatever weight you remove with the flooring is that much more that can be in the upper leaf, if still necessary to achieve lower than audible m-a-m frequency... Steve

ollie wrubel · Post by **ollie wrubel** » Sat Jan 22, 2005 12:37 am

The reverb time is very suprising - probably only about 1 sec. The lower flat portion of the ceiling (by the windows) has some kind of acoustical tile that someone added, and of course the carpet, which is very thick, is having a huge effect. My first move will be to pull that up and then see what I've got. I'm sure it will be quite different but I suspect from the shape of the room, still pretty nice.

-Ollie