Replacing floors ABOVE studio...isolation?

[Willangus]

Hey all,

I looked around on the site, and while there's a lot of info on what to do about the ceiling in a basement studio to help isolation, there's not much on what can be done to the floor above...for obvious reasons, I guess (we studio hounds usually have more control over our ceiling than the floor upstairs). But in this case, we'll be tearing up the floor above the studio and leaving the studio ceiling intact.

Here's the deal--we're in a 2-story split-level house; i.e., the second story is the living area, and the first story is the garage and studio. The studio is ~430 sq ft, and directly under about half of the living area.

Floor upstairs is carpet on a plywood subfloor. Ceiling in the studio is finished drywall. I don't know if there's any insulation between the upstairs floor and the downstairs ceiling (house was built in Atlanta in 1973, if that tells anybody anything). There are a couple of light fixtures in the studio ceiling that are likely leaking some sound, now that I think of it. I had planned to replace these.

The main sonic issue is sound leaking down from above into vocal takes (I record mostly singer/songwriters--no drums). Isolation provided by the carpet has been reasonably good--I can hear some footstep impact and loud conversations, but it's not terrible.
--

Now we're about to put in 3/4" thick wood floors upstairs. My father-in-law is coming down from NYC to Atlanta to help us install them in mid-March. He'll be here for maybe 4 or 5 days.

My question to you all is this: can I maintain (or even increase!) the isolation between the 2nd and 1st story relatively simply (so that it can be done in 4-5 days) and not too terribly expensively (<$800 roughly)? It would be great if the wife could fearlessly walk around and have a normal-level conversation while I'm recording.

Couple of miscellaneous thoughts:

I've learned from this site that wood floor transmits more sound below than carpet, so I know this will be a challenge.

The two ways I'm theorizing to do it are (1) to make the floor layer as massive as possible...i.e. roofing felt or Sheetblok or something between the wood floor and the subfloor, or (2) to float the wood floor with something like the kineticsnoise products (though it would seem to me that this would create leaf-space-leaf-space-leaf -- with the leaves being wood floor, subfloor, bsmt ceiling).

Seems like I'd probably screw up the neoprene/spring solution unless it's really the only way.

She's not fond of glued-down wood floors--says they feel hollow--but is willing to make the sacrifice if needed. (seems like nailing would help transmit the sound...or would it make a difference? No bass amps, no kick drums...)

We will eventually be selling this house, so I can't raise the floor 6" or anything like that--in fact, the less evident the difference from a "normal" floor is, the better.

Thanks so much in advance for your help--
Will

[Willangus]

bump...anyone? Do I need to give more information?

[Willangus]

quick update that might make this more interesting...I picked up the wood today and was told that floating this particular wood floor was not an option. (planks were too narrow)

So it looks like I'm either nailing or gluing. Shame, because from the additional research I was doing last night, looked like floating would be the way to go. I was checking out the Sonomatt LP from kineticsnoise's site, which basically looked like 3/8" of 703.

But this occurred to me just now--what about from top to bottom:

wood floor
"2nd subfloor" plywood to glue (nail?) wood floor to
Sonomatt LP or similar floating material
existing plywood subfloor
joists
ceiling

In other words, on top of the existing floor, put down a layer of the isolating material (Sonomatt), and since I can't float the wood floor directly on top of the Sonomatt, put down a layer of plywood on top of it (floating the plywood), and then fasten the wood floor to the plywood.

anybody see any issues with this? Seems like another way to float a floor when a regular method of floating isn't an option...?

I'd be especially curious to see if we could nail the wood floor to the 2nd subfloor...glue is expensive.

If that doesn't work, then maybe we're back to just adding as much mass as possible to the floor (via roofing felt or sheetblok or something).

Thanks,
Will

[Aaronw]

Hmmm...

Do you know if you have any type of insulation in the joists? What is the size of the joists? Is pulling up the Old Subfloor and option? What is the existing construction around the studio and upstairs (is it flanking in a particular area?) How is the drywall attached to the joists in the basement? Directly to the joists, or floating on RC?

[Willangus]

Hmmm...

Do you know if you have any type of insulation in the joists? What is the size of the joists? Is pulling up the Old Subfloor and option? What is the existing construction around the studio and upstairs (is it flanking in a particular area?) How is the drywall attached to the joists in the basement? Directly to the joists, or floating on RC?

Hey Aaron,

I haven't done a lick of work on it yet, so I'm afraid I don't know the answers to most of these questions. Pulling up the old subfloor is an option, though I'd imagine it would add at least another day onto our timeline. Just out of curiosity, what would I do after I pulled up the old subfloor?

I'll check if/where it's flanking tonight. The ceiling has recessed light fixtures and ducts, all of which yield some flanking. But as I said, it's not bad right now; I'm just afraid it's going to get worse with wood floor.

As far as insulation and ceiling attachment, I would suspect no insulation and mounted to joists..but again, I'm not sure.

[AVare]

If you goto NRC they have a study with dozens of floor/ceiling designs and actual test results.

[Willangus]

Awesome...I saw these before, but I guess I didn't read them carefully enough. Thanks for pointing that out, AVare.

So from these docs, I learned:
STC (airborne isolation)
- joists to ceiling is the main flanking path for airborne sound; therefore, adding insulation between subfloor & ceiling doesn't make any difference in STC if ceiling is attached directly to joists (as mine almost certainly is)
- in this case, the principal way to control sound is to add mass to the floor.

IIC (impact isolation)
- doubling the total mass of subfloor + ceiling adds 7 points to an IIC rating (iow, doubling the mass of the floor would add ~3.5 pts).
- biggest surprise for me: floating the floor on a resilient layer on joists and wood subfloors does NOTHING to impact IIC. (floating floors are apparently meant for use with concrete subfloors.)

Conclusions:
- the reason that everyone talks about what to do with the ceiling is not just because we usually have more control over it, but that working with the ceiling is a much better opportunity to control isolation because of the option of hanging it on RC.
- Adding mass to the floor/subfloor layer is the only way to make a difference, and even doubling the mass of the floor (i.e. adding another layer of ply, for instance) will only get me about 3 STC points.
- it doesn't seem to really matter if I glue or nail the wood floor down.

This last point -- gluing or nailing -- is the only sticking point (haha). It wasn't really discussed in the papers, except in terms of attaching the subfloor to the joists:

Attaching the subfloor to the joists using both construction adhesive and nails gave the same sound isolation as attaching it using only screws.

Anybody got any thoughts on this? I'd love to be able to nail down these floors rather than glue them -- glue is expensive, and the wife doesn't like the feeling of glued-down floors. If I'm just adding mass to the subfloor/floor and not worrying about floating anything, doesn't seem like nails vs glue would make a difference...? (haven't done this before -- do the nails go into just the subfloor or all the way into the joists? I thought it was just the subfloor...)

So maybe I was just being paranoid all along? I'm going to check it out tonight, but the answer may just be to plug up the recessed lighting and tell Amy to wear socks when she's walking around upstairs.

[Aaronw]

Can you add a layer of the underlayment similar to what is used w/ laminate flooring (Pergo, etc). Maybe putting this between the subfloor & hardwood will reduce foot traffic noise?

[AVare]

A couple of corrections on your conclusions.

So much is written about ceilings because they are usually the weakest link in sound isolation. RC is not an optimum method for increasing isolation, but is cheap and readily available.

Ceiling/floor isolation can also be increased by increasing distance between the leafs.

Andre

[Willangus]

Hey--

first to Aaron--I could add that extra layer, but from the descriptions I've read it looks like it's just 6mm-thick plastic sheeting. Don't know that it would do much to add to the mass...did you have something different in mind?

A couple of corrections on your conclusions.

So much is written about ceilings because they are usually the weakest link in sound isolation. RC is not an optimum method for increasing isolation, but is cheap and readily available.

Ceiling/floor isolation can also be increased by increasing distance between the leafs.

Andre, thanks for the corrections; both points taken. I don't really have ceiling room to spare downstairs, unfortunately, so I can't increase that distance. And we're not ripping up the ceiling (yet...?) so RC isn't really an option. But your thoughts are spot on.

Update: did some "experiments" last night. I had Amy stomp around in boots upstairs and also talk to herself (the cats got a good laugh out of that one) while I listened from below. Right now, the upstairs as I mentioned is almost all carpet, with a linoleum floor in the kitchen. (it will soon all be wood floor.)

Boots (IIC/impact):
I can hear the dull thud of her boots pretty well on the carpet, and on the linoleum it's as if she's walking directly above me on the ceiling--no damping at all. In both cases, this doesn't seem to be localized around the light fixture or the vent, but followed her around as she stepped...i.e., transmitted directly through the joists to the ceiling and into the room.

Speaking (STC):
Airborne noise is pretty well isolated. I could only hear her very faintly, even when she was speaking directly into a vent of what I know is a shared duct. No difference between linoleum and carpet.

So the main problem is impact. In fact, I'm beginning to think that the easiest solution might just be to set up a TV and a couch in the part of the house not over the studio so she can relax back there while we're tracking. And maybe to figure out a way to rig a "Recording" light off the digi 002. but that's for another forum...

-W

[knightfly]

First, I'd like to say that if Amy's feet are sensitive enough to tell whether a floor is glued or nailed, I hope you're taking advantage of that "sensitivity" to get really good "walk up your back" massages... Seriously, what has she walked on that this was obvious? About the only thing I can think of might be the self-stick stuff with a kind of spongy adhesive backing...

Second, if you include a resilient layer under ply as your "workaround" suggests, you don't want to "short it out" by running nails through into the lower subfloor.

Third, do you know yet what your floor joists are - spacing, span, size of joists? This may limit how much extra weight you should add.

Other than that, impact is a bitch. I was trying to help a guy on another forum a few months ago, had two spinster relatives above him who liked to cook 24/7, he could hear every chop of the knife on the cutting board, etc - to make matters worse, his incompetent contractor used ordinary HAT channel instead of RC for all his walls, ceilings... last thing I told him was to hire a lawyer...

You will need to add insulation between floor and ceiling, unless it's already there; if your space wasn't a garage, it's unlikely there's any there yet. If it WAS a garage, there MAY be insulation but I wouldn't count on it. THis can make about 10 dB diff in isolation, but NOT for impact noise - comments to date about that I'm in agreement with... Steve