Second floor studio questions

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WagTheDog

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I'm building a studio above my garage in the unfinished "bonus room". I will probably end up having to float a floor.....I'm going to use unfaced OC in the walls/ceiling....do I use the same thing under the floating floor or would it be better using faced? Or does it matter?

Thanks!
 
if its above the garage do you really need to float the floor... i mean , your cars probably dont mind the noise so much

:)

if it will be heated or cooled youll probably want to use faced insulation.. just for moisture barrier reasons.. or at least put some plastic sheeting up

i vote for decoupled interior walls and some correctly blown in wet cellulose (paper wont kill you - fiberglass sucks)
 
No, I've never heard the cars complain :) I'm not sure I'll have to float a floor...I'll probably save that decision for last....just trying to plan ahead though, just in case.
 
I am planning something similar, i.e. over a detached garage. After reading many threads on this forum, John Sayers' forum and elsewhere, and after buying Rod Gervais' excellent book, I have come to the same conclusion: given the risk, as Rod points out, that a floated floor may just be a big drumhead, it seems better just to add some mass to the floor and insulation underneath. I am assuming that it will still be worthwhile to build decoupled inner walls and (sloping) ceilings.
 
Jack,

Yeah, I just bought Rod's book a few days ago....haven't finished reading it yet but have read some chapters. So, you're saying that you think the floating of the floor would then create a third leaf? If you do go with extra mass on the floor, I assume you are still going to decouple the walls from the floor, ie. putting a 1/4" space between the bottom of the wall and the floor level with acoustical caulk for the gap?
 
I'm not sure I know what all the bad things are that a poorly designed or built floating wood floor can do (I don't think we are going to be floating concrete slabs above our garages...), but I think you're right, that it can become a third leaf. It can also have a resonant frequency that reinforces just what you are trying to damp out with room treatments.

Yes, I am thinking that the walls should sit on top of the massed-up floor, and they might ideally be decoupled from it with butyl pads or pucks under the bottom plate; but that, too, requires some science and math to do right, and I'm not sure how much it would really be worth. There's not much point in overdoing the wall design if the floor is going to be a weaker link. Besides, many double wall systems even share common top and bottom plates. Mine won't, so maybe nothing more than ordinary sill insulation is really warranted. I would decouple the tops of my vertical end walls and my sloping ceiling/walls from the outer structure, though -- that seems easier to do, with no tricky calculations required to do it effectively.

I would like to post some questions about this on John Sayers' site, but I need to do some drawings first. Meanwhile maybe we will draw some knowledgeable comments here.
 
Right now the flooring is 1" plywood sitting on 2X12 joists with a 2X16 center beam. I have 7" of cotton batts under the plywood and the ceiling of the garage is sheetrock.

If I don't float the floor, any ideas on increasing isolation? MDF on top of the plywood? What if I put Green Glue on the plywood and then a layer of MDF on top of that? There will be laminate flooring on the very top layer.
 
why do you want to soundproof anyway..
do you live in a city and need to keep the neighbors happy and the room quiet?

some ppl just go overboard... i live in the country and can easily control the noise level in my house
 
Well, you're lucky then...you can get as loud as you want....unfortunately, probably most of us live in cities with neighbors nearby, and laws about noise levels, etc.

Believe me, if I didn't have to soundproof, I wouldn't, and I'd spend my money elsewhere, like for more gear ;)
 
Alternating material types seems like a good idea, and Green Glue certainly has been given good marks for decoupling in walls -- certainly much better than standard construction adhesives, which apparently "couple" rather than "decouple." A couple of layers of roofing felt or a layer of sheet butyl also seem to have found acceptance. It would be good to know what's most effective (and then what's most cost effective).
 
Concerning decoupling....the basic idea as I understand it is to have your walls NOT touching the floor, spaced about 1/4" above floor level and caulked with acoustical caulk....

Your wall bottom plate is attached to the floor, right? The wall studs are attached to the bottom plate. Your walls are attached to your wall studs. Seems like that is "coupled", but there would be no way that I know of to do it any differently. So, it seems like it wouldn't make any difference if the wall sheetrock touches the bottom or not...also, how do people "finish out" their walls? Seems like using regular baseboards would couple the wall with the floor?

So much to learn :(
 
Leaving a gap at the lower edge of the sheetrock is just for getting a good seal: put in "backer rod" and caulk over that. It doesn't "decouple" the wall, which is indeed coupled to the floor if the bottom plate is hard down on it (and baseboard could only add to the coupling). You could put butyl (or some other suitable "rubbery" material) between the plate and the floor, but just as when you float a floor, that has to be loaded to the proper degree of compression to be effective. With a properly floated floor, the (inner) walls sit on top of the floor and their weight is supposed to be taken into account in calculating how many "pucks" to use and where to place them. It seems to me that it would be simpler, when not floating the floor, to make that calculation for floating the walls (i.e. no guessing about the weight of other parts of the structure, equipment, furniture, people etc.). However, I don't think walls necessarily need to be floated: if the studs are light sheet metal, or the gypsum board is hung on channel, for example, it may make little difference if the bottom plate is solidly connected.
 
How about putting down a thick caulk line on the floor, then put the wall sheetrock on the studs and let it down onto the caulk, then nailing or screwing the sheetrock to the studs? Or is that kind of what you were saying?

How much would it raise the STC if I put a thick layer of Green Glue on top of the existing plywood on the floor, then put a 3/4" layer of MDF on top of that, then a QuietPad (the ones normally used under laminate floors), then 6mm laminate?

Thanks for your advice
 
That way to caulk the bottom of the wall may work, but one slip it could get messy... and I slip a lot when I am hanging sheet rock. I'd put a couple of wooden spacers down and set the rock on them, get it fastened, then pull them out and caulk. Putting "backer rod" (long rods of closed cell foam) in the gap first will save you a lot of caulk.

I don't know what the best sandwich would be for massing up the floor. I am hoping that Rod Gervais will jump in and tell us both.
 
Sometimes I wonder with all this speculation if it would be better to just GO RECORD SHIT.
 
Unfortunately, if you lived where I do, SHIT is exactly what you'd record without all this crap :=( - I have one neighbor who's into big-block Mopar rigs (10-second ET's typically), another who's too damn dumb to train his dog not to bark constantly, farmers with tractors/hay balers, etc, two county deputies that're into automatic weapons just down the hill, I'm under the flight path for all the freakin' national guard chopper refueling excercises... can you say "bomb shelter"??!?. There is no time of the day or night when I can record anything acoustic without at least 3 takes; and naturally, the take I "nail" it is the one that gets "nailed"... Steve
 
Noise...

Hi Steve,
Have you tried Auralex Xpanders? They might help a bit (but not in lower frequencies). You can make some of your own easely.
Mike
 
Actually I've been doing that for years; but it's more for separation between mics, and only from mids up. The only thing that stops low end is mass-air-mass, and it isn't cheap. I'm in process of designing the new facility (may take a while) and the outer leaf will be sand filled, surface-bonded block; then a 3 foot gap to the inner leaf of 3 layers 5/8" gypsum on wood studs, with individually floated 4" concrete floors with each room's inner leaf built on floated slab. Highest resonance so far is 10 hZ, most are around 7 hZ. From calculations so far, I should be able to fire a 12 gauge shotgun into the ground outside and no one inside would hear it, or at most a dull rumble... Steve
 
Hey! Wow! that’s a major project! I am sure you will be ok then.

From my point of view, you may reduce the air space between the inner and outer shells but fill it with fiberglass wool.

I don’t understand “surface-bounded” ? Although I have tested that masonry blocs perform + 3 dB if painted. It seals the bloc.

Mike
 
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