Another Moon Studios

[mtomlins]

Hello,

I have recently started a thread over here at GearSlutz (http://www.gearslutz.com/board/photo-di ... udios.html) about our new house with two existing large-room studios. One of the first questions I have is starting with the floor - it already is squeaky, so I'm assuming I will need to pull it up, glue it and screw it back down. The room below has a drop-ceiling installed, but no other insulation other than that. Thus, the question is how to isolate and insulate layer-by-layer from the drop ceiling below...all the way up to a nice bamboo finished floor on top. I am not currently a professional recording engineer or studio, but that's not to say the future for this space couldn't become a more serious commitment. But, I'd rather get the floor set right before doing anything else because it's the most difficult to change later.

The starting room looks like this:


Cheers and thank you in advance,

-mt

[edited: we decided to name our two studios "Another Moon"]

[Soundman2020]

Hi there "MT", and welcome!

The most important question you need to answer before you can plan this, is simply: "How much isolation do you need?" In other words, how many decibels do you need to stop getting through from the room above to the room below. Once you have an answer to that question, it is fairly easy to figure out how you need to build the floor, walls, ceiling, doors and everything else, in order to get to that amount of isolation.

If you don't have a number, then nobody can tell you what you need to do: It's sort of like asking your friends how to get to "the vacation spot", but nobody knows where that spot is! Nobody can tell you how to get there, until you tell them what you want it to be....





- Stuart -

[mtomlins]

Thanks Stuart, I get it! I can imagine once I get into the space I could start taking some measurements, like:

- when my wife is rockin' out in the studio below, how much sound (in db) are coming up through the floor?
- when the neighbors are mowing their lawn(s), how much sound comes in through walls/windows?
- when there's a plane flying overhead, how much sound is coming through the ceiling/skylight?

I suppose I should consider getting a simple sound meter for all this measuring, eh?

Generally, I read on the forums about the MAM (mass-air-mass) concepts for isolation...I suppose more layers means better MAMAMAM, and thus more reduction?

Still reading on this one...

-mt

[Soundman2020]

I suppose I should consider getting a simple sound meter for all this measuring, eh?

Right. Decent ones go for about US$ 100 on e-bay or Amazon. But avoid the cheap Chinese junk that goes for around 25 to 50: those really are garbage. Get an Extech, Galaxy, or something like that, in the $100 range. Make sure it has both "A" and "C" weighting, and also "Fast" and "Slow" response. It might have more features, but those are the bare minimum.

Generally, I read on the forums about the MAM (mass-air-mass) concepts for isolation...I suppose more layers means better MAMAMAM, and thus more reduction?

Actually, no: it means LESS isolation, believe it or not!

Adding extra leaves reduces low frequency isolation. Adding extra mass to either of the two leaves in MAM will increase isolation, and making the air gap bigger will also increase isolation. But adding more layers in the manner you mentioned will reduce isolation. Single leaf is terrible, 2-leaf is fantastic, 3-leaf is poor, 4-leaf is bad, 5-leaf is darn lousy....

Not intuitive, but very real.


- Stuart -

[mtomlins]

Adding extra mass to either of the two leaves in MAM will increase isolation, and making the air gap bigger will also increase isolation.

That is not intuitive, but perhaps it has something to do with the dissipation low frequencies through different density of matter?

The floor joists consist of 2x12" on 12" center, to allow for crossing a huge 21' span without load-bearing posts in the middle of the studio below. Then considering the extra 6" for the drop ceiling - I might have up to 18" of air space between the leaves.

Which would leave the next question - how to increase the mass/density of the floor above AND the drop ceiling?

Thanks again for the advice!

-mt

[mtomlins]

how to increase the mass/density of the floor above AND the drop ceiling?

Sorry for quoting myself, but I am learning about double leaf construction and it's starting to make some sense. To improve the upper leaf (the underside of the subfloor above the drop ceiling below)...I could add 5/8" drywall with green glue directly to the bottom of the subfloor above. I think the idea is to increase the mass of the upper leaf.

But here's the question, considering that the subfloor (above) is very squeaky right now - I'm planning to pull it up completely and then screw it back down. It makes sense that I'm basically starting over from scratch with the floor above then. In the end, I plan to finish with an engineered hardwood or bamboo flooring.

I'll keep reading threads...

-mt

[stevev]

To improve the upper leaf (the underside of the subfloor above the drop ceiling below)...I could add 5/8" drywall with green glue directly to the bottom of the subfloor above. I think the idea is to increase the mass of the upper leaf.

That's the right idea. Increasing mass will increase your isolation (if done properly). As Stuart said, you do need to get some idea of what kind of isolation you need/want to start with though. Given that you're pulling up your floor it might be easier to put one, or even two layers of 19mm chipboard flooring down (if possible) and float your bamboo floor over that, rather than trying to beef up the floor from below.

It would also allow you to pack and level that floor surface as any of the 'click-lock' systems of floor have a pretty low tolerance for level variation in the surface you're laying them on.

Also keep in mind that by doing this kind of retrofit, you're adding considerable weight to a structure that wasn't intended to have considerable weight added to it. It's at this point that you need to figure out how much weight you'll be adding (by figuring out how much isolation you need) and then you might need a structural engineer to confirm the kind of extra load you're looking at.

To give you a real world example from my rooms, albeit vertically opposed rather than horizontal. Between them I've got two layers of 16mm Fyrchek plaster on one wall-200mm air gap filled with 24kg per cubic mtr fibreglass insulation-2 layers of 16mm Fyrcheck plaster on the other wall. The rooms are not connected in any way except for the concrete slab and the isolation is excellent. You can hear a little bit of kick and snare from a drum kit but that's about it. I should measure properly but I think i'd be around 55-60DB isolation.

Which would leave the next question - how to increase the mass/density of the floor above AND the drop ceiling?

If I understandcorrectly, your drop ceiling would be pysically attached to the floor joists of your upper room?

This is where you have to be REALLY careful about loading up that structure. one layer of 16mm plaster for your drop ceiling comes in at 13kg per sq mtr. 2 layers is 26kg's. If you've got a couple of extra layers of flooring on top you could be pushing 50kg per sq mtr which is a very significant addition in weight and shouldn't be added without some kind of on-site professional advice.

So, I guess it comes back to......how many db's of isolation do you need?

[mtomlins]

Excellent - thanks...I'll see about calculating total estimated load in the studio above. I'll see about contacting a local architect or engineer to help me see about that. I did confirm with my wife about her plans for the studio below. She might be willing to let me drop a few posts into her space as support. Combined with a cross beam in the middle of the span, that might do the trick.

Since this is a project studio and not a professional studio, I have a lot less gear overall. No heavy consoles, outboard gear, etc. Heck, I don't even have a lot of guitar amps and stuff that might weigh a ton. I also don't estimate having live tracking sessions in that room with a large number of people.

Better safe than sorry.

-mt

[mtomlins]

Been a little while since an update, and only a little work in the studio. Mostly we've been working on other parts of the house and getting unpacked, settled and returning to our normal selves after that whole endeavor.

One important part of the progress in my studio work is on the topic of the bouncy floor - which is nearly 40 years old and needs repair. I have confirmed with several contractors and architects that the structure of the 20-foot span with 2x12" joists at ~12" on center does support the max loads estimated for the studio above. But still there is some annoying bounce in the center of the room. The current direction we're headed is to add "suspension studs" into the design whereby the second floor below is tied into the rafters and ceiling joists above by 4 posts. We would then be adding a beam underneath the floor connecting the 4 posts so as to "cradle" the middle of the floor span. The structural architect estimated that the 1/2" bounce in the floor would be greatly stabilized, but also the maximum load for the floor could be increased by nearly 8x. It seems a conservative estimate given the division of the total span of the floor by 3x and the connectivity to both the roof rafters and ceiling joists above by about 3x. Excuse the rough back-of-the-napkin calculations.

Below you'll see the incorporation of the 4 "suspension stud" posts into the layout for the room:


And a 3D rendering of the room layout ideas:


Sweet Home 3D also gives you "fly through" movies from your rendering, if you're interested:


Of course, I found a used conference table for a console desk on craigslist:


As always, your feedback is welcomed on any subject or idea here - especially since I haven't started building anything yet.

Thanks in advance,

-mt

[Soundman2020]

That sounds like it would be a good solution, structurally, especially if your structural engineer has put his stamp of approval on it.

However, it will be very detrimental to your isolation. It will tie the inner leaf very firmly to the outer leaf, so all vibrations picked up by your studio floor and walls will be transmitted directly to the roof, where it will be radiated into the neighborhood. Likewise, and sound vibrations that happen to strike the roof from outside, will be transmitted through this structure into your floor, which already acts like a drum head, and will therefore transmit those sounds into the room, as if it were one huge loudspeaker cone. So any sound outside, such as thunder, rain, wind, overflying aircraft, traffic, dogs barking, lawnmowers, radios, telephones, people talking, etc. could potentially by sent inside your studio, and be radiated by your floor.

So I'd suggest you take a serous look at getting that structure hung from isolation hangers, that will support the load just as well but also provide acoustic decoupling to prevent sound from being transmitted though. You will also need to either place those support columns between your inner-leaf and outer-leaf walls for the various studio rooms, or build decoupled soffits around them as part of the inner leaf, to separate them from the outer leaf. You'll probably want to get someone like Mason Industries involved in doing that, as they have the expertise and the products to do it right. They will do all the calculations for you, and recommend which of their products will do the job, and also how they should be installed. This isn't a job for a normal architect or contractor: let the experts handle it.

- Stuart -

[mtomlins]

As always Stuart, you bring excellent advice to your observations. My takeaways from your comments are:

1) as the purpose of the suspension posts is simply to minimize the "bounce" in the floor, we should be careful to not tie them directly into the outerleaf of the whole building - specifically in this case, the roof rafters. If things are tied together then sound vibration will travel right along to the roof and become a giant speaker into the surrounding municipalities. At this point, I am just considering that the larger open room of the studio will be generally sound isolated, but the 2 iso booths be built as rooms-within-rooms (decoupled, separated, sealed).

2) as you state, if it will be necessary to still tie into the roof rafter, consider isolation hangers instead of just bolting directly into the joists/rafters. Since the location of the posts isn't required at specific points for structural load, we have some flexibility in where they are located. We also might just connect to the ceiling joists and not directly up to the roof itself. One of the architects actually suggested running beams above the ceiling joists to tie all the posts together. We could even build a truss in the attic space that distributes support laterally, while not touching the roof at all.

3) since the location of the posts is flexible, I can work them in between the spaces between the walls of the different rooms (in the 'S' of the MSM). I think my next work will be to start adding the double-walls around the layout and work the post locations into that layout.

Thanks Stuart - much appreciated!

-mt

[xSpace]

"The current direction we're headed is to add "suspension studs" into the design whereby the second floor below is tied into the rafters and ceiling joists above by 4 posts. We would then be adding a beam underneath the floor connecting the 4 posts so as to "cradle" the middle of the floor span."

If you are fixing a bouncy floor why is a beam underneath that floor, standard procedure, not enough to fix the problem? What does the roof have to do with any of this?

[mtomlins]

Brien - good question...why not just add a massive multi-lam beam across the center of the floor span below?

Simply to avoid having to install posts in the middle of my wife's studio space below. Obviously any additional support for the floor would tie into the surrounding structure - 1st floor, walls or ceiling/roof. We are also considering an alternative design that avoids the ceiling all together and just ties in diagonal truss beams inside the walls as Stuart suggested. Those diagonal beams connecting the walls to the posts to the floors would be decoupled appropriately. (I'm open to suggestions). They might also extend down into the first floor studio, but only at the upper sides of the studio below - and not giant posts in the middle of the span.

Thx for keeping the ideas going...

-mt

[xSpace]

"The floor joists consist of 2x12" on 12" center, to allow for crossing a huge 21' span without load-bearing posts in the middle of the studio below."

Ok, I have one dimension, 21 foot span. There has to be another and I am wondering what that is

A glueLam can span the distance(the unknown distance) and reduce the flex and not require posts. In any event, with a wooden floor upstairs I assume a wooden floor assembly downstairs. This means that IF you had to install load bearing posts on the first floor you would also have to install transfer bearing posts underneath those posts to the Earth.

I will add that the one time that "diagonal truss beams" was mentioned was when you did that.

[mtomlins]

"There has to be another and I am wondering what that is"

<- oh yes, it's nearly square.

The joists run 21' across the span, with the other dimension being 25' - with an additional "nook" space as you can see in the layout. Running a large beam under the middle of the floor is complicated. The space below is larger in width than the 25' due to some other changes and additions to that space, including a protruding 10' addition out one end and the home stairway access on the other end (e.g. the door into my studio above is in the middle of a stairway).

For the first floor "sun room" protrusion, they already installed a very large beam running about 19' parallel to the 21' joist spans in the ceiling above. The load maximum for that beam would be perpendicular to the 25' beam we would put in the ceiling. That end is compromised already due to there being no contiguous wall connection to carry the load down to the ground. At the other end, there is also no wall underneath to connect the load back to the ground - it's under a stairwell landing that is already constructed with sistered 2x12 joists. The original owners who built the studio addition were a painter (upstairs studio) and a sculptor (downstairs studio). Paintings aren't heavy, so the floor didn't need to be that massive. Sculpture is heavy - VERY heavy, so he used the downstairs studio with concrete floor. Thus, I have the dilemma of wanting to support more load and eliminate bounce in the floor to support a music studio that weighs slightly more than a little old lady and her awesome paintings.

As I stated before, the various contractors and architects that have given me tips or advice did clearly state the best options to connect load back down to the ground is limited to 2 parallel walls at either end of the joists on the 21' span. You can carry center load out to those walls with a diagonally connected beam (e.g. equilateral triangle) or up through the ceiling joists and/or roof rafters above the second floor. The triangle truss at the sides of the room seem the most practical to me and probably the strongest way to tie back to the best load bearing walls. My wife even agreed to have some cantilever support from her space below - imagine a diagonally connected beam from the room below, maybe 36" at the upper ceiling corners on either side of her space.

No matter what we do to help support the floor and load, I really appreciate Stuart's advice: be careful to isolate them with a soffit or box to preserve the inner leaf.

-mt

EDITED: "just ties in diagonal truss beams inside the walls as Stuart suggested" - you are right to clarify me there, it wasn't his suggestion for the diagonal beams - just that any post or beam inside the space should be treated as outer leaf, and separated from the inner leaf appropriately.