French drainage system in Basement, how to handle?

[sharward]

...although he'd still need to beef up that upper leaf, so there would be some weight added to the structure.

[TomM]

Tom,

Do you have the option of using an interleaved cieling joist system? You might end up with the maximum ceiling height AND no connection to the floor joists. My studio is done this way as is Paul Woodlock's. You can end up with real room within a room and not have to worry about whether your current floor joist can carry the weight of drywall on the bottom because they won't be carrying ANY more weight than they do now.

len

Len,

That sounds interesting... by any chance, do you have any links to a good description on how I would do that? Did you have a thread going as you did it yourself?? Thanks!

[sharward]

Here's a thread showing beef-up of ceiling and interleaved (or often referred to as "staggered") joists:

http://www.johnlsayers.com/phpBB2/viewtopic.php?p=20222

When I did a search for "stagger joists beef" using the "all terms" option, this is the only thread that came up. Although it has been covered in other threads (meaning, there's more to see/learn if you do more searching), the above thread is the one that I recall having the greatest detail in terms of illustration and pictures.

--Keith

[TomM]

Thanks Keith!

After reading all that...i'm not sure i'd be able to get strong enough joists to support the weight of 2 5/8" on the floated ceiling with the interleaved joists..

Looking at this calculator... http://www.awc.org/calculators/span/cal ... cstyle.asp ...though i'm not real sure about what live load (psf) and dead load (psf) actually means.... and how to figure out the grade.. but it seems that it would be difficult to get joists that would be strong enough.

The room joists currently go from west to east (when looking at my picture)... so they run the long way. I would have to put joists in-between those...also running the long way.. about 19'.

[sharward]

I'm not the expert by any means on the whole "live load" vs. "dead load" thing... But you'll want to check out "Understanding Loads and Using Span Tables" on the American Wood Council site.

19' is indeed a pretty long span... ...You might be able to shorten that span with a beam or a wall that would allow the joists to have a resting point midway through the span. If that's the case, then you'll be able to support more weight on them, without having to increase the overall height of the joists, which would obviously be detrimental to your headroom situation.

Some food for thought anyway...

--Keith

[TomM]

Hey Steve (Knightfly),

Just wondering if you have that floor plan you drew up? If you could post it.... (if you forgot about it)!

Thanks!

[knightfly]

Actually I did forget; ever go looking for the eye of the hurricane, only to find a tornado?

The drawing I started isn't complete, I may have to start over to show my intent. Your irritating duct (#6) is gonna cause problems, so it would help to know if you've decided wether you can get rid of/re-route it or not.

I'll post what I've drawn so far, but it's nowhere near ready for prime time - just a concept so far, hope it doesn't just confuse things more... Steve

[TomM]

Yeah, I'm gonna have to leave the ducts there...

and of course, i have the electric panel also in my way..

I also got another opinion on the "french drain" that my home inspector said is filled in with some foam that should be removed so it can work properly....

The second opinion said it's NOT a french drain, it's insulation between the concrete slab and concrete walls.

SO.... I don't think I will be taking the insulation out.

The ducts are so close to the side wall, I think I will just box the whole thing to the side wall. My room won't have symmetry though...


It's not the best situation for a studio.... but I really need something that I can mix well in. I'm so tired of having crappy mix rooms where I can't get my mixes translating.

Beneath the ducts, from the concrete to the bottom of the duct is about 6 feet, 11 inches.

It runs perpendicular to the engineered joists... so the ducts can't be pushed up in them. (by the way, for some reason, i remembered the joists running the other way...when I wrote that one post).

SO what can I do??? How big of a problem are the ducts/electrical box?

[TomM]

How about something like this Steve??

Isolation is only a major concern in the "live" room/"control" room.

The red marks are where I could drill out holes in the stud there and place some quiet fans. One side reverse the fans to help with air flow.

The main room will only have 2 leaves. Outer concrete. Inner 2X4 studs, insulation inbetween, 2 layers drywall on inside.

EXCEPT where the vocal booth/closet is.... i'm not sure how to make that a 2 leaf only design without having insulation exposed on the inside of the closet. Will this hurt me?????

Where the number 2 is, I could leave that as concrete??

Then the walls around the closet would be staggered 2 leaf...

[TomM]

Also Steve, do you think I should bother with angling the walls in my situation?

[addr128]

Hey everyone! I'm in the process of a MASSIVE basement remodel of my home. Walls, floor, duct work, structural stuff, waterproofing (internal [SPAM LINK REMOVED BY MODERATOR] french drains ) etc...

Any suggestions for those that have done the basement thing, and specifically, those that have soundproofed a drum/band room. I know about mass and the green glue. For those that don't, one way is to hang two pieces of drywall, and you put green glue in between those sheets. The green glue converts sound waves into heat and dissipates the sound after about 60 days (from the glue hardening or whatever).

But there are those that say a room within a room is the way to go. Do I have to go that way? Will good sound barrier insulation with 2 thick sheets and green glue be enough to remove most of the sound?

It doesn't have to be completely silent. I don't want neighbors complaining anymore and I will have guitar amps blaring (metal and other aggressive music). But ideally I want to make it so I can play my drums late at night with family 2 floors above sleeping. Is that possible? Any cost effective suggestions anyone has?

Z channel or resilient channel necessary? I think I lose some head space with that and I don't really want to. Remember this is a basement, and half of the room is under ground.

thanks in advance for any suggestions!

[Soundman2020]

addr128, you really should start your own thread, instead of hijacking someone else's thread from ten years ago. You should also read the forum rules for posting (click here). You seem to be missing a couple of things!

For those that don't, one way is to hang two pieces of drywall, and you put green glue in between those sheets. The green glue converts sound waves into heat and dissipates the sound after about 60 days (from the glue hardening or whatever).

Green Glue does not harden. Ever. It is a visco-elastic polymer that stays soft indefinitely, as it is designed to act as a constrained layer damping compound. It doesn't really convert sound waves into heat either: it acts on sheer waves along the plane of the wall, which are indirectly caused by sound waves, and turns that into low-grade heat, but it doesn't really act directly on sound waves. Or rather, that's not what it's main purpose is. Sheer waves carry a lot of the low frequency energy through a wall, so damping those is very effective.

But there are those that say a room within a room is the way to go.

They are correct.

Do I have to go that way?

If you want good isolation, yes. But you'd first need to define how much isolation you need, in terms of decibels. You can measure that with a sound level meter. Once you know how many decibels of isolation you need, then you can choose the construction method and materials that will get you there. If you don't know that number, then you won't be able to design the isolation system that best fits your needs. It's the key.

Will good sound barrier insulation

Insulation does not create a sound barrier. Insulation is actually really lousy at stopping sound, when used on its own. However, when it is used as part of a correctly designed isolation system, it is excellent stuff, and can improve the isolation by an order of magnitude, or better. But not by itself. Insulation is mostly air, and air is a really bad sound isolator. Insulation is only useful as part of a properly designed system.

with 2 thick sheets and green glue be enough to remove most of the sound?

If all you have is a single leaf wall (even if it is built from a few layers of stuff), then you are limited by the principle of physics know as "mass law". It goes like this:

TL(dB)= 20log(M) + 20log(f) -47.2

Where "M" is the surface density of the wall, and "f" is the frequency you are interested in.

There's also a simplified empirical version of Mass Law that goes like this:

TL(dB)= 14.5log(M) + 23

Which is not frequency dependent, and just refers to the typical isolation that you get across the entire audible spectrum from a typical single-leaf wall.

As you can see, that basically implies that each time you double the mass of the wall, you get an increase of 6 dB in isolation for any given frequency. 6 dB is for the theoretically perfect mass in the first equation. Real-world mass (second equation) only gets you about 5 dB increase per mass doubling.

So let's say, for argument's sake, that you need 50 dB of isolation. A typical house wall (two sheets of drywall on a stud frame) will get you about 30 dB. So double that (add another 2 sheets) and you get 35 dB. Double that again (add another 4 sheets, for a total of 8 sheets) and you have 40 dB. Double the mas again by adding another 8 sheets (total of sixteen) and you get 45 dB: Double it one more time by adding another 16 sheets of drywall, for a grand total of 32 sheets, and you get the 50 dB of isolation you were looking for. 32 sheets of drywall will be nearly two feet thick... So if you do not want to build a "room in a room" structure, then this is your alternative. It will work, yes. No problems there, if that's the way you prefer to do it.

But ideally I want to make it so I can play my drums late at night with family 2 floors above sleeping.

Drums played normally measure about 110 dB. Drums played hard can be 115 dB. If you add in a backing track and a bass guitar, then you'll be getting close to 120 dB. Noise regulations in most residential areas around the world set the allowable maximum nighttime level at somewhere around 40 dB (maybe 35, maybe 45... it depends on the location). On the other hand, most people consider a level of 30 dB to be "silent", and that's about the level you get in a quiet bedroom late at night with the doors and windows closed and all electric stuff turned off, for a typical residential house in a quiet neighborhood.

Therefor, you'd need about 80 dB of isolation to get the "drums played very loud" level down to the legal level that will keep the cops away from your door, and 90 dB to get it down to the level of "bedroom silence".

All of those measurements are made at a distance of one meter (about 3 feet) from the drums, wall, or property line. In your case, you do have distance on your side, as sound does drop off slightly with distance, and you do have other barriers in between you and the "sleeping family", so with luck, all of that might knock off another 10 to 20 dB from your needs. With a LOT of luck, actually. But let's assume for argument's sake that you need to build a room that isolates to 60 dB. If you take a look at the "mass law" example above, you can figure out that adding more layers of drywall is going to work, but you'll need walls about 6 feet thick to do that, made up from many dozens of layers of drywall... That's probably not what you wanted to hear.

The only real option is fully-decoupled 2-leaf MSM "room-in-a-room" construction, with several layers of drywall on each of those leaves with Green Glue, and a large air gap that is filled with suitable insulation. It can be done, but that's pushing the limits of what can be accomplished in a typical home studio. Realistically, the flanking limit for a home studio built on top of a really good concrete slab, is about 70 dB, and even then that's hard to do.

On the other hand, the very best isolated studio on the planet is Galaxy, in Belgium, and they get just a fraction over 100 dB of isolation. It cost them several million dollars to do that. So it all depends on what your budget is. If you have a very large budget, with lots of zeros on the end, then you certainly can achieve high levels of isolation. However, if your budget is very tight, just a few thousand dollars for example, then you won't be able to get high levels of isolation. 40 to 50 dB would be the realistic limit for that type of budget. You didn't say what your budget is, but you did mention "cost effective", so I'm guessing that your budget does not have seven figures to it!

The issue is simply this: the decibel scale is logarithmic, similar to the way our hearing works. Increasing isolation from 30 dB to 40 dB basically means that you have to block ten times more energy. Going from 30 dB to 50 dB means you have to block one hundred times more energy. 30 to 60 is one thousand times more energy. 30 to 70 is ten thousand... 30 to 80 is 100,000, and 30 to 90 is one million times the energy you have to block. That's why it gets so expensive to get high levels of isolation, and why adding a few extra layers of drywall to a single-leaf wall is not useful.

Z channel or resilient channel necessary?

Not if you want high levels of isolation, and not if you build a fully-decoupled 2-leaf room-in-a-room. Resilient Channel is only useful for medium level isolation in situations where it is not possible to build a proper decoupled second leaf. It helps to partially decouple the drywall form the framing, but nowhere near as much as building a second frame.

I think I lose some head space with that and I don't really want to.

There are techniques for minimizing the loss of headroom in studios, but it is inevitable that you will lose some. At least a few inches, and maybe as much as a foot or so, if you need high levels of isolation.

and half of the room is under ground.

Right, but the other half isn't...



- Stuart -

[ellington12]

the above drawing is very well defined and helpful and i think it clarifies your question as well

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