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Room Within a Room and Weight
Old 2 weeks ago
  #1
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Room Within a Room and Weight

Hi all. I've just had a detached garage built in my back yard which has a 2nd story that I plan to use as rehearsal space for my band. Since we are a loud rock band and the closest neighbor is probably 100 feet away, I need to make the room as isolated as possible. I've been studying the Room within a Room solutions and think this is the direction I'd like to go, but my only concern is with the weight of such a build. The builder has told me that the second floor can support 30lb/sq ft. I'm looking at the possibility of laying mass loaded vinyl between a second layer of MDF for the floor, building a second set of decoupled walls with 2 layers of dry wall, and using a hat channel system to hang the ceiling, possibly with 2 layers of drywall there as well. How do I calculate weight and make sure I'm not overloading the structure?
Old 2 weeks ago
  #2
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Jason Foi's Avatar
 

MLV is a waste. Its just expensive mass. Standard building materials are the way to go. Isolating a second story is like your have is going to be extremely difficult. I dont know what your budget is, but you would be best off hiring an acoustician and consulting with a structural enginer.
Old 2 weeks ago
  #3
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Starlight's Avatar
 

+1 to Jason's reply.

Quote:
Originally Posted by futureicon View Post
How do I calculate weight and make sure I'm not overloading the structure?
That is what structural engineers do.

Quote:
Originally Posted by futureicon View Post
Since we are a loud rock band and the closest neighbor is probably 100 feet away, I need to make the room as isolated as possible.
That is what studio designers do.
Old 2 weeks ago
  #4
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Lots of useful info here. So the consensus thus far is that this is going to be difficult and that I should hire someone. I’m not actually looking to build a studio, just trying to deaden the noise enough so that the neighbors won’t be put out. The structural engineer who built the garage has already told me the load weight for the second floor, I’m just trying to figure out if there’s a way to translate that into overall weight. Obviously trying to save money here, otherwise I’d have simply hired someone to do it all for me.
Old 2 weeks ago
  #5
30lb/sqft can't be right. A person can stand in one sq ft, people would be falling through the floor. Double check that, if it's correct, you can't do anything.

The decoupled drywall sounds like your best bet for walls and ceiling. The floor would be an issue but you might consider doing the decoupled walls downstairs as well as long as you don't mind the sound being downstairs.

What about windows?

You can calculate the weight by knowing the weight of drywall and adding up what you will be using.

Isomax clips are great for the hat channel, I'd do that on the walls too.
Old 2 weeks ago
  #6
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Jason Foi's Avatar
 

Quote:
Originally Posted by futureicon View Post
Lots of useful info here. So the consensus thus far is that this is going to be difficult and that I should hire someone. I’m not actually looking to build a studio, just trying to deaden the noise enough so that the neighbors won’t be put out. The structural engineer who built the garage has already told me the load weight for the second floor, I’m just trying to figure out if there’s a way to translate that into overall weight. Obviously trying to save money here, otherwise I’d have simply hired someone to do it all for me.
A rock band is easily 110-120db. A fully decoupled MSM system with a couple sheets of sheetrock on either side gives you an STC of like 60. Sounds great, but STC is for speech, not music. So you end up with like a +/-30db reduction at LF depending on where you've tuned your MSM resonance. So, outside you went from 110db to 80db at LF. Possibly a bit more, but still loud. Then you have the floor. Unless you float your floor you're subject to the mass law, which is terrible for isolation. You could decouple a new leaf in the garage below's ceiling to maintain MSM systems, but even then, +/-30db reduction. When studios get a 60db reduction at LF they are using fully decoupled block or concrete walls and floors. The cost here is high 10's of thousands of dollars. To add more complication you also need to plan out ventillation which is just as much a pain in the butt.

The following pdf will tell you everything you need to know.
https://www.google.com/url?q=http://...HSi-ckMbWOPzC6
Old 2 weeks ago
  #7
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30 lb/sqft is typical for a residential construction. It is for the whole assembly. A10x10 room could support 3000 lbs, but it's important to remember that the number is based on a relatively evenly distributed load.

There is the other issue which was touched upon, which is a concentrated load. Each part would also have a max concentrated load number. Any individual sq ft can take more than 30 lbs, but much less than the full load. It's a more complicated calculation.

You could add up all the weights for people, equipment, drywall, etc to get the total weight. The problem is you still need to know where the forces are directed. Structural engineering is not something to DIY, as the failure mode is potentially catastrophic.

A proper room in a room is generally not feasible in a typical 2nd story residential build. Using the 1st floor would be better, as that is probably on a concrete slab.
Old 2 weeks ago
  #8
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Quote:
Originally Posted by jasonwagner View Post
30lb/sqft can't be right. A person can stand in one sq ft, people would be falling through the floor. Double check that, if it's correct, you can't do anything.
Hey Jason- I bought a couple pails of that other green glue type product from you a bit ago, how's your project coming?

In any case, that is a standard way to rate a ceiling/floor assembly. Floors have to be rated for a live load, but 30lb/sf means a 500sf floor can support 15,000lbs- not in one square foot, but given normal distribution of people and stuff and derating a bit for people jumping or shifting weights.

Last edited by RyanC; 2 weeks ago at 10:53 PM..
Old 2 weeks ago
  #9
Quote:
Originally Posted by RyanC View Post
Hey Jason- I bought a couple pails of that other green glue type product from you a bit ago, how's your project coming?

In any case, that is a standard way to rate a ceiling/floor assembly. Floors have to be rated for a live load, but 30lb/sf means a 500sf floor can support 15,000lbs- not in one square foot, but given normal distribution of people and stuff and derating a bit for people jumping or shifting weights. It also probably can't support 15000lbs in one sf either...
Quote:
Originally Posted by RyanC View Post
Quote:
Originally Posted by jasonwagner View Post
30lb/sqft can't be right. A person can stand in one sq ft, people would be falling through the floor. Double check that, if it's correct, you can't do anything.
Hey Jason- I bought a couple pails of that other green glue type product from you a bit ago, how's your project coming?

In any case, that is a standard way to rate a ceiling/floor assembly. Floors have to be rated for a live load, but 30lb/sf means a 500sf floor can support 15,000lbs- not in one square foot, but given normal distribution of people and stuff and derating a bit for people jumping or shifting weights. It also probably can't support 15000lbs in one sf either...
Thanks for clarifying that Ryan. The SR flooring I bought was rated at 1000lb/sq ft so that definitely confused me.

Build is going good, windows, doors, hardwood floor, electrical and HVAC all done. Just have to finish the soffit (purchased fabric stretching tracks) and do the studio wiring. Then I can get some acoustic tests done and put in the acoustic treatment. Still a couple months before any tracking starts.
Old 2 weeks ago
  #10
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Quote:
Originally Posted by futureicon View Post
Lots of useful info here. So the consensus thus far is that this is going to be difficult and that I should hire someone. I’m not actually looking to build a studio, just trying to deaden the noise enough so that the neighbors won’t be put out. The structural engineer who built the garage has already told me the load weight for the second floor, I’m just trying to figure out if there’s a way to translate that into overall weight. Obviously trying to save money here, otherwise I’d have simply hired someone to do it all for me.
This will give you an idea of the basic range of floor isolation systems.

https://kineticsnoise.com/arch/floating_floors.html

Obviously the best are the concrete only, tuned to infrasonic resonance...but 4" concrete is 25-30 lbs/psf and the isolators will put pressure points that have to handle that. That won't work here.

If you look over those, you will see that as you get to the thinner/cheaper products they will offer less isolation for impact noise. Unfortunately a drumset has a lot of impact noise, as do bass amps and cranked guitar cabs. A lot of this will depend on how loud you guys are.

All of these types of products are going to be specced out for an engineer- giving load limits per iso unit, possibly the newton force of the springs, and the other info you need to calculate how many you need, and how they will be distributed so they are loaded properly- also true with clips and channel. Then you are back to having pressure points that should probably be checked with an engineer- likely as long as you can put them over your joists you would be OK (for the wood deck products), but that could get a little complicated. But the thinner underlay products will offer a lot less isolation, especially when on a wood framed floor.

Quote:
Originally Posted by futureicon View Post
I’m just trying to figure out if there’s a way to translate that into overall weight. Obviously trying to save money here, otherwise I’d have simply hired someone to do it all for me.
What you need to do is get a clear picture of your isolation needs. What are your local noise ordinances? How well do you know your neighbors? You can get an SPL meter, stand at the property line and have the band play fully volume and get a pretty good idea of how much reduction you need from what you have now to where you need to be.

Better yet, if you get a umik usb and setup REW on a laptop, you will be able to not only use it as a SPL meter with A weighting, but also get an idea of how loud the LF is and if that might still be disruptive to the neighbors as well.

That all said floor systems like this are only part of the system, the room needs to be completely sealed (inner and outer leaves), and everything in the system from doors, service penetrations and ventilation and H/AC will need to match the floor system. Everything for this is heavy...drums are tough, not just because of SPL but because of how well they mechanically couple to a floor.

If you guys aren't that loud, you might not need *that* much isolation...still it's generally harder and more expensive then people are hoping. It's certainly true that a slab on grade is a much better place to start.

Last edited by RyanC; 2 weeks ago at 05:07 AM..
Old 2 weeks ago
  #11
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Quote:
Originally Posted by jasonwagner View Post
Thanks for clarifying that Ryan. The SR flooring I bought was rated at 1000lb/sq ft so that definitely confused me.
Wow that's a lot...I didn't see what it was, but with the plywood sheets it's some sort of damping system rather then a tuned-spring true floated type (which is always concrete or that sort of mass). Maybe they make it that high for some industrial applications- your designer probably called it out to provide some isolation from the rest of those industrial condos. But you're starting with a slab on grade there so a lot less of an issue in the first place as the slab is already well damped by the tamped soil below.

A true floated system is like shocks on a car- it can only support a relatively narrow range of weights by percentage of the weight of the deck. So if someone was going to add or subtract a couple thousand lbs, the slab would have to be really heavy (and then lots of springs) so that difference isn't too much to bottom out the springs.

That's sweet man, that's going to be a cool spot there.
Old 2 weeks ago
  #12
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avare's Avatar
 

Last time i gave the truth I was called a rockstar.

Stop and get pros to design or spend a lot of time here.

As the first floor is a garage, high isolation is not reauired to it. Build the second wall as a new external wall. High TL doors for garage. A fraction of the cost of a floating floor.

Hat channel can make things worse in the low end.

Note the suggestions that most of not all of the people would not even think of.

Master my tagline.
Old 1 week ago
  #13
Quote:
Originally Posted by RyanC View Post
Wow that's a lot...I didn't see what it was, but with the plywood sheets it's some sort of damping system rather then a tuned-spring true floated type (which is always concrete or that sort of mass). Maybe they make it that high for some industrial applications- your designer probably called it out to provide some isolation from the rest of those industrial condos. But you're starting with a slab on grade there so a lot less of an issue in the first place as the slab is already well damped by the tamped soil below.

A true floated system is like shocks on a car- it can only support a relatively narrow range of weights by percentage of the weight of the deck. So if someone was going to add or subtract a couple thousand lbs, the slab would have to be really heavy (and then lots of springs) so that difference isn't too much to bottom out the springs.

That's sweet man, that's going to be a cool spot there.
Ahh, that type of floating floor sounds like a ton of work. We just did the 1" SR board > 3/4 OSB > 1/4 hardibacker > 3/4 OSB > 3/4 hardwood. I was very concerned about running the scissor lift on the floor (pre-hardwood) but it was totally fine, the scissor lift was a little over 3,000 lbs.
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