Soundproofing existing rooms

[lotuscent]

Hi all - I have been gone from this forum for a few years... it's good to be back.

Here's my situation - I am teaching high school jazz combos and I have two adjoining rooms to my classroom which I want to soundproof for practice and to double as iso rooms for recording.

As I understand it, the best way is to frame a room within the room, with a floating floor and space between the old walls and new walls; layered mediums of different density, etc...

I know there are diagrams, recommended materials and such out there for this type of framing, and I have searched a bit, but not finding exactly what I need. I have to submit a plan and a budget to my administrators asap if i want to get this done by next school year - and I have finals, x'mas concerts etc. coming right up!
help!

any info or links you guys could give would be great. getting this done would help my program immensely.

thanks
peace

 

[pandamonk]

Hi all - I have been gone from this forum for a few years... it's good to be back.

Here's my situation - I am teaching high school jazz combos and I have two adjoining rooms to my classroom which I want to soundproof for practice and to double as iso rooms for recording.

As I understand it, the best way is to frame a room within the room, with a floating floor and space between the old walls and new walls; layered mediums of different density, etc...

I know there are diagrams, recommended materials and such out there for this type of framing, and I have searched a bit, but not finding exactly what I need. I have to submit a plan and a budget to my administrators asap if i want to get this done by next school year - and I have finals, x'mas concerts etc. coming right up!
help!

any info or links you guys could give would be great. getting this done would help my program immensely.

thanks
peace

For isolation, the best method is a MAM(mass air mass) construction. You need two leafs, and only two! You also need air-tight seals.

You should build double stud walls. Two separate rows of studs with drywall only on the outside.

The way you describe it, there is already a wall between the two rooms. In this case, your best chance of isolation is probably to add mass to either side(including ceilings). Also, make sure any doors are solid core and well sealed.

My suggestion is to find out what your weakest links are, and treat them. You can have a metre thick wall, isolated like nothing else, but if you have a single plane window in it, or a hollow core door, or door without adequate seals, then sound will simply pass through these weak links, and all the money spent making the thick walls will be lost. Also, you can an inner room completely decoupled from the outer, but create any small flanking path, and you'll ruin it.

 

[lotuscent]

ok, if i understand you correctly, i can use the existing walls as one of the masses in the mass/air/mass formula. so, frame inside the existing walls with dead air space in between, and sheetrock the inside.

i have also read that using another layer of different density in addition to the sheetrock can really help stop the sound transmission. true?

also, the entire building is on a common sub-floor/joist frame, so a floating floor would probably be necessary too? or not?

 

[pandamonk]

ok, if i understand you correctly, i can use the existing walls as one of the masses in the mass/air/mass formula. so, frame inside the existing walls with dead air space in between, and sheetrock the inside.

i have also read that using another layer of different density in addition to the sheetrock can really help stop the sound transmission. true?

also, the entire building is on a common sub-floor/joist frame, so a floating floor would probably be necessary too? or not?

It depends on the existing wall. If it is a standard stud wall, then no. It already is a 2 leaf system. If it is a single wall system, ie. a brick wall plastered on both sides, then this can work as one leaf, and you can add the other with a stud wall in one of the rooms. You can't add a stud wall on both sides, as this would make it a three leaf structure.

Difference densities/thicknesses can help, but you should really look for as dense/thick as possible within the budget(add as many layers of sheetrock to each side as the budget/frame allows).

Imo, a floating floor will be necessary. Could you provide a simple plan of the existing construction?

If the wall is a standard stud wall, then you could remove one of the sides, and build another stud wall on top for the floating floor, as shown.

 

[lotuscent]

OK, I have been distracted by concerts, finals, etc... but now I am back to figure this out.

Do I really need to remove the inside sheetrock before I frame another wall inside? This seems counterintuitive... it seems the extra layer would help. There must be some principal I am missing here.

Also, are there soundproof windows I can frame in in front of the existing windows?

What would be the best solution for the door - I need to be able to see in. so I was thinking about a door with a window in it, but perhaps a bad idea for the sound...

 

[pandamonk]

OK, I have been distracted by concerts, finals, etc... but now I am back to figure this out.

Do I really need to remove the inside sheetrock before I frame another wall inside? This seems counterintuitive... it seems the extra layer would help. There must be some principal I am missing here.

Also, are there soundproof windows I can frame in in front of the existing windows?

What would be the best solution for the door - I need to be able to see in. so I was thinking about a door with a window in it, but perhaps a bad idea for the sound...

Didn't i explain the principle? 2 is better than 3 in sound isolation. The distance of airspace between the layers is what improves isolation, as well as decoupling.

If you have 3 layers 1 foot apart, then you only really have the isolation of 2 layers 1 foot apart, in my understanding. Remove the middle layer and you have 2 layers 2 foot apart.

Here's a much better explanation.

Windows and doors tend to be the weakest links. The two leaf/decoupling/air-proof prinicples apply the same to windows as walls. Each leaf should be as massive(heavy/thick/dense) as possible. You can probably double the sheets on each side.

The same principle applies to doors as well. Preferably two solid-core doors, with as much space between as possible, sealed all round to make the rooms air-tight.

I doubt you will really need to improve the walls. Just sort the weak links. install a heavy solid core door, and a second window(making a 2 leaf system), and seal EVERYTHING you can, to make the room completely air-tight(then you gotta devise a way of getting air in, or you'll suffocate, without letting sound out).

 

[lotuscent]

thanks pandamonk. the explanation really helps. now i get it. this might actually be a lot easier than i thought.

peace

 

[gullfo]

if you carefully remove the existing drywall in strips, you can re-use those strips to beef up the inner portion of that existing wall/ceiling by layering them in between the studs and joists, then use wood cleats and plenty of caulk. then per pandamonk, build youself a set of new inner walls w/ drywall only on the inside (ie no drywall in the middle) and R13 insulation in each wall (air gap is good but it needs to be dampened). use a set of exterior grade double glazed windows to add a new window layer (if desired to keep the windows), and a set of exterior grade solid core doors.

this should give you a good amount of isolation and leave you with just flanking transmission which hopefully is minimal in comparison.

good isolation is not easy though... you need to seal everything, you need to seal up any new holes you create like outlets, switches, hvac, lights, etc. add the ventilation, and then once you're all done with that, you have to treat the room because now you've trapped it all into the room(s)...