Yet another M-A-M question(s)

I have read past posts on the M-A-M topic, and understand the M-A-M theory when building a Studio. My question for those with past experience is this, since I am getting close to the start of the build, I am getting asked question from some of the builders who I fully understand are "typical builders" and not "Studio Builders",,,,But this one question does have me curious.... I understand that the best build is the Mass Air Mass concept, but I was asked, "Is building a second, totally isolated room within the room, a justified expense for sound transmission reduction, when you, with regular 2X6 exterior walls that are double sheeted on both sides for mass, and your using Green Glue (which is to knock down sound transmission up to 70% if applied correctly) between the sheets,,,,is it still needed to make the room within the room as opposed to just beefed up construction on 2x6 framing??? I explained to them, the room within the room allows you to have the two Mass's totally decoupled so there is no flanking, and will give you about 3" more inches of air space between the walls. They asked, that with the Green Glue and double exterior sheeting and double drywall on the inside alone, wouldnt that be enough to keep the sound down enough that the neighbors stay happy (basically not hear anything)? I know the room within the room IS the best way to go, but in your opinion, using the double sheeting, double drywall and green glue, is it that much more a benefit going to the trouble and expense of building the room within the room??? Also, other question,,,I priced out insulation (but didnt buy it yet, but have to this week because the person giving me the big discount price is leaving the company) but I priced out R-19 for the walls that has the paper backing on it. Will that paper leaf create a huge problem, or is unfaced an absolute must? I also think my codes guy said I needed it with a barrier on it? :? Here (below) are the two designs I am asking about in the above MAM question. Both are Green Glued, double sheeted and double drywalled. One is standard construction, and the other obviously is the room in room design. Would there be a huge difference in sound absorption between the two?? (Sorry for these questions, but I am getting close to build time, and any question makes me nervous, so I have to ask (confirm) with you guys one last time. :wink: Thanks AJ

We're talking about an above ground installation here, right? The advantages of a seperate room within a room type construction are twofold. First, there is no direct coupling path between the inner wall and outter wall...ie.. vibration must be converted into sound, and then vibration again to get to the outside. and second, the air gap has a profound effect on the low frequency transmission loss. Will there be a huge difference between these two types of construction...not at high frequencies (voice range), but at low frequencies the seperate wall construction will be significantly better. Cheers Kris

I think it all depends on your noise reduction requirements. I would think more information regarding your situation would be needed. where are your neighbors, how loud will you be, etc. If you live in a neighborhood with houses ten feet from your studio, build the room. If you live on a farm, don't build it. If you're recording live drums the 'room within a room' is the only way to block the lower frequencies to the level you need, assuming you don't live on a farm somewhere. Similarly, I'll probably be beefing up my interior garage walls with a layer of Green Glued drywall. Then building a 'nothing fancy' single 2x4 stud frame with 2 layers of 5/8" sheetrock each side bolted to the concrete floor 'within' the room...(but far enough away as to not create a 'third leaf' effect.) Maybe using Green Glue again between the interior drywall sheets. This might be overkill, but I'm not willing to take the chance.

Not a lot of experience, but a hell of a lot in reading and reference on my end here - On your diagram for the separate wall frame - From what I've read of rod's book and on this forum, I would assume killing that layer of drywall on the outside of the inner wall would increase your isolation. and then taking that layer and placing on the interior would add more. the examples of 4 leaf systems on this forum would illustrate this. But most of them have the mass removed from the sides of the walls facing each other. Like, ----------------- DW frame/insulation air space frame insulation DW (additional layers etc..) ----------------- And conversly, adding one layer of DW next to that airspace would reduce the STC..

I just did some research on your old posts. You say this: "I have a neighbor only 20 ft away to the one side" "I play in 2 bands, and so we will be practicing here as well." Build the room, dude!!! MAYBE you could build a staggered stud wall which might be good enough...MAYBE a third inner drywall layer with GG...but whether you use 2x6's or 2x10's on a standard wall, the walls are still coupled and that's what hurts STC.... ***edited several times

cjbdrm wrote:

I just did some research on your old posts. You say this: "I have a neighbor only 20 ft away to the one side" "I play in 2 bands, and so we will be practicing here as well." Build the room, dude!!! MAYBE you could build a staggered stud wall which might be good enough...MAYBE a third inner drywall layer with GG...but whether you use 2x6's or 2x10's on a standard wall, the walls are still coupled and that's what hurts STC....

If I might jump in here......... the bottom line is this - especially if you have neighbors 20' away...... single wall construction will ALWAYS lose when it comes down to low frequency and flanking - that's just the nature of the beast. I don't care about mass (even single concrete walls won't get the job done - that's why in basements you still have to build inner walls - otherwise you could just mass up the ceiling and be done with it). and the green glue helps miles - but not enough on single stud walls....... Look at the green glue walls - single stud - and picture your bass player wailing away at 100 db - with a TL value of 23 @ 80 HZ - that puts sound levels outside your house at 77dB and your neighbors only 20'away.. and you still have drums to add in - (just LF for now) and it get's worse as the frequency levels drop...... now let's compare that to a double 2x4 wall - 24" centers - double 5/8" before any green glue application - this is taken from IR-761 - Test ID #TL-93-283........ AT that same 80Hz you now have a TL value of 36.6dB..... that's an increase in isolation of 13.6dB - so (just to get a perspective..... the 1st 6dB cut the volume in 1/2 - the next 6dB - in 1/2 again - and the last 3.6 cut's it by another roughly 30% Over a 200% improvement in isolation just by seperate walls - and ou haven't even added green glue into the equation yet...... I hope that helps........ Sincerely, Rod

To all you guys...THANK YOU!! And Rod especially for the statistics. I was sold on, from buggin you guys before, on the room in room build, but since the project sat idle over the winter, and now is to get restarted, some of the same old questions rise and I then again get nervous and feel the need for confirmation. :oops: Let me ask this question next,,,, Due to location of the build, I can not get any cranes near enough to assist with installing the beams, truss's etc. So, with MUCH help from Gulfo, and his talent in Sketchup, I will be keeping the last drawings he/we did, BUT I figured it would be much easier putting on the trusses if I had a 2nd floor to operate off of when doing so (over the tracking room). Also, this would obviously then allow me a large storage area over the tracking room as well (for current and future use). In building this, I plan to make 10ft high first floor ceilings in the tracking and control room, then on the 2nd floor, it will have 6ft outside walls with Scissor type trusses going up to the peak. (In the center will give me about an 11ft ceiling at peak, starting from 6ft walls on the outsides) (and with a span of about 21 ft across, I figure that will get me about a 5/12 pitch >?) Codes says for shingles I need at least a 4/12 pitch. Anyway, if/when I build this room within room, wouldnt that ceiling, then the new floor built above (uncoupled) now make the roof be a 3rd leaf?? Or would there be enough area on the 2nd floor that the roof wouldnt be a 3rd leaf consideration? Thanks and with this information, that should get me comfortable enough to light the green light,,, and maybe get started. And yes, progress pictures will be posted!! :wink: ITS GETTIN CLOSE!! :lol: :lol: You guys are awsome!! and Thanks again AJ Stick design with the 3 leafs I am asking about:

Oh yes,,,real quick..... is the R-19 insulation with the paperback barrier ok?? or is that going to create a big problem?? Codes requests it, but I know my codes guy will be ok with the unfaced if I ask him politely. :lol: He is diggin this project, and said he wants to see it happen and not bang me for every little thing, as long as its a safe build. :wink: Thanks AJ

studio911 wrote:

Oh yes,,,real quick..... is the R-19 insulation with the paperback barrier ok?? or is that going to create a big problem?? Codes requests it, but I know my codes guy will be ok with the unfaced if I ask him politely. :lol: He is diggin this project, and said he wants to see it happen and not bang me for every little thing, as long as its a safe build. :wink: Thanks AJ

The building official is correct - you do need the vapor barrier (although I prefer using poly rather than the paper faced) - BUT you need to (in your ocation) put it on the innermost walls - not on the outer walls...... Rod

Rod,

If I might jump in here......... the bottom line is this - especially if you have neighbors 20' away...... single wall construction will ALWAYS lose when it comes down to low frequency and flanking - that's just the nature of the beast. I don't care about mass (even single concrete walls won't get the job done - that's why in basements you still have to build inner walls - otherwise you could just mass up the ceiling and be done with it). and the green glue helps miles - but not enough on single stud walls....... Look at the green glue walls - single stud - and picture your bass player wailing away at 100 db - with a TL value of 23 @ 80 HZ - that puts sound levels outside your house at 77dB and your neighbors only 20'away.. and you still have drums to add in - (just LF for now) and it get's worse as the frequency levels drop...... now let's compare that to a double 2x4 wall - 24" centers - double 5/8" before any green glue application - this is taken from IR-761 - Test ID #TL-93-283........ AT that same 80Hz you now have a TL value of 36.6dB..... that's an increase in isolation of 13.6dB - so (just to get a perspective..... the 1st 6dB cut the volume in 1/2 - the next 6dB - in 1/2 again - and the last 3.6 cut's it by another roughly 30% Over a 200% improvement in isolation just by seperate walls - and ou haven't even added green glue into the equation yet...... I hope that helps........ Sincerely, Rod

Bravo, that's got to be one of the most well written, clearly defining explanation of the difference of sound isolation between single to double wall frame I've seen on this forum... IMHO. That statement deserves consideration for a Sticky. Marc

??? Nothing on the 3 leaf (3rd being the roof) question above yet ??? I know from reading on here that it is technically will be a 3rd leaf, but my question is, Will that 3rd leaf create problems after all the trouble I am going to go through for sound isolation?? Or should I be fairly safe with it being a roof and several feet away? Thanks again AJ

studio911 wrote:

??? Nothing on the 3 leaf (3rd being the roof) question above yet ??? I know from reading on here that it is technically will be a 3rd leaf, but my question is, Will that 3rd leaf create problems after all the trouble I am going to go through for sound isolation?? Or should I be fairly safe with it being a roof and several feet away? Thanks again AJ

It's hard for me to tell the exactly what you're doing from your diagram, but for starters the triple leaf effect only comes into play in an airtight situation (i.e. airtight between the leaves). I assume your storage area above isn't airtight, so no. Although it probably wouldn't matter because of the distance even if it was.

Thank You and yes it will NOT be air tight in the storage area. So it sounds like it should work out well then... and thanks as always!! :wink: AJ