Soundproofing when construction is not an option?

[DanCostello]

Hey all,

I work for a video game developer and the audio department recently got new offices after an expansion into a previously-vacant part of the building. Knowing that acoustic design is a rather niche skill and that acoustic concerns are best handled as early in the design/construction process as possible, we in the department all pressed for qualified designers to be involved from the beginning and identified a variety of potential isolation, treatment, and hvac issues to be addressed. Well, with corporate heirarchies being what they are, the details and degree of our concerns never percolated all the way through upper management and to the builders, and when those watered-down concerns were raised to the architect, his response was something to the effect of, "Oh yeah, I got this. Trust me." Judging by the results, he's got some experience at reducing sound transmission between adjacent offices in a normal corporate environment, but no experience whatsoever in actually building recording/post studios, so now I'm turning to you kind folks to see what sort of bandaids I can put on these rooms to make them more usable. There's a remote possibility that we'll be able to get corporate to redesign and rebuild the rooms from the studs, but I'm really skeptical that we'll be able to pull that off, and even if we do, it'll be several months away just due to ongoing project schedules, so I'm going to assume that the drywall that's up is the drywall that's going to stay there.

The big issues we're having are HVAC noise, reflections inside the room, and sound transmission between rooms. Our abilities to fix the HVAC are limited, but to the extent it's possible, HVAC is being dealt with by the builders. I'm going to hold off on the treatment issues until we get the isolation/transmission issues sorted out. It's the isolation/transmission issues I'm hoping you can help with.

What we've got are 5 identical offices and a separate sound booth.
The offices are 8'5" W x 12'4.5" D
The booth is trapezoidal. It's 5'10.5" W on one wall, 6'10" W on the opposite wall, and 7' Deep.

The roof is 14'7" from the floor and each room has a drop ceiling 8'11.5" from the floor. All walls extend from the floor all the way to the roof.

They're a little tough to measure, but my best guess is that the walls are all 5.5" thick. They're drywall on the surface with steel studs inside. I have no idea what they're filled with or how many layers of drywall were used.

In one corner of each room is a 36" door with a 2" frame. Each frame is about 3.75" from the adjacent wall.

The drop ceiling tiles are Armstrong 704A. Each of the 5 offices has space in the drop ceiling for approximately twenty four 2'x2' tiles. Within this grid are sixteen 2'x2' acoustic tiles, two 2'x'4 lighting fixtures, one 2'x2' HVAC supply vent, and one 2'x'2 HVAC cold air return (open directly to the area above the drop ceiling, not connected to ductwork). One of the acoustic tiles has a sprinkler head mounted in it.

The booth ceiling is similar, but smaller. It has space for about ten 2'x2' ceiling tiles. In that grid are one 2'x4' lighting fixture, one 2'x2' HVAC supply, one 2'x2' HVAC return, and about six acoustic tiles, including one with a sprinkler head.

Above the acoustic tiles is laid some kind of pink/yellow fiberglass-looking insulation. I don't know the make/model, but I did see the words "thermal" and "acoustic" on the paper backing. The area above the drop ceilings is mostly open, but there are some ducts, pipes, and wires up there.

I've attached a screenshot from a floorplan program showing how our rooms are laid out. I know that each room shows a slightly different square footage; that's merely an artifact of me being unable to get the walls in the right spot in the layout program. The real rooms are all identically sized.

Now that you know what the rooms look like, what are your suggestions for how I go about isolating them from each other as much as possible? The biggest culprit I see right now are the doors, which are standard hollow office doors and are not sealed in any way. Even once they finish installing the locks and latches (which they haven't yet), there will still be a visible air gap between the doors and their frames. We're looking at weatherstripping-style sealers to use on the door frames and sweeps to use on the bottoms of the doors, but I'm skeptical that will be enough.

But even if we fixed the doors, there is not much isolation through the walls. I really don't know what to do about this, except to clad the entire room (including the door) in 2 lb/sq ft mass-loaded vinyl. While I expect that will help some non-zero amount, I don't know how to figure out how much it'll help and whether that benefit will justify the expense and labor involved. Additionally, while cladding the room up to the drop ceiling would not be difficult, cladding the walls above the drop ceiling (assuming that's necessary) would be considerably more challenging.

Other than the mass-loaded vinyl, I really have no idea how to approach this. Everything I know (which is not much) about sound isolation points towards fixing the issue w/ construction, not working within an existing structure. So, that's where I'm at with this. Some of the other guys are chomping at the bit to put in a purchase order, but none of us have the experience to design it ourselves and I'm trying to make sure we do this right (or as right as possible). Got any ideas?

Thanks,
-Dan Costello.

ETA: I just re-read the forum rules and realized I didn't put down any goals for the ultimate level of performance I'd like out of this. Though it's vague, I suppose my answer is "as good as I can get." We've got 5 people supporting all facets of several different projects and the sort of material we handle ranges from quiet ambiences and vo recording to super loud weapon and creature sounds. As an example, yesterday, the guy across the hall was recording VO for a demo, and today they've been screaming their brains out for some kind of creature they're designing. I've been doing weapons and creatures more of the last couple weeks, while another guy is mixing ambient music tracks. With how things currently are, anybody working on speakers is audible to the rest of the department, and the whole department has to either shut down or move to headphones when somebody's cutting VO, and IMO, that's unacceptable. I'd like to be able to work on my stuff without disturbing or being disturbed by anyone else.

[JCBigler]

Hello Dan,

Welcome to the forum.

As you have surmised, there is not a lot that you can do to really isolate each of your offices unless you are able to engage in construction. That means tearing the walls out, building new ones with multiple layers of mass (drywall, plywood, OSB etc..) and acoustic insulation such as Owens Corning 703 or Rockwool in the air gaps between the walls.

Certainly sealing off the doors and windows, and adjusting the HVAC inflow/outflow and registers will help to knock down some of the ambient noise and cut down on noise getting into and out of each room. But I don't think you will get more than a few dBs of attenuation at best without being able to build a true two-leaf structure.

A couple of options that may help some is to purchase one or more of the off the shelf acoustic isolation rooms for the actual voice over/recording areas. Two of those are:

Whisper Room

and Vocal Booth

As for the actual offices, you can take some measurements and run some room mode calculations and build some acoustic treatments that you would hang on the walls. Treating the room with absorption, reflection, or diffusion will help you when you are mixing and editing your various music, effects, and voice.

If you go down the construction road, I would urge you to bring in a qualified acoustic designer who is familiar with and has a proven track record building recording studios and post production facilities. The difference that someone with those skills will bring to the table is night and day from what a regular architect or general contractor will be able to offer.

Since your facility is a full time professional production facility, you really do need to have a professionally designed and built recording and mixing facility.

[DanCostello]

Hello Dan,

Welcome to the forum.

As you have surmised, there is not a lot that you can do to really isolate each of your offices unless you are able to engage in construction. That means tearing the walls out, building new ones with multiple layers of mass (drywall, plywood, OSB etc..) and acoustic insulation such as Owens Corning 703 or Rockwool in the air gaps between the walls.

Certainly sealing off the doors and windows, and adjusting the HVAC inflow/outflow and registers will help to knock down some of the ambient noise and cut down on noise getting into and out of each room. But I don't think you will get more than a few dBs of attenuation at best without being able to build a true two-leaf structure.

Yeah, that's what I was figuring. In the mean-time, I found this post, which was kind of disheartening.

A couple of options that may help some is to purchase one or more of the off the shelf acoustic isolation rooms for the actual voice over/recording areas. Two of those are:

Whisper Room

and Vocal Booth

*sigh* Yeah, somebody floated that idea. I've never really been a big fan of those, since they sound kind of boxy, but they're definitely be better than what we have. Vocal Booth doesn't have prices on their site, but the Whisper Room model that'd maximize the interior space in our offices (MDL 84126 S) is just shy of $10,000. Five of those + one for the booth + shipping and we'd be getting close to $60,000. At that point, a consultant and new construction may be cheaper.

The Whisper Room also has an interior height of 6'8". I'm 6'5" in bare feet and the thought of brushing my hair on the ceiling every day makes me die a little inside. :-p The Vocal booth has an interior height of 6'10", which is better, but still not amazing.

If you go down the construction road, I would urge you to bring in a qualified acoustic designer who is familiar with and has a proven track record building recording studios and post production facilities. The difference that someone with those skills will bring to the table is night and day from what a regular architect or general contractor will be able to offer.

Since your facility is a full time professional production facility, you really do need to have a professionally designed and built recording and mixing facility.

Preaching to the choir....

-Dan.

[Soundman2020]

Hi there Dan, and let me add my Welcome as well!

As you already figured out, your architect was pretty much like most architects when it comes to acoustics: not very clued up! Sadly, architects don't seem to get much time learning about acoustics in their training.

OK so you are stuck with a bad situation, and few options for dealing with it. There is hope, but as with most things on this planet, it all depends on the mighty dollars sign. How much budget do you think you could come up with, realistically, to fix this? If the answer is in the hundreds of dollars, then there really isn't much you can do at all. On the other hand, if it is in the tens of thousands, then things look bright and cheery! The grey area in between those two extremes is not a good place to be...

Anyway, starting from the low end of that scale: If all you have is a grand or so per room, then I'd spend that on sealing, in all aspects. Work around the room carefully, and seal every possible nook and cranny, no matter how insignificant it looks, then seal your doors (which you have already identified as issues). But don't use ordinary weatherstripping for that: go a bit more upscale, and buy proper and suitable acoustic seals, from a place like Zero International: they have a pretty large range of good stuff to chose from. Check out their web site, and don't forget the threshold seal! That's a very important one: people tend to forget that a door has four edges, not just three. The sides and top are obvious, but that major crack under the door is a big deal. It MUST be sealed.

It's amazing how much sound can leak through a very, very tiny gap.

If the budget is a bit bigger, then I'd replace those useless hollow things with good solid-core doors, adding extra hinges.

After that, I'd go for the HVAC system. But that's likely a pretty big issue...

When you mention "HVAC noise", what exactly do you mean by that? Do you mean that you can hear the humming of the actual HVAC fans and compressors coming through the ducts? Or do you mean that you can hear the vibrations from that equipment in the building structure? Or do you mean that you can hear the noise made by the airflow itself? Or do you mean that you can hear sound from other rooms coming through the HVAC system?

to the extent it's possible, HVAC is being dealt with by the builders.

Oooo! That might not be a good idea! Remember how well your "expert" architect handled the acoustic design... do you really want to let equivalent "expert" builders try to fix acoustic problems with the HVAC system?

one 2'x'2 HVAC cold air return (open directly to the area above the drop ceiling, not connected to ductwork).

Hoo boy, do you have HVAC troubles, or what!!! And this was supposedly designed by an architect who claims to know all about acoustics? I have a hard time grasping that...

OK, so if the entire ceiling plenum is your return, then there's basically zero isolation anywhere. The way to fix that is to re-design the HVAC system. There need to supply ducts and also return ducts, as well as silencer units on both, to stop noise getting through. All of those need to be dimensioned such that the air flow rate is kept high enough for each room, while the air flow speed is kept low enough such that it does not produce any audible air noise. This is not something that the average builder can fix: it is going to need so expert re-designing and re-building.

The area above the drop ceilings is mostly open, but there are some ducts, pipes, and wires up there.

Just to clarify: so there is one single common plenum over all of the rooms? And the only thing between that common plenum and the rooms, is "acoustic" ceiling tiles?

But even if we fixed the doors, there is not much isolation through the walls.

I would suspect that the biggest issue is probably up through the ceilings, into that common plenum (assuming that that's what it is). Your walls might not be too bad, actually, compared to an open space up there, shared by all the rooms.

I really don't know what to do about this, except to clad the entire room (including the door) in 2 lb/sq ft mass-loaded vinyl.

You'd spend an awful lot of money doing that, and for very little effect. You already found one of my posts on this from a couple of years back, so you are aware of the issues. MLV is mass, so it does help to increase isolation. However, it is very expensive mass, and sound waves actually can't read price tags very well, so they don't care how much you pay for your mass.... You'd be a lot better off just adding a second layer of drywall on top of the existing layer (but make it 5/8" drywall, never 1/2"), and even better still of you put Green Glue in between those two layers. It would be less expensive, and far more effective.

What would be even more effective yet, would be to take off the existing drywall, put RSIC clips on the metal studs, put hat channel in the clips, and put the drywall back on again. That would gain you quite a decent amount of isolation, if done right. Assuming that the ceiling issue can be fixed.

While I expect that will help some non-zero amount, I don't know how to figure out how much it'll help

Mass Law. That's the set of equations in the world of physics that describe how sound behaves when confronted with a massive single-leaf barrier. Mass Law is not very comforting: At a rough guesstimate based on mass law, adding a layer of MLV to your walls would probably gain you maybe 3 to 6 dB of isolation, realistically. Not much return for a very large investment!

cladding the walls above the drop ceiling (assuming that's necessary) would be considerably more challenging.

I'd say that the ceiling itself is the bigger problem.

Everything I know (which is not much) about sound isolation points towards fixing the issue w/ construction, not working within an existing structure.

Very certainly that would be the best way to go, if you can come up with the budget. But there are some things (as above) that you can do, without needing to build anything new. The one thing that does make sense, is the RSIC clips plus hat channel plus new drywall. I don't know if you'd consider that "construction" or not, but it would make a very useful difference, and isn't that hard to do. The toughest part would be convincing the bean counters that you really do need to start pulling off the drywall that just got put on! But if you can get past that hurdle, then actually doing it isn't such a big deal, and you aren't really "constructing" anything new: you are just modifying something that is already there.

To my way of thinking, this would be your best get for the walls without going to major expense of building rooms within rooms. However, it does imply that you'd need to do the ceilings in a similar way, in addition to the door seals and solving the HVAV problems.

As an example, yesterday, ...

Wow! That's a pretty sad situation. Basically unusable for what you need.
What I mentioned above should go a long way to making the situation more tolerable. In theory, you could get an additional 10 to 20 dB of isolation above and beyond what you have now, and perhaps more. Subjectively, that would reduce the sound bleed to about a quarter of what it is now, or better.

There's other things you could do to improve it even more, if the budget could be nudged up higher.

So basically it is possible to fix the problems that you have, but the amount of "fix" depends exactly on the amount of money you are prepared to invest in it. More money = more fix.

I'd suggest first figuring out how much money you can put into this, then based on that info we can help you figure out what's the best way of using the money: how to get the LEAST "bang" for you buck here! (not the most bang for the buck! You guys want LESS "bangs" getting through, not more!)

- Stuart -

[DanCostello]

Hi there Dan, and let me add my Welcome as well!

Thank you!

OK so you are stuck with a bad situation, and few options for dealing with it. There is hope, but as with most things on this planet, it all depends on the mighty dollars sign. How much budget do you think you could come up with, realistically, to fix this?

I really don't know. Our local studio is a wholly-owned, though semi-autonomous subsidiary of one publisher, which is then owned by another, larger publisher, so there are multiple levels of budgeting and management involved where going past some fuzzy budgetary threshold for one level would involve kicking it up to the next level.

Part of it depends on how much we piss and moan, part of it depends on how much management things it's worth.

Part of it depends on how much we can make the best of our current situation, which is kind of a double-edged sword. If we do a great job in spite of poor conditions, then they can come back and say that we were bitching about nothing and just being fussy. If we do a lousy job, then we have our names on something that sounds like crap.

If the answer is in the hundreds of dollars, then there really isn't much you can do at all. On the other hand, if it is in the tens of thousands, then things look bright and cheery! The grey area in between those two extremes is not a good place to be...

The story of my life...

Anyway, starting from the low end of that scale: If all you have is a grand or so per room, then I'd spend that on sealing, in all aspects. Work around the room carefully, and seal every possible nook and cranny, no matter how insignificant it looks, then seal your doors (which you have already identified as issues). But don't use ordinary weatherstripping for that: go a bit more upscale, and buy proper and suitable acoustic seals, from a place like Zero International: they have a pretty large range of good stuff to chose from. Check out their web site, and don't forget the threshold seal! That's a very important one: people tend to forget that a door has four edges, not just three. The sides and top are obvious, but that major crack under the door is a big deal. It MUST be sealed.

It's amazing how much sound can leak through a very, very tiny gap.

Yeah, that's definitely near the top of our to-do list. We're waiting until the hvac stuff gets "resolved" so that we know what our baseline noise level is, so we can have a better idea of how much difference the sealing will have made. If nothing else, we're trying to be methodical.

If the budget is a bit bigger, then I'd replace those useless hollow things with good solid-core doors, adding extra hinges.

Interesting. I hadn't considered that, but it might be worth a look. And it's one of those things that might not seem so extravagant that management balks.

After that, I'd go for the HVAC system. But that's likely a pretty big issue...

When you mention "HVAC noise", what exactly do you mean by that? Do you mean that you can hear the humming of the actual HVAC fans and compressors coming through the ducts? Or do you mean that you can hear the vibrations from that equipment in the building structure? Or do you mean that you can hear the noise made by the airflow itself? Or do you mean that you can hear sound from other rooms coming through the HVAC system?

It's predominantly airflow noise. I'm pretty sure the airflow sound is from the air passing through the ductwork and not from the air passing through the vents - IOW, I don't think there would be any benefit to replacing these vents with vents that have larger openings.

I haven't noticed any kind of rattle from the ducts. And there's so much sound from adjacent rooms bleeding through the doors that I can't tell one way or another whether any of the adjacent room noise is bleeding in through the hvac. So far, however, I haven't been able to detect any bleed from the other rooms.

to the extent it's possible, HVAC is being dealt with by the builders.

Oooo! That might not be a good idea! Remember how well your "expert" architect handled the acoustic design... do you really want to let equivalent "expert" builders try to fix acoustic problems with the HVAC system?

Oh, I don't want to let anybody do anything. But the HVAC for the audio wing is part of a larger HVAC system that covers the entire building, and since the new construction (which was bigger than just the audio wing) there have been tuning issues with several parts of it, not just ours. For example, there's actually negative pressure in the building right now, which is causing some of the plenum return vents to work backwards and suck in hot air from outside (which means that the A/C has to be on full blast unless we want to bake). So any HVAC work is going to have to involve the guys who manage the whole system, and it's apparently going to take some time for them to sort out the issues, which are at least partly related to the construction workers having several doors open all day.

But for our rooms, they do have some plan to add "plenum boxes" (of what design, I do not know) which will allegedly cut down on some of the airflow noise.

one 2'x'2 HVAC cold air return (open directly to the area above the drop ceiling, not connected to ductwork).

Hoo boy, do you have HVAC troubles, or what!!! And this was supposedly designed by an architect who claims to know all about acoustics? I have a hard time grasping that...

It seems fine for a regular office, and I've even found diagrams on other web sites describing systems like ours as a good way of reducing sound transmission between offices. I'm sure it's fine if you're only worried about preventing your neighbors from hearing your phone calls, but blocking the sound of an alien tank battle is another matter.

The area above the drop ceilings is mostly open, but there are some ducts, pipes, and wires up there.

Just to clarify: so there is one single common plenum over all of the rooms? And the only thing between that common plenum and the rooms, is "acoustic" ceiling tiles?

But even if we fixed the doors, there is not much isolation through the walls.

I would suspect that the biggest issue is probably up through the ceilings, into that common plenum (assuming that that's what it is). Your walls might not be too bad, actually, compared to an open space up there, shared by all the rooms.

That's not quite right. There is not a common, open plenum across all rooms (that's actually how our last "audio rooms" were built). The walls do not stop at the drop ceilings, but rather they go all the way up to the roof. If I pop up above my drop ceiling, I can't see my neighbor's drop ceiling - there's a wall in the way. There are pipes and ducts passing through the walls above the drop ceiling and the holes through with they pass don't appear to be sealed in any way, but there at least is some kind of wall up there dividing the offices.

The toughest part would be convincing the bean counters that you really do need to start pulling off the drywall that just got put on! But if you can get past that hurdle, then actually doing it isn't such a big deal

Yeah, IF I can get past that hurdle.

That reminds me of the joke - do you know why Batman is the greatest superhero? His super power is money.

To my way of thinking, this would be your best get for the walls without going to major expense of building rooms within rooms. However, it does imply that you'd need to do the ceilings in a similar way, in addition to the door seals and solving the HVAV problems.

Yeah, the ceilings are what worry me. I'm not to hung up on the hvac noise - it was pretty quiet in the old rooms and I figure they'll eventually work out whatever is the problem with the hvac in these rooms. But as you say, redoing the walls isn't going to make much difference if there's a bunch of sound coming through the ceiling, and I'm really skeptical that we could get a full redesign of these ceilings.

I'd suggest first figuring out how much money you can put into this, then based on that info we can help you figure out what's the best way of using the money: how to get the LEAST "bang" for you buck here! (not the most bang for the buck! You guys want LESS "bangs" getting through, not more!)

*sigh* yeah, getting budget numbers is the tough part, at least for me at the bottom of the totem pole. It may be the case that we'll have to live with low-budget fixes for a while (like the door sealers) and see if we can get a bigger budget next year to do something more extensive.

Either way, thanks for all your help. I just settled on a house with a nice-sized basement, so I'll probably start planning out a basement studio in the next few months and will definitely be back for more advice. I expect that project will turn out better.

-Dan.

[DanCostello]

They're doing some work on the roof above me right now and... yeah... *sigh* I guess it's a good thing there's nothing above us. This would be funny if it weren't sad.

[JCBigler]

Since your architect insisted that he would design your new facility to have proper acoustics and isolated offices/recording areas, you could always sue him and force him to actually do the work that you already paid for.