The other question still remains: do you think those acoustic putty pads _could_ make up for the isolation loss at the electrical boxes?
Time for a "blunt and to the point reality check:" If you have your outer leaf INSIDE the room (pillars exposed), and your inner leaf walls connected to both ceiling and floor of the outer leaf, then there really isn't any point at all to be worried about electrical penetrations! That would be sort of like worrying about a drippy tap in your kitchen sink, while there's a huge flood raging through your living room. In more colloquial terms, putting putty pads around your multiple electrical penetrations while you also have multiple very solid flanking paths all over, and the outer leaf inside the inner leaf, would be akin to rearranging the deck chairs on the Titanic as it sinks... It might make you feel a bit better, but serves no useful purpose at all. The problem is not the drip from the tap (electrical penetration): the problem is the raging flood (multiple large flanking paths).
Your studio appears to be in some type of old office building, or industrial building, or commercial building. Is that correct? If so, that implies that there are other people doing other things in the area above you, or the area below you, or both, and/or also the areas on either side of you. With your inner-leaf walls fully coupled to the ceiling above you, and to the floor below you, and the structural pillars, you basically have no isolation at all from structure-borne noise. Period. end of story. Any noise that is present in the building structure itself, will get into your room. Things like pumps, motors, elevators, water running in pipes, doors opening and closing, people walking on the floors, things dropped, perhaps even deep rumbling from traffic if the building has a parking lot where the apron or slab is directly connected to the building itself. All of that noise will get into your room, totally bypassing your isolation system. You have zero isolation from all of that. Probably also including other powerful external sounds, such as thunder, low-flying aircraft, helicopters, large trucks on nearby roads, etc. Anything that could trigger a natural resonance in the building structure itself, will get into your room, with no isolation.
Is that what you want?
Probably not, but that's what you are going to get.
i decided to keep the columns exposed, for aesthetic purposes, as opposed to acoustic purposes.
I like the look of them, and the detail - especially along the ceiling.
You are absolutely bypassing any isolation you might have had otherwise from the double-leaf walls, and the HVAC silencers, and all the rest of it. There really isn't much point in doing any of that, if you have the outer leaf inside the inner leaf, and fully coupled to it. ou could save a lot of money by not trying to isolate at all, because the isolation is going to be very low anyway with coupled leaves and major flanking paths.
Even worse, since the inner-leaf walls themselves do also have their own natural resonant frequencies (separate from the MSM resonance of the system), it is possible that they could actually
amplify some frequencies present in those building structure noises, which would cause them to be heard LOUDER inside your rooms, than they would be heard elsewhere.
The math for coupled systems would take a bit of time for me to work through, and I don't have much time right now, but at a rough guess I would estimate that your studio will not isolate much better than about 25 dB, if that. That would likely be something like STC-30 at best, and maybe IIC 25 (IIC measures impact isolation). I can't see that being usable as a recording studio.
For a better understanding of what impact noise is, and how it affects building floors, take a look at IRC-IR-802, put out by the National Research Council of Canada. You might be able to find that by googling it. If not, PM me...
Of course that will weaken the isolation, but it looks nicer than having them covered up with drywall, so i decided to go that route. But it was an aesthetic decision (and a little bit a cost issue as well - isolated ceiling)
You seem to be way underestimating the seriousness of the issue here. It's not going to "weaken the isolation": it is going to trash it entirely.
Yes, it would be nice to have architectural features like those pillars visible in the room, but you need to make a very basic decision here: Is this space going to be a recording studio, or is it going to be an architectural statement? Is the basic reason why the place exists to emphasize the structural features of the building, or is the reason to create a place where you can rehearse, track, mix, and master great music?
Right now, it seems you have decided that it is the former: just a nice looking office space that looks like a studio, but without actually being intended or functional as a studio. In other words: It seems that your most important priority is that it has to look good, but it really doesn't matter if it isolates well, or if it sounds good. That would seem to be what you are saying. If so, then that's fine! That's your decision. It's your money, and you can spend it whatever way you want. As long as you are aware that you have the wrong priorities for a studio, and as long as you realize that you have false expectations if you hoped it would be a great place for recording. If your number one priority is that it must feature the architecture of the original building, with no regard for isolation or studio acoustics, then so be it! No problem! Your call. As long as you are OK with it not being isolated, not sounding good, and not working as a recording space. That's fine. I have been in a few "studios" like that, and they look wonderful... there's two that I can think of right now which were even featured in architectural magazines, and decoration magazines, because they really did look very, very good: no argument about that!.... but they didn't seem to get a lot of booking time as studios, and they both ended closing down after couple of years of emptiness, going out of business.
If that's what you want, then that's not a problem! If architecture trumps acoustics for you, then fine!
On the other hand, if you want your studio to actually work as a
studio, then THAT should be your first priority: Make sure it is isolated well (to studio levels), and also sounds great (with studio level acoustics), so that the clients keep coming back for more.
Don't get me wrong: it still has to LOOK good, of course, if you want to keep your clients coming back. Looks are important: nobody wants to record in a dingy, ugly, studio. But the looks should never,
ever take back seat to the functionality of the studio as a studio: If you want to build a recording studio so you can make money recording, then firstly it should be designed and built so that it can make money as a recording studio! That sounds sort of obvious, but often isn't. Then SECONDLY the decor can be done to make it look great too. If you want to keep the style, then build fake pillars inside the rooms, that look exactly like the original pillars, but that have no structural function! Make them out of wood, or plaster, or drywall over framing, or even concrete blocks (if the floor can support the weight). Make them look identical, if that's what you want, but WITHOUT being part of the building. And place there where the acoustic response of the rooms dictates, not where the building structure dictates. You could even build them as acoustic devices: make them hollow and build acoustic treatment devices inside them, with hidden exposure to the room air. Or make them into storage closets, or a mic closet, or hide a fridge inside full of beer, or whatever.
Etc.
There are many ways of getting the "look" that you want for the studio, but you should never choose a method that seriously compromises the isolation and functionality of the studio.
You aren't the first person to run into this issue, and you certainly won't be the last. I've had a few clients who have been down the same path you are going down, but then changed course.
If you want an example of such a studio, take a look at the Studio Three Productions (
thread about Studio Three Productions' studio). When they hired me to do the design, they had already built a large part of the facility, including many internal walls, and it was too late to go back on much of it. They had a totally different (and totally unworkable) plan of how the control room was going to be laid out, as well as for some of the other rooms. They even had wonderful architectural designs embedded into the walls, with interesting geometric shapes built into the framing itself.. But Rod (the owner) started wondering if that was the right track, and contacted me. I had to break the sad news to him that it just wasn't going to work like that, and he would need some drastic changes. Fortunately he was smart enough (and humble enough) to bite the bullet, and allow me to re-design it completely. The result is what you see in that thread. Even though he already had architectural and decorative stuff built, he ripped that down and we did it all over again. He hit "reset" on the project, and today I think he's pretty happy that he did. Feel free to contact him and ask about how he thinks it worked out, compared to how it was going to be in his original plans.
This seems to happen regularly: I've been involved in re-doing a few other rooms as well, even fully-completed rooms that were not working at all acoustically, due to architectural decisions having been given precedence over acoustic decisions. It does happen. And it's very sad when that happens. Telling a client that he basically needs to rip out everything down to bare walls, floor and ceiling, then re-build it properly, is not fun. It's heart-breaking for him, as he has to throw away a lot of time and emotional investment, as well as lose money in wasted time and materials. But the people that decide to redo it properly, always end up happy with the final result, and are glad they made the decision.
Sorry to be so blunt and "in your face" about this, but I'm not one to hold back when I see bad decisions being made in a studio! My intention here is not to insult or belittle, but simply to warn you about the big mistake you would be making by continuing down the current path. So please take the above as a "tough love" reality check. A heavy-handed wake-up call. What you show on those photos is not going to work as a recording studio. It might look nice, it might even get featured in architectural magazines, or win prizes for creative design and decorating. but it won't be functional as a high-end studio.
In your very post you said: "I think i tend to 'overbuild' in some areas and then not pay enough attention to the weak spots". I have to agree...
Fortunately, you are at the stage right now where it really doesn't take a lot of effort to fix, and it won't cost you a lot either. All you have is framing, and that can be taken down and rebuilt right simply. It's a lot harder to do once you start putting up drywall and insulation...
So that's my US$ 0.02 for the day. Hopefully you'll take it in the spirit it was intended!
- Stuart -
I find that REALLY hard to believe! Plus, STC is a really lousy way of measuring studio isolation anyway...