Would like opinions on potential STC of this design... Howdy,
Due to weight limitations, I could only use so much mass in my design. I feel that lack of mass is the weakest link in my plan here. But, it was either do what I could, or not have a studio room.
Room is about 600 sq/ft overall, 11 ft average height ceiling (slanted ceiling). Room within room construction. Outer walls... 2X4 studs filled with 3.5" R-15 fiberglass batt insulation, then one layer of 3/4" plywood screwed to studs, one layer of 1/2" homasote (pressed paper "sound board") screwed down, and one layer of 1/2" sheetrock, screwed down. Then, the inner room frame is to be build with 2X4 studs, filled with 3.5" R-15 fiberglass batt insulation, and then just ONE layer of 5/8" sheetrock only! (I wish I could put more layers on this inner room wall, but I cannot add more weight than this.... everything is on the second story of a wood framed building). The one sheetrock layer of the inner wall will be spaced about 10 inches away from the outer wall all around. Inner room will be "floating", sitting on some strips of Sheetblok. Floor will be decked and floating on some U-boats. Floor will be decoupled from inner room walls. (Overall, the floor and ceiling have the same integrity as the walls described here.)
This room is to be used to track drums. The goal is to keep the sound of the drums from reaching the outside of the building and disturbing the nearby neighbors in this very quiet neighborhood. I am already accepting that there WILL be some sound leakage to the outside, but I guess the concern is how much? Does anyone care to predict what the overall STC of this set-up might be, and predict how much drum sound will leak to the outside? I am hoping it will just be a "faint" sound of drums leaking to the outside, to the point where people inside neighboring houses (houses are about 30 feet away) will just barely hear it or better yet NOT hear it. But, I fear that I may wind up with a situation where the drums are still pretty darned loud outside. Wish I could know prior to completing this project. So far my outer room is essentially done, now about to start on the framing of the inner room.
I am guessing that I will need to "deaden" the inside of the inner room once done to reduce resonances. I have always dreamed about having a nice "live" room to record in, but according to some things I have read, there will be less sound leakage to the outside if the inside of the room is "dead", as opposed to "live". I think I will need all the help I can get to keep the drums from leaking outside. For those of you who aren't familiar with acoustic drums, they are LOUD.... very high SPLs... like shotgun blasts. Sure wish I could have added more mass, but... this is the only room I have to work with, it's either this, or nothing. Any tips, comments, ideas etc appreciated. Thanks!
You are using a strange construction. Why?Does anyone care to predict what the overall STC of this set-up might be, and predict how much drum sound will leak to the outside?
Using INSUL demo to try and get a rough guesstimate, an STC around 58 dB with the TL at 50 and 63 Hz around 20 dB.
The low end of the drums will be quite audible. Midrange and higher will not.
Andre
-----------------Originally Posted by avare
I have started with an existing structure that has serious weight limitations... second story of wood framed building. This has limited me in terms of how I'd prefer to design the construction of the room.
Assuming that the construction I am using is the max weight that can be added, do you have a better suggestion as to how to construct? In otherwords, would you recommend different materials and design for the given weight limit? What might you suggest to improve my situation in terms of design?
Thanks!!!
Put the material you currently have on the inside surface of the outside wall IN the wall, as per John's wall constructon technique detailed on RSD. Build the inside wall with steel studs to reduce weight. If the floor can take it with the steel studs' reduced weight, add a second layer of gypsum.Assuming that the construction I am using is the max weight that can be added, do you have a better suggestion as to how to construct? In otherwords, would you recommend different materials and design for the given weight limit? What might you suggest to improve my situation in terms of design?
BTW: it is confusing when at times you refer to the studio side as the outside and then the outside facing wall as the outside. Similarly in your wall description writing about parts neing "below."
All we have to work with is your writing. Please make it as clear as possible.
Andre
Thanks for the response... much appreciated. Sorry about my poor descriptions... I'll do better next time.
I have considered using steel studs to save weight... but the problem unfortunately is that the inner room will have a 12 foot high ceiling peak, and also a 19 foot ceiling span. (Room is 19' X 30'.) So, I will be using 20 foot long 2"X8"s to hold up the ceiling. I certainly do not want any columns in the middle of the room. Unfortunately, with this particular frame, I don't think steel studs will work... simply not strong enough, plus I don't believe they make steel studs that are 20 feet long that can hold a bunch of sheetrock. I've never seen it anyway. This is why I have chosen wood. Yes, wood is heavy. I already went from wanting to use 12" centers to realizing that 16" centers would save me weight and thus would be better in this case.... etc.
One knowledgeable person once told me that I am trying to do the impossible.... that the overall limits of my room make it extremely difficult if not impossible to achieve very high STCs... mainly due to the weight limits, size and the fact that it is on the second level of a wood frame. But, I am determined to do the best I can because it is the ONLY room I have.
Regarding "John's wall technique on RSD"... I must have missed that... exactly what are you referring to, and where do I find it?
Thanks!
The details that are coming out are frightening.
You are afraid to put a second layer of gypsum because it will supported by the floor, not the top plates of the first floor wall yet you are going to support the 20' span ceiling from the same wall?
Looking a the span table that I have handy, the maximum span for 2x8s with a 10/20 load is 17'2" using highest grade douglas fir.
Have you had a structural engineer vet your design?
Rod:
I am feeling that your input would be great here!
Andre
I am already factoring in that the inner room walls will be supporting the ceiling, which is why these walls will effectively be so heavy. I am not just worried about the sheetrock on the walls themselves, but also the sheetrock on the ceiling as well... the entire combined weight of the whole room, as it sits on the floor. I am looking at the psf load of the walls, WITH ceiling resting on top. Thus, if I go with 2 layers of sheetrock on the walls, it only makes sense to go with 2 layers of sheetrock on the ceiling as well... and thus the walls would not only be supporting the extra rock that is screwed to them, but also the extra amount on the ceiling as well. I'll add that I did beef up the frame of the outer room by adding dual 2X10s running under where the inner room walls will sit, and added a few extra columns directly below which stand on a concrete basement floor. So, the inner room does have some additional support. It's actually a bit more complicate, I'd really need to post some drawings... I will try to see if I can somehow do this next week.
I was just about to do some calculations here regarding this subject. These 2X8s will have zero live load... in otherwords, there will be no one walking on top of them, no snow, etc... all they need to do is support however many layers of sheetrock I plan to put on them (and some R-19 batt insulation). That's all.. nothing more. So, I guess what I need to know is, how many psf of dead load can 20 foot long 2X8s handle when spaced on 16" centers? Maybe I need to space them on 12" centers to handle the load I will put? This is indeed another reason why I do not want to go with more than one layer of sheetrock. It's not like I haven't considered this factor. This is just another one of the "limitations" of this room situation. I can't think of any other way to frame this inner room (19 foot span ceiling), without either having columns, or altering the shape in such a way to rob a lot of cubic feet from the inside of the room. The frame I have designed allows for absolute maximum cubic feet inside the room, and allows the shape I want... with the one structural downside that I have a 19 foot span ceiling.
At this stage, I do have the option of using 2X10s instead of 2X8s (for the ceiling span)... but if I use 2X10s, I will lose a few very valuable inches of ultimate ceiling height.. plus more overall weight too. I am hoping that 2X8s will do the trick, but I guess it will all depend on how many psf of load will need to be added. There are quite a few different factors that I am juggling here... and ultimately, the goal is to arrive at the best combination of everything.
As far as getting a structural engineer to look at this... I have had two different architects and a framing constractor look at everything... I explained my plans, etc... none of them could give me any solid answers. This situation is ambiguous for various reasons. None of them felt that I could not do what I want to do, they felt it was all within reason, but they were all scratching their heads at the same time. This project seems to confuse the heck out of everyone. It's making me quite frustrated because all I want to do is record some music here and this room project is totally draining me. I just want to get it done.
I sincerely appreciate your input. I would be very thankful if you (and others at this group) could see this thing through and give me as many ideas and opinions as possible. I will try to post some pics and/or drawings next week once I am able.
Thank you!
Things are starting to come together. The more detail we have, the better. The drawings will help alot.This situation is ambiguous for various reasons. None of them felt that I could not do what I want to do, they felt it was all within reason, but they were all scratching their heads at the same time. This project seems to confuse the heck out of everyone. It's making me quite frustrated because all I want to do is record some music here and this room project is totally draining me. I just want to get it done.
What are the ambiguous factors? Perhaps if we start with those, we can clarify those and thus move the project on.
With your last post, I fell much better. Several things came out that had me scared. They are resolved now.
What is the construction of the current ceiling/roof? Perhaps double gypsum is not necesary on the ceiling. What is the construction of the neighbouring buildings and the distance to them?
It may seem tedious, but good studios are 90% planning and 10% construction.
Andre
Andre... I'll say it again, I sincerely appreciate your help here. I've actually been working on this room for several years now... on and off (due to scheduling issues)... but I really wish to get it done now within the next few months. I have sought educated opinions about the design and construction of this room over the past few years and have never actually found anyone that was either willing or able to offer any true helpful information... even the architects and framing contractor that I brought in. I had visited other studio construction newsgroups in the past (can't remember which ones now), and never got much useful info from those. Usually just guys bashing my ideas without offering solutions. It seems that you (and other people at this group) have a good attitude and good grip on this stuff and seem interested, so I am indeed very excited to hear your educated opinions and comments. In the next few days, I will make some drawings of everything and will create a webpage to hold the drawings... and will post a link here.
The "outer room" is completed at this point. I feel I have done all I can with it, and the work is done. (Hopefully we do not determine that there are any extremely major problems with this outer room.) With the three layers attached to all walls, ceiling and floor (3/4 ply, homasote and 1/2 sheetrock), the outer room has stood up very well so far, even in almost 2 feet of snow load. No sagging or flexing observed, no creaking, no movement. The outer room (and building) seems to be pretty solid as is. But I do not want to press my luck by adding even more stuff on it (ceiling specifically)... unless the group feels that I could very safely do so. (Note... the weakest link in the outer room is the ceiling which is supported by the roof... drawings coming soon). But in sum, the outer room itself seems ok right now. So.....
What I really wish to study at this point is the best way for me to deal with the inner room and "floating floor", trying to achieve the greatest STC possible while not causing the building to collapse from excessive weight. I guess I really need to just look at the proposed psf loads to be applied and determine if the outer shell (building foundation, etc) can safely handle it. Again, the trick here is to go with as much mass as possible for best STCs... seems that in order to really get things "optimum", I'd need to dial in the exact "maximum" amount of mass that can be tolerated... and that seems a bit tricky. It is always easier to stay on the "safe" side and go with less mass than what the limit is determined to be.... but then I may be robbing myself of much needed STCs... and if I cannot get enough STCs to happen, the room may turn out to be totally useless to me.
Ok... drawings coming soon. THANK YOU!!!! :D
eagle123@optonline.net
Great stuff that you just told us in your last post.
A redirect here:
STC is not suitable for addresing music isolation. Look at the actual TL curves of tested designs paying attention to what is going on from 50 to 100 Hz.trying to achieve the greatest STC possible
These are big documents but they probably have usefull information for you:
http://irc.nrc-cnrc.gc.ca/irc/fullte.../nrcc46396.pdf
http://irc.nrc-cnrc.gc.ca/irc/fulltext/ir811/ir811.pdf
http://irc.nrc-cnrc.gc.ca/fulltext/ir761/
http://irc.nrc-cnrc.gc.ca/irc/fullte.../nrcc44764.pdf
Looking forward to the drawings so we can focus on the issues and avaoid communication problems.
Andre
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