AUDIO POST facilities - How to finish up walls with doors?

Hi guys, I'm almost done with the construction of my new studios, but I need your professional opinion and advice on how do i finish up (close up) the walls where the doors are? My walls were built such that they do not touch each other physically. In the following pictures, you can see that there is a gap between the ending part of the walls (it's black in colour because there are no lights coming through the gap) some walls have two doors (wall_door 1 & 2) and some walls have only a single door (wall_door 3 & 4) Any suggestions would be greatly appreciated! Thanks! Regards, [Charles]

Hi again, I thought the reason I get no response to my call for help is because I forgot to follow the forum rules to have a write-up and intro. However, I really need some advices URGENTLY, so if you are in a hurry, please skip this intro and let me know what's the best way to finish up the gaps in the wall. ok, here's more info about the construction: We are an audio post production facilty. Our main work are audio post work for television programmes. Occasionally, we do music / song recording, but because my previous place is not exactly sound proofed, I can only run such sessions late at night. We share the same building as a Film / TV production company. They handle the visual works (production, filming, editing) and we do most of their audio post work. Since we are in the same place, many people think that we are the same company, but we are actually two separate and difference companies. Thus, I actually wanted a separate entrance to my place. But in the old place, we have to share a common entrance with the video editors, thus it still looked like ONE company from the outside :( previously, I wrote a thread on my intention to upgrade my facilities (one year ago). the old thread could be found here: [url]http://www.johnlsayers.com/phpBB2/viewtopic.php?t=4385&highlight= [/url] During that time, I have not decided if we should knock down some walls and expand the existing rooms, or live with it until we find a new place. one year later, we (the video guys and us) decided to move and get a bigger place. This time, we have separate entrances, but once inside the facilities, we can still walk into each other's offices :) For my audio post production side, I have: 1. control room A - 5.1 Surround capable (Pro Tools HD) - (abt 14' x 17') 2. control room B ( abt 10.9' x 7.7') 3. Recording Booth A (abt 14.4' x 7.8') 4. spare room / Recording Booth B (abt 6.5' x 7.7') Construction started sometime late May 2006, and all rooms were built by end June 2006. As usual, money is tight, so we try to DIY the remaining stuffs ourselves. We spent some time (more than two months!!), trying the DIY our own sound absorption panels. Part of the equipment is still not setup/bought because of $$. Some jobs have to go on, so I set up a room B with some packing foams on the walls and our old equipment (Pro Tools LE ...) quickly to cater for that. Now, I have a bit of time, and we have a potential small piece band recording job, so I need to finish up the walls quickly! =============================================== Now, to continnue from the pictures above, here's the picture at the bottom shows how the interior of the walls were constructed. This wall is actually for the smaller control room. (wall_door3 &4) from above post. It consist of two sets of walls that are separated by a 2" airgap. I finished up the end of the walls with 1/2" plywood, but left a small gap so that the plywood doesn't touch each other. This is my Control Room B. Control Room A is constructed something similar to this. At the moment, both Control Rooms have a single door only and it sits at the inner wall. When i add another door to these rooms, it will sit on the outer wall. The other 2 pictures (wall_door1&2) have four sets of walls and look a bit like the jpg picture below. the other two walls are something like a mirror image of the above two walls. and this is my recording booth A. Control Rooms A & B are not floated, but the Recording Booth A is floated with Mason neoprene) rubber pads, 4" x 2" x 8' (long) studs, four layers of rock wool in between (mixture of high density 120 kg/m2 and lower density 40 kg/m2), and then 2 layers of 1/2 " plywood on top, and finally carpet over it. (I'll post pictures of it if you want, but it's constructed just like the other guys in this forum) So, now, back to my walls.. should I fill this gap between the two plys with silicone or chalk it up and then paint over it? another idea I have is to stick something to it (coloured laminated paper, another thin ply or carpets). But sound might still leak out from the small gap in between the 1/2" ply The purpose of this finishing is to make it look good and also to prevent sound from escaping from the little air-gap between the ply. Please advice! Thanks & Regards, [Charles]

hmm, 3 leaf wall ? :evil:

Ro wrote:

hmm, 3 leaf wall ? :evil:

3 leaf?? anyway, here's 2 more picture of the interior of the walls before the 1/4" plywood over it (actually the plys are 1/4 " not 1/2" as mentioned previously). The closed up view was actually taken when these walls are not completed. there is supposed to be one more set of walls in the green circle area. The other picture shows the complete 4 walls. and the jpeg is a cross section of how this 4 walls looks like And with the combination of floated floors and the "french doors" (white doors) with air-lock feature, the sound isolation is fabulous. And it works best when in pairs (ie. 2 door system with each door sitting on different sets of walls that are not touching each other physically) Not sure if you guys have those huge compressor type of air-pressured nail guns used by construction workers.. With the motor blasting away right outside the doors, we cannot hear it inside the room. and when the nail guns are blasting away on the walls, it is hardly audible inside the rooms. Imagine a gun firing away, sound like a tiny hit on a nail. I've yet to measure the actual STC of the walls, but with the above combination, outside noise was brought down greatly! Now, would somebody be kind enough to recommend me a solution to my original question?? Thanks so much! Regards, [Charles]

Jumpin' jehosephats! 5 leaves?? :shock:

Now, would somebody be kind enough to recommend me a solution to my original question??

I'm almost done with the construction of my new studios, but I need your professional opinion and advice on how do i finish up (close up) the walls where the doors are?

Fabric, which meets ASTM E-84 fire test if installed directly against another material or fabric which meets NFPA 701 fire test if not installed directly against another material (drapery meets NFPA 701 fire test) OR a fabric which meets both standards... which may be the best in your case since you have air and frame to cover. Your doors should be AIR tight when closed. I hope the packing foam is not permanent... it's a REAL fire hazard. OK time for a wake up call I suspect no one has replied to this thread becuase 1st, there was a lack of info or even what the question was. 2nd from your following posts it's obvious what ever reference material or who's opinion you sought to build these walls is OUT TO LUNCH. Best sound isolation is MASS AIR MASS or MAM Less sound isolation results from triple leaf or MASS AIR MASS AIR MASS This worsens with more air pockets, its a waste of time money and materials to build any other way than MAM. You need to SLOW DOWN and stop building. You should buy Rod's Book, which is posted in the stickies. You should go through the REFERENCE SECTION of this forum, punish your self by reading everything... don't skip a thing and try no to cry. Marc

Well said, Marc. Sorry I wasn't very constructive. I was in too much shock! Ditto everything Marc wrote, times ten.

:shock: :shock: :shock: :shock: :shock: Doah! 5 leaves!? Yeah, everything he said above.

Thanks for your info, Marc ok, if all the above triple leaf & 5 leaf walls are already constructed, is there a way out? (other than tearing down everything and start all over?) There are water sprinklers in the rooms' ceilings and thus i thought i cannot use the traditional 2 leaf wall / ceiling method to isolate sound from travelling from one room to another. (Sorry, this info should have been listed out in my description thread) i'll try and draw out some cross sections drawings to illustrate the wall / ceiling structures and see if there is any remedy to it. back to my original question: sorry for not being specific. I needed a solution to cover up the ending part of these walls where the doors are placed. At the moment, I've nailed 1/4" ply to the end but they are not touching each other from adjacent walls because if they do, then it would connect these walls directly and the whole thing will just end up as one single wall system. I meant to ask, since they are not touching each other, there are gaps (the red arrows in the first post), and these gaps leads directly to the 2" air gap between the two sets of walls, will it defeat the purpose of the double walls since sound/noise will enter / exit the room directly from the 1st layer of wall thru this gap? ie. if i were to cover these with fabric, will sound / noise pass thru it directly? BUT if i use something solid, then it'll connect the walls. So, will silicon seals be a better solution? I can't afford any more french doors now, but when i can, i would like to complete these rooms with a double door system. So for now, only the recording room have double doors. btw, the packing foams for room B is just a temporary solution. Once i get the main Room A completed, I'll make proper acoustic panels for room B. Thanks once again!

ok, if all the above triple leaf & 5 leaf walls are already constructed, is there a way out? (other than tearing down everything and start all over?)

Well... I can't think of one with out some good old fashion destruction. Please note my answers to your questions & concerns move into the catogory of WILD ASS GUESS, because of the way you have constructed. PLEASE take the time to go through the reference section.

At the moment, I've nailed 1/4" ply to the end but they are not touching each other from adjacent walls because if they do, then it would connect these walls directly and the whole thing will just end up as one single wall system. I meant to ask, since they are not touching each other, there are gaps (the red arrows in the first post), and these gaps leads directly to the 2" air gap between the two sets of walls, will it defeat the purpose of the double walls since sound/noise will enter / exit the room directly from the 1st layer of wall thru this gap? ie. if i were to cover these with fabric, will sound / noise pass thru it directly? BUT if i use something solid, then it'll connect the walls. So, will silicon seals be a better solution?

Well................. hmmmm........... We do try and keep leafs decoupled, no hard contact with each other but it seems you've built your self into a JAM so with out going the destructive route using a slightly flexable material will help the situation. The use of RC on single frame walls adds isolation value while 2 leafs still have hard contact. You could use acoustic caulk, maybe silicone like you say or a wide peice of rubber, anything that's safe to build with that will flex so that as little flanking as possible will happen. You should really get Rods book, I'm looking at a page 94 in the book right now. This shows a single "super" door in double frame assembly, cross section. The 2 walls are slightly coupled with the door jamb assembly, but the gap inbetween walls is sealed shut using 1x4, 1x6, compressed rockwool, backer rod, caulk, 5/4 wood jamb and other materials. I am not going to copy the diagram or make a drawing of it for you.... it's your best answer. Over all we do not want to couple leafs... but sometimes we must and having as little hard contact as possible hurts isolation only slightly. IN regards to your ceiling. Basic isolation is that all walls, ceiling and floor should have the same isolated value in STC and TL. The total isolation is only as good as the weakest link. You could build a wall say with 10 layers of 5/8" drywall, 5 foot air space filled with insulation and another wall with 20 layers of drywall and IF your ceiling had the equivilant of 1 layer of drywall then that's all you got for isolation... 10 drywall layers, 5 foot of air and 20 drywall layers would all have been wasted time and money. Ceiling has to match walls. Hopefully you'll come up with a remedy, or live with what could have been MUCH better. I suppose next your going to tell us your not building on the ground floor. I realize I may sound sarcastic, I'm trying not to be mean or rude BUT you've sent some of our forum members into shock. We've never seen a 5 leaf wall built before. Got to ask to make sure... are you kidding us did you really build this? BTW your not looking for STC value, your looking for TL @ a low frequency. Please do a search for TL if you do not know what it means. Marc

guitardad72 wrote:

I suppose next your going to tell us your not building on the ground floor.

Erm, yes more shock. I'm in a light industrial building and I'm on the top floor. :twisted:

I realize I may sound sarcastic, I'm trying not to be mean or rude BUT you've sent some of our forum members into shock. We've never seen a 5 leaf wall built before. Got to ask to make sure... are you kidding us did you really build this?

Yes, it's already been built. come listen to the rooms if you guys are ever in this part of the world.. hopefully by then I've completed the rooms and even if it doesnt sound good, at least i hope it'll look nice. The following is the top and front cross-section view of the construction. Do note, there were some changes to the layout since the front view jpg was drafted. previously, the recording booth (A) was sandwiched between the two control rooms, but later i thought i needed a bigger booth, so control B became smaller and to the side. Please take a look for more shock :twisted: [/quote]

wooooo weeeeeee Did you already place those hangers with plywood and rockwool up above ceiling frame with drywall? I hope you haven't built ceiling frame yet :cry: Did you know regular unfaced fluffy fiberglass (in US called R13) meant for 2x4 walls is only a slight loss in STC/TL compared to rockwool when used in a wall (not for DIY acoustics though) AND is much cheaper. Did you happen to use backer rod or caulk around perimeters of drywall? I take it all the red in "front view OLD" is PVC for sprinklers? Looking at these pics now makes me think (if your not going to get destructive): Audio A & B, temp record B doors- just use drywall to seal up with hard contact between 2 leafs, unless keeping sound out of the hallway is important. Maybe use acoustic caulk and or rubber behind drywall. Recording A door and windows- drywall between the 2 most outer leafs each side with real hard contact. Fabric in the middle air space if there is one. I am really wild ass guessing hear BUT so much of you construction is not the recommendation anyways. Coupling the 2 leafs won't hurt that much in isolation loss and it does not appear that sound traveling in those directions will effect another room besides hallway. Sound traveling in those directions will end up kinda with just 2 leafs. With the 5 leafs, by hard connecting the outer leafs you'll be working only slightly towards a 2 leaf system, which may make things better. Oh ya... an improperly floated floor will make isolation worse, it will act like a drum head an amplify sound. Properly calculating a floated floor is difficult, to make it effective and not short out the neopreme. I'd love to see some pics of what current existing conditions are. Also you've obviously decided to not splay walls and go square/parallel around. Marc

indeed more shock... parallel walls! The only "good" wall seem the one b'tween the Audio-B and the Aux rooms (according to the 1st pic). Why did ya plan a floating floor in the control room ? and why not in the recording room ? (esp. where drums are set up) Like Marc suggested. Read them stickies, and read'm again. In the meantime let mr. postman deliver you a copy of Rod's new book. THEN consider your plan again. good luck! (as you might have noticed, your plan is flawed. too bad you find out about this website far to late! but hang on, you're in the right place. but get your info updated first, right here on this forum)

Firstly, thanks to all you guys for showing your concern!! really appreciate it!! Next, the walls were built with "general contractors", who built "general" office partitions everyday.. Thus, i do not exactly have confident that they will be able to build the "2 leaf" system properly. Therefore, to be safe and to make sure there is no obvious direct path for sound to go through the walls, I have more gypsums, more air gaps, and more sets of walls (ie. 3 leaf / 5 leaf systems) as i can afford. Anyway, the rooms are already built. What's left are the holes / gaps from my initial post, and some more absorbers, and maybe the ceiling clouds...

Did you already place those hangers with plywood and rockwool up above ceiling frame with drywall? I hope you haven't built ceiling frame yet

sorry once again for misleading information. The front view jpg was an old initial idea. The ceiling hangers were scrapped. The window to AUX / Recording Booth B was scrapped too. The jpg was meant to show the cross section of my wall / ceiling ideas. The final design layout was according to the top view jpg.

Did you happen to use backer rod or caulk around perimeters of drywall?

While supervising the construction, I made sure every layer of gypsum and all holes were caulked.

I take it all the red in "front view OLD" is PVC for sprinklers?

The red pipes are actually metal / brass water sprinkler pipes. There's a picture of it below. ** btw are my pictures too large for the screen? should i reduce it's size?? Anyway, these pipes are one of (the many) the weak point of the design. We cannot substitute them with fire extinguishers, so they have to be there. My only remedy is to change them to those concealed type where all we see from the room is a plastic cap, but whats above are these water pipes and they actually links to all rooms, so it is a carrier of sound / vibration. Anyway, the following are pictures of the floating floor building progress, and also corner traps (full height sealed triangular shaped at all four corners of the main audio room) *** btw, i think the terms i used here is confusing also. When it reads "RECORDING A" in the jpg, it actually means "Recording Room / live room / tracking room ..." where I use mainly for VO (Voice Overs) jobs and occasional band recording. when it says "AUDIO A / AUDIO B", it actually means "CONTROL ROOM A / CONTROL ROOM B" where the sound edits / mixing are done.

With the 5 leafs, by hard connecting the outer leafs you'll be working only slightly towards a 2 leaf system, which may make things better

Actually, I've been thinking about this triple leafs / 5 leafs error I made. So by connecting two sets of the walls together, i might be able to convert it back to the traditional 2 leaf system?? **** what I meant by one set of wall is : Gypsum + Gypsum + C-channels (Studs) + Rock Wool + Gypsum + Gypsum ok, here are some more pictures. (hopefully it's not too shocking..)

more pics

For the love of all that is holy, STOP BUILDING and get a STRUCTURAL ENGINEER over there IMMEDIATELY to make sure you haven't overloaded that light industrial TOP floor of that building! LIVES ARE AT STAKE: yours, your customers', and your neighbors'! :shock:

12.5 KN / M2 :D

Is that good? I can't convert that to our dumb non-metric measurement system. I'm concerned about the CONCENTRATED LOADS, you're imposing on that floor along your QuintaWall (Patent Pending I'm sure). Every linear foot of that five wall, ten drywall layers system has got to weigh about 200 pounds. Every ten linear feet is about a ton. And that's just drywall on the walls, not the ceiling or floating floors.

** btw are my pictures too large for the screen? should i reduce it's size??

YES PLEASE go back and replace/re size pics to max 700 pixels wide, if needed cut the picture in two. I didnt say anything before as I was both shocked and fascinated. BTW, hangers and any acoustic items go in the room to effect the room acoustics, not above an isolated ceiling or other side of wall. Someone else recently made this mistake in a plan too.

So by connecting two sets of the walls together, i might be able to convert it back to the traditional 2 leaf system??

Not completely, but in your case I don't think it will hurt. Got to run Marc

12.5 KN / M2 works out to about 284 PSF; and I wouldn't panic too much about 5 leaf walls either, now that they're built - do a google search on triple camden bbc for more on this. Please note that this is NOT, repeat NOT, the most efficient use of time and materials but it's been used for quite some time, and actually has one possible advantage over a 2-leaf wall - I'm gonna let you read the 2 or 3 pertinent articles that this search will bring up and see who comes up with the particular advantage this system has over a 2-leaf one :twisted: I've done some sketches on ways to cover wall gaps without bridging - check the stickies, they're in there somewhere. Oh, and please resize the pix as requested - it's 4:15 am here, I'm bone tired and having to drag the freakin' scroll bar side to side reading this hasn't improved my outlook much :evil: On the up side, hopefully this will cheer you up a bit Charles :wink: ... Steve

I've resized the big file to 700 pixels wide. Any opinions on those low quality photos (taken with a phone with camera)? should i make them smaller too? i think they're slightly larger than 700 pixels wide now.. Anyway, thanks once again for chiming in. And thanks, mod (Mr Knightfly) for the encouraging articles!! btw, is the gap sealing drawing the one found here ? : http://www.johnlsayers.com/phpBB2/viewtopic.php?p=22297 ============================================= Regarding hangars in the ceiling.. (although I've scrapped the idea of hanging them), please correct me if I'm wrong.. one of it's purpose is to make the area trap some bass / low frequencies, yes? well, since low frequencies are not directional, so doesnt it mean it can be placed anywhere? and since those area above the roof is not utilised, can't it double up as a giant bass trap? (which I would need to control real low frequencies) certain frequencies (low) have huge wavelengths, and thus need an equally large amount of space to trap it. Audio A (Control Room A) will be used mainly for 5.1 mixes, and thus i need a way to trap the low frequencies (from the subs) before it starts escaping the room and get into the Recording booth and other rooms. Initially, i wanted to make those full height corner traps like a helmholtz resonator, with tight sealed trangular boxes (sealed from ceiling to wall and floor). The plan was to seal them up and tune it to trap low freq with drilled holes in the "membrane". from my understanding, the more holes there are, the higher the frequncies it will trap. But after sealing them, and did a quick measurement of the room (before and after), i realised that i have an increase bump at around 30-35Hz. It is something that would not affect normal audio productions, so I'm still deciding if i should find ways to tackle these frequencies. and since the lower the frequency, the larger the wavelength, and thus a larger bass trap is needed. since those corner traps are already built and sealed, and since it tackles other fequencies, i just leave them there and not drill holes to widen it's frequency response. Higher frequencies are easier to treat (with absorbers). It's low frequencies that I am having a hard time with! I can't remember the exact measurement formular, but according to those calculations I did last time, in order to trap 30-35hz, I need a trap that would take up more than half my room floor space !!! So one solution was to place those hangars up there again (as initially calculated). But since my ceiling are sealed now, it will be a hassle to break it down!! And if you look at the way our ceilings are built, and mentally rotate the structure 90 degrees, it actually resembles the walls, and so I think you can look at ceilings like you would look at walls, and apply those leafs principles to it, which means hangers can still be in there.. no ?? ok.. now, back to sealing the gaps in my walls...

That's the right sketch, although the one with the modified moulding would actually need a wider "heel" on the moulding for stability. The general idea for both double doors and double windows is to vent the space between the leaves INTO the inner, insulated wall area for a bit of added absorption, thereby slightly improving performance of the door or window. Ceiling - if it's already built, what do you propose to do about it? Here's the thing - optimum use of materials and space for walls is, as stated several times just in this thread by several people, mass-air-mass. So if you were to use just ONE of your air gaps in the ceiling as a bass trap, it probably wouldn't change isolation much - ideally your ceiling should be filled with fluffy, non-backed fiberglass and then several vents (think of a heat register for example) placed around the perimeter of the inner ceiling - this, because the highest SPL of modes will be at corners whether it's wall/wall corners or wall/ceiling corners or whatever. Placing vents at these positions so that the bass can enter the cavity and be absorbed is a good way to utilize ceiling cavities, assuming you already have a 2-leaf barrier OUTSIDE of this. Please understand that even degreed acousticians are VERY hesitant to "guess" what the results of multi-leaf walls will be - the BBC, in true British fashion, (and in my biased Yank opinion :=) simply built more walls until the problem went away. I hope this helped, I just got off 12-hour night shift so probably missed (or screwed up) a few things... Steve

knightfly wrote:

That's the right sketch, although the one with the modified moulding would actually need a wider "heel" on the moulding for stability. The general idea for both double doors and double windows is to vent the space between the leaves INTO the inner, insulated wall area for a bit of added absorption, thereby slightly improving performance of the door or window.

If I go with the Celotex and spacer option, will the space created by the spacer still allow sound / noise to enter / exit the rooms with ease??

Ceiling - if it's already built, what do you propose to do about it?

Actually, since its built and money is tight, I shouldnt be tearing it down and rebuilding it. But, later on if the concept to make it act as a giant bass trap and if it works out to be cheaper and more feasible to trap my 30-35hz issue, then i might consider breaking it down and add those hangars .. but i'm still not sure if hangars can be tuned to absorp such low frequencies..

...because the highest SPL of modes will be at corners whether it's wall/wall corners or wall/ceiling corners or whatever. Placing vents at these positions so that the bass can enter the cavity and be absorbed is a good way to utilize ceiling cavities, assuming you already have a 2-leaf barrier OUTSIDE of this.

this seems like a good concept. I'll think about this IF i decided to break the ceiling and redo it (when i can afford it..)

Please understand that even degreed acousticians are VERY hesitant to "guess" what the results of multi-leaf walls will be - the BBC, in true British fashion, (and in my biased Yank opinion :=) simply built more walls until the problem went away.

my initial intention was to build as many walls as I can afford (finacially and when the physical space allows), so that if sound / noise escapes from one layer, there is another layer to trap / block it before it gets into other rooms!

I hope this helped, I just got off 12-hour night shift so probably missed (or screwed up) a few things... Steve

I really appreciate you taking the time to go through my issues and I really hope it's money well spent.. more later.. Thanks!

"If I go with the Celotex and spacer option, will the space created by the spacer still allow sound / noise to enter / exit the rooms with ease??" Not sure I understand the question - keeping the "cover" porous to some degree is predicated on using full double framed walls and double doors. The "vent" allows any sound waves that get BETWEEN doors to be distributed into/out of the cavity between walls, which (theoretically) lessens the transfer to the SECOND door compared to using a SEALED cavity (when both doors are closed, the air space between them would be a sealed space if not for it being vented into the surrounding walls. Or did I miss what you meant again - looking at my sketch, it might not be obvious as to what components of the wall have been left out... Steve

knightfly wrote:

"If I go with the Celotex and spacer option, will the space created by the spacer still allow sound / noise to enter / exit the rooms with ease??" Not sure I understand the question - keeping the "cover" porous to some degree is predicated on using full double framed walls and double doors. The "vent" allows any sound waves that get BETWEEN doors to be distributed into/out of the cavity between walls, which (theoretically) lessens the transfer to the SECOND door compared to using a SEALED cavity (when both doors are closed, the air space between them would be a sealed space if not for it being vented into the surrounding walls. Or did I miss what you meant again - looking at my sketch, it might not be obvious as to what components of the wall have been left out... Steve

Hi again, Sorry for not responding, was trying to find a speaker wall mount bracket for my 5.1 speakers (Genelec 8040A).. anyway.. not sure if i am clear in what I am trying to seal.. please look at the attached jpg. The holes (all around) as indicated from my 1st pictures from page 1 are those circled in red in this jpeg. only the Recording booth have a two door system. So a porous cover may be fine, but Control Room A (Audio A) and B (Audio B) have only a single door system. Thanks! Regards, [Charles]