Steel Stud and RC framing question..

[Travelreview]

Thanks again Andre!,

I have not as of yet done the T60 and modal calculations, but this will be done early this week for sure. The actual ratio of the Live Room ceiling to long wall ratio is currently 1 : 2.36 (at 9' 4" from floor to ceiling joists), under which a T bar acostic tile suspended ceiling now hangs rather low at 7' 10".

My only reason for wanting to use OC 703 in the ceilings is that a local supplier is stuck with 20,000 sq ft of 703 FRK and he wants to liquidate as much as I want for well below wholesale cost, and at these prices (about $0.83 CDN/ sq. foot) it seems like I should make some use of it if at all possible. I intend to buy about 38 bails of 3" Roxul Safe & Sound for the steel frame walls from Home Depot here at $0.42 CDN a square foot which is also a reasonable price.

Your point about putting too much absorbtion above the Live Room and CR areas is a very good one, and I agree that this most likely will create an overly dead environment!

I have already sent EMails and left voicemail for the local reps for Kinetics (Master Ltee) and Auralex (Gotham Audio Canada) and Soundtrap to see if they have any good prices on the Resilient Mounts like the IsoMax, and to see if they will be a good option for my CR ceiling and perhaps my Live Room as well. I also will redo the math to see the necessary quantity need for our anticipated ceiling mass load.

My question about using metal mesh instead of fabric for covering OC703 in clouds and other areas still stands, since I know there will be no issues regarding the fire resistance rating of the metal.... Will the metal mesh be too reflective of a covering to use on the underside of a cloud array mounted above my mix position????

The demolishion has begun, and it looks like a tornado ripped through the space. I really love the stress reduction benefits of the sledgehammer work-out I'm getting!

- RON CHARLES

[dave downunder]

Since the entire existing space has a T bar and acoustic tile drop ceiling, does it make any sense at all to salvage the T bar grid and later reassemble this drop ceiling once I have finished working on the actual ceiling above it, and substitute 2 foot by 4 foot panels of 1" OC 703 in the 2 foot by 4 foot grids where the old crappy acoustic tiles were placed. Perhaps adding vertical hangars of 705 and 703 (or horizontal layers of Roxul) in the approx. 12" high airspace above the T bars where possible?????

There seems to be two considerations here - structural and acoustic. Re the structural, if you plan to hang anything off your ceiling, it would be wise to factor this into your resilient mount or resilient channel loading design. Otherwise you may get overloading and lose some flexibility and consequently sound attenuation.

Re the acoustic aspect, you may want to run this by a pro. I notice John uses "2 inch Insulco Fibreglass and covered with hemp cloth" in one of his designs - http://www.johnlsayers.com/Pages/Left_Bank.htm. But he also includes other features like slot resonators.

If you like to experiment and try out new ideas, a more flexible construction system that lends itself to change might be the go. Perhaps a number of anchor points (possibly resiliently mounted back to the joists..?) from which you can suspend framework or objects. Then you can experiment with prototype structures and/or make changes from time to time.

BTW Dave, excellent posts!

... thanks AVare.

[Travelreview]

Thanks Dave,

I will most certainly take your advice and factor in any potential usage of a suspended ceiling (if I end up going that route) into the loads that affect the resilient mounts or resilient channels for the new ceiling. I will call John Sayers this week to discuss the advantages or disadvantages of T bar grid usage, as well as several other issues that I am unclear about such as using wire mesh instead of fabric on the undersides of the cloud array.

I really do appreciate all the great advice from Down Under, Canada and the US in this thread, and I will post any updates and additional queries as I proceed through this strange new territory!.

Ron Charles
Montral

[AVare]

I have not as of yet done the T60 and modal calculations, but this will be done early this week for sure. The actual ratio of the Live Room ceiling to long wall ratio is currently 1 : 2.36 (at 9' 4" from floor to ceiling joists), under which a T bar acostic tile suspended ceiling now hangs rather low at 7' 10".

Start absorbing (no pun, or insult meant) the acoustics you gave read so far. Sound waves reflect off of hard surfaces. They do not reflect off imaginary lines where the bottoms of the joists are. If the top of joists where the hard surface starts is at 11 feet, then that is what the sound waves will reflect off of. If you put porous absorption below that, whether right against the hard surface, against the bottom of the joists, or 16 inches below the bottom of joists in a suspended ceiling frame, the sound will reflect off the hard surface, not the absorber!

My only reason for wanting to use OC 703 in the ceilings is that a local supplier is stuck with 20,000 sq ft of 703 FRK and he wants to liquidate as much as I want for well below wholesale cost, and at these prices (about $0.83 CDN/ sq. foot) it seems like I should make some use of it if at all possible. I intend to buy about 38 bails of 3" Roxul Safe & Sound for the steel frame walls from Home Depot here at $0.42 CDN a square foot which is also a reasonable price.

Start studying what was written to you and what you didn't write!

1"thin light material has irregular low frequency absorption.
Alternative is the safe n sound at about one fifth the price.
You wrote nothing about FRK. FRK is actually bad in this application.

Ignoring the FRK part, at $0.83 you would have to buy 3 layers ($2.49) to get equivalent to one layer of safe n sound at $0.42. Or if you double the safe n sound you are paying $0.84.

The 703 costs 3 to 6 times as much per square foot! You more than pay for what you called top of the line with RSIC and ISOMAX clips with the money you would "save" by not using the specially priced 703.

[Travelreview]

Hi Andre,

Thanks for the great advice!

You have made a good point about the economics of Roxul vs. OC rigid. I was planning to attempt a removal of the backing material from the FRK to make it regular 703, thus I didn't previously mention the OC was actually 703 FRK. I will however use Roxul Safe N Sound for most zones as it is a good product at a very reasonable price and is easily available from many local retailers.

I understand your point about my not including the foot or so of space above the overhead floor joists in my ceiling height calculations, but I however intend to insulate and seal up those cavities, either with a RC hung or ISOMAX hung dual leaf ceiling of gyprock attached below that joist height, so in that case I believe that my previously posted ceiling calculations are still correct at about 9' 4" minus a few inches of gyprock and mounts or RC.

I am beginning to suspect that we have both misunderstood which "Main Room" we were each referring to. Until now I thought you meant the Live Room, but I now suspect you were talking about the control room, which given the ceiling height of 9' or so after installation of a new ceiling at the bottom of the overhead joists, would have been at the ratio of 1 : 2.1 to the max. length of the CR. This actually has been addressed since posting my original draft floorplans by me adding extra length and width to the CR dimensions, unfortunately at the expense of a narrower ISO area. I have also reluctantly added CR to ISO double sliding glass doors as per the strong suggestion of John Sayers and many others.

I have attached a revised draft floorplan, slighly off scale, which I will fully re-draft and post in a day or two with more accurate detail and scale.

Hope that clarifies some of the misunderstandings, but let me know if I am still wrong, as is often the case!.

RON CHARLES

[Travelreview]

Oops,

I finally now see what your were saying about 1:2 ratio in the Live Room, You were in fact correctly explaining that if the exisiting Live Room height is 11' to the floorboards, then 11' is at a ratio of 1:2 to a 22' room width!.

I will however still drop that ceiling to 9' or so using the same methods I intend to implement in the CR (RC or Isomax), thus the ratio becomes a more reasonable number like 1 : 2.4 in the live room. I suspect that is acceptable, but please let me know if not. I also just remembered that these golden ratios do not apply in rooms with splayed walls, so my rambling discussion about the changes I have made in the CR dimensions was foolish of me to even bring up in that context.

Sorry for the misunderstanding about which room you were referring to, I was a bit distracted and I apologize for my error.

- RON CHARLES

[AVare]

Sorry for the misunderstanding about which room you were referring to, I was a bit distracted and I apologize for my error.

Not a problem. The misunderstandings to regret are the ones discovered after construction!

...thus the ratio becomes a more reasonable number like 1 : 2.4 in the live room. I suspect that is acceptable, but please let me know if not. I also just remembered that these golden ratios do not apply in rooms with splayed walls

That is much better. Remeber when discussing golden ratios etc three assumptions made in the theory

1 All surfaces are perfectly reflective
2 The is perfectly symmetrical
3 There is nothing in the room to reflect/absorb/diffuse sound.

So if your room is made of 6" glass surfaces with perfect symmetry and nothing like equipment/furniture/people in it, place great importance on the ratios for best sound performance. As has been written several times, good room ratios at these studio volumes is more to avoid problems as opposed maximizing performance.

For a an depth discussion of room ratios see the BBC RD 1993-08 "Optimum room Ratios..."

[Travelreview]

Thanks Andre for the superb link to the BBC data on room ratios, it was quite enlightening!.

I am still trying to source the IsoMax clips from Kinetics to determine of I will use them for the ceiling insted of RC.


Irregardless of whether I go with IsoMax and furring channels or just regular RC to attach the double layer sheetrock ceiling to be hung down from the overhead floor joists, I need to place my sheetrock order in a day or two to get it to the site on time.

My 4 questions now are......

Should I order the largest size panels (4' x 12') to minimize the quantity of seams that I need to caulk and mud/tape???

Would you suggest the 2 layers of sheetrock I order for the ceiling be the same thickness or different thicknesses (2 x 1/2" or 2 x 5/8" or 1 x 1/2" plus 1 x 5/8")???

I know this next question has been covered to some extent in the forum threads and the USG data, but I am still a bit confused.... When attaching the lower layer of sheetrock to the upper RC or IsoMax/Furring affixed sheetrock layer, what is the suggested method of attachment in terms of the orientation of the sheetrock itself (perpendicular to the first layer?) as well as the recommended quantity and placement and type of screws???

Is using type X fire-resistant sheetrock for this application going to add or subtract TL rates versus using standard sheetrock??

Ron Charles

[knightfly]

Ron, got your PM - if these four are your main questions, I'll see what I can do -

1 - Large panels' only drawback is HURTING your back - other than that, use them wherever possible.

2 - Current wisdom from several sources suggests that differing thickness (other than adding a thinner sandwich between two full thickness layers) isn't worth the confusion of grabbing the wrong thickness boards for the wrong layers, so sticking with 5/8" board in 12' lengths is the most practical.

3 - I stick with just sheet rock rather than punky, flimsy materials that may cause fastener problems and blowouts, with dubious or no improvement in the isolation. Fasteners - for sub layers, use half the recommended schedule - if the full schedule calls for 8" OC around edges and 12" in the field, then sub layers should be at 16" OC around edges and 24" in the field. The top layer would get the FULL schedule, making sure that each layer's screws are long enough to penetrate by at least 3/8" for steel, and 3/4" or better into wood framing. Always put subsequent layers at 90 degrees to each other - also, for walls it looks better to have the top layer running horizontal, because of less seams showing. So if doing two layers, the first would go vertical and the last horizontal. For a three layer leaf, go horizontal/vertical/horizontal. Only the top layer of this three layer leaf would get full schedule fasteners.

Screw types - USG calls the ones for wood studs Type W, and the ones for going into either RC or steel studs, Type S - some of the ones you find at Home Depot just say "for wood", or "for steel studs" - just remember it's the framing that determines the type of screw; you need finer threads for steel, coarser for wood.

4 - Type X rock is roughly 1/8 pound lighter per sq ft than standard rock in 5/8" panels, so would lose a dB or two compared to standard. However, for commercial property you might be better off using the X just to keep the bureaucrats happy.

Let me know if I didn't cover everything... Steve

[Travelreview]

Thanks Steve for the words of wisdom and straight forward advice, it really clears a few things up for me!

I realize you were warning me against using one of the materials in my plan, but I am unclear as to which specific items you were referring to when you wrote....

"stick with just sheet rock rather than punky, flimsy materials that may cause fastener problems and blowouts, with dubious or no improvement in the isolation."

Is it the Kinetics IsoMax or Gyprock brand resilient mounts you are cautioning me about???

Thanks a Million,

Ron Charles
Montreal

[Innovations]

This is what I would do, you save a bundle on sliders and the circulation is much simpler.

[Travelreview]

Thanks to both Innovations and Kinghtfly for more good info and suggestions. As far as Innovations cost saving floorplan suggestions, I am going to discuss this with my Architects tomorrow and try and incorperate some of the ISO booth and CR exit alterations to avoid costly STC rated sliding glass doors. THANKS FOR THE TIP!

Knightfly (Steve) has sent a PM to me regarding some issues discussed here, and I am adding his text below as per his suggestion. He has been a superb source of advice and encouragement (Along with DownUnder Dave, AVare, Innovations, and of course John Sayers, and I owe them all a debt of gratitute. Here is the text of Knighfly's PM to me earlier today...

"On the first (regarding the words "cheap material"), I was referring to mainly "soundboard", Celotex, Homosote, etc, which are basically all the same thing - the only possible use I would make of those materials would be for a perimiter isolation board when doing floated floors, and possibly as a "lay-in" piece between double frame walls around a properly isolated double glass window, to provide a slightly "breathable" cover for the gap between window frames without having to have solid coupling between the two frames. Otherwise, I stay away from that stuff. It's crumbly, low mass, and an extra layer of gypsum wallboard gives more mass with less headaches.

ON the ceiling thing - if you find that you can't hang enough mass for the outer leaf of a ceiling, and want to make up for that (assuming strong enough framing) by using more than two layers for the INNER leaf, I would seriously consider going with the heavier duty RSIC clips and channel - for a double layer, I don't think the extra expense is worth it. For that scenario I would just use regular RC.

Rod and I've talked about staggering studs on double frames, and we agree it costs nothing to do and will likely (gut feel) improve wall performance by stiffening the one side right where it wants to flex the most. I'd go for it.

You don't need any RC in a double framed wall, regardless of WHAT weight steel studs you use - the only time this would come into play is with a SINGLE framed wall - if it's NON load bearing and you are using the lightweight 25 gauge studs, they flex enough to not need RC on either side. For load bearing, heavier gauge studs, if it's a single frame with both sides paneled then you need the decoupling that RC gives. Same with wood studs - single framed wood needs decoupling on one side, period."

Thanks Again!

I am just about to decide on ordering 100 or so of the RSIC-1 clips (Made by PAC Int and Gyprock in Australia), and I will let you all know how well they work with 20 gauge furring for hanging gyprock from the overhead ceiling joists. -

I will also post my Architect's new floorplans as soon as he is done with the math and load calculations...

RON CHARLES
Montreal

[AVare]

Thanks for the update.

An idea that has running through my head ties in with how much isolation do you need between the main live room and the iso booth? Have you considered not having the wall between the iso booth and the sound lock? The room would be a sound lock most of the time, but it gives more space for when it is used as an iso booth. The biggest cost factor would be how much more the door between the main live room and the iso/soundlock room would have to be against how much the wall would cost.

I recall on another site Rod once posted an image from a first class facility where such a system was used.

A friend of mine has a saying "talk is cheap", meaning that it does not cost much at the concept phase, but it becomes expensive to make changes once you are constructing.

[Travelreview]

Thanks Andre yet again!.

Its well past midnight and I have been demolishing walls and suspended ceilings since 5am, so I may not be particularly lucid at this moment!

I understand your suggestion about not walling up a seperate soundlock and instead using the ISO as a soundlock at times when it is unoccupied.

In this case, my concearn about doing that would be not having 2 walls for isolation between the ISO and Live Room when the iso is in fact in use.

Still, it is a brilliant idea and I will consider it when my brain restarts in the morning.

PS- I have got a good deal on the RSIC-1 mounts here in Canada (The $7.50 cdn former price!) and I am asking my architect how to best implement them into the new ceiling design.
My only major problems are that the space has a series 6" steel I beams running just below the overhead joists every 11 feet or so throughout the entire the space, perpendicular to these overhead ceiling joists. This makes flush mounting of either RC or RSIC-1 rather difficult to fiqure out.
Additionally I am having problems trying to plan a 12 degreee ceiling splay because the ceiling joists run perpendicular (not paralell) to the orientation of the desired new ceiling splay. I am sure this is a simple engineering problem, but it is a bit complex for me to wrap my head around at this point. ANY HINTS OR SUGGESTIONS???

- RON CHARLES

[Innovations]

Thanks for the update.

An idea that has running through my head ties in with how much isolation do you need between the main live room and the iso booth? Have you considered not having the wall between the iso booth and the sound lock? The room would be a sound lock most of the time, but it gives more space for when it is used as an iso booth. I recall on another site Rod once posted an image from a first class facility where such a system was used.

Well, having the sound lock and the iso room be one and the same I don't think saves a lot of money, because with the sound lock you need only one door from the iso booth to the sound lock, whereas if the iso booth and the sound lock were the same you would need a double door from the CR to the soundlock/iso-room and a double door between the Live Room and the iso-room and a double door between the iso-room and the entrance. And in my personal experience, no matter how they swing them I have never found a double door on spring hinges that wasn't a pain to use, particularly if I was also having to carry something like an instrument or mic stand. With the sound lock you don't have to be holding the one door open while opening the second.

Ther may be some other minor advantages. One might be that the mics in the iso room are not exposed to accidental damage from people going back and forth between the other rooms. Another thing is that if somebody from the entry carelessly comes into the soundlock it is possible, if they haven't been noisy about it, to not have spoiled something being tracked in the iso room.