Steel Stud and RC framing question..

[Travelreview]

I just got through re-reading all the forums' posts, stickies and the entire USG handbook, and I am a bit confused about several wall and ceiling framing proceedures.

Please excuse my perhaps overly novice questions, but I would appreciate any advice from those who have already dealt with these issues during their studio design and construction projects....

I will soon begin the renovation and interior reconstruction of a 1500 sq. ft. former demo studio is located on the second floor of a 4 floor downtown building here in Montreal. I have atttached rough floorplans of the current layout, and a draft of our proposed layout. This new facility will have a digital multitrack recording studio as well as an AVID video edting room, both with 5.1 and stereo capability.

We have determined through comprehensive testing that the existing wood stud single frame walls and single leaf gyprock ceilings in the CR, ISO and Live Room areas do not achive our desired level of TL and STC.

Since the current ceiling (9' 4" high) is just a single layer of 1/2" sheetrock screwed directly into the 16" oc wood floor joists above (uninsulated), and the existing partition walls were poorly sealed and had the wrong density of insulation and low quality gyprock, I assume we must will rip that all down!.

Since floating the floors would be beyond our budget, I suspect that we will at least need to build new double frame interior walls and suspend new twin layer gyprock ceilings on RC for these three areas.

I plan to replace that existing ceiling by first insulating the cavities with a combination of Roxul and OC 703, then attaching a few 2"X8" and 2X10" wood studs to the existing joists to create a 12 degree slope. I would then somehow secure the insulation into the cavities, and add RC stips upon which I would secure 2 layers of 5/8" Type X gyprock.

The current proposed wall construction method would utilize two adjacent steel frames, each using 3-3/8" steel studs of gauge 26 steel, each cavity filled with 3" Roxul Safe&Sound, and a 2" airspace in-between the two steel frames. As per this forum's suggestions we intend to attach 2 layers of 1/2" type X gyprock on 1 side of the interior frame, and 2 layers of 5/8" type X gyprock on 1 side of the exterior frame.

My questions are as follows....

1) Since the steel studs require steel tracks be installed on both floor and ceiling to hold tem in place, should I first rebuild the ceiling as indicated above and then attach the steel studs' ceiling tracks to the underside of the new RC hung gyprock ceiling??? Is there any reasonable way to avoid the new walls and ceiling being coupled as such??

2) How should I best secure the insulation in the existing ceiling joist cavities without creating a third mass up there???

3) There are currently functional HVAC ducts hidden by a simple T bar and acoustical tile suspended ceiling (the former studio had added 4" of OC Pink thermal fibreglass insulation above those tiles) resting 16" below the actual ceiling. If I build the new walls and ceiling, and then wish to reinstall the suspended ceiling to once again hide the HVAC ducts, will this acoustical tile and the 4" of thermal insulation placed atop the acoustic tile create a third mass effect???

4) Am I going about any of these tasks in the wrong way or is there perhaps any alternative methods or design elements I should consider???

5) Have I overlooked anything that I must re-examine? Have I made any basic errors in my design or construction concepts???

Thanks in advance for your help, suggestions and advice....

RON CHARLES
Montreal
Travelreview@Hotmail.com

[Innovations]

Some quick comments.

The route to get from the control room to the live room seems awkward. Either try to work it so there is a door from the control room to the sound lock of use the idea of double sliding doors for the windows between the live and control rooms. If you do that then you can most likely skip the double doors from the iso room to the back room.

You will need to double wall between the live room and the exterior and between the live room and the office. Pay attention to the windows to the outside. if you want the natural light then treat them with an inner window like they were a studio window.

[Travelreview]

Thanks Innovations!.

I agree that the access between the CR and ISO and Live Room via the Soundlock is awkward, and it would certainly be better if there were sliding glass doors between the CR and ISO ( John Sayers also wants me to make that change), but at a local cost of over $1550 USD for 2 new sets of good STC rated sliding doors, it's a bit above my budget capabilities for now. I will search around for used sliders and I will install them if I get lucky and find some at a good price, otherwise I may need to consider that approach in a future upgrade.

In terms of the existing Live Room to Exterior single mass wall, this is a solid 12" thick granite wall and absolutely zero noise penetrates or exits, so I will leave that as is. The existing (sealed!) Live Room to Exterior windows are custom designed 11 mil. double pane argon windows of very high STC and as such I will leave those as there are now.

I will however follow your superb advice and build a double the wall between the Live Room and Office as you suggest (I certainly overlooked that important zone!) .

Thanks so much for your suggestions....

RON

[AVare]

In terms of the existing Live Room to Exterior single mass wall, this is a solid 12" thick granite wall and absolutely zero noise penetrates or exits

That wall has STC of around 52. If you don't have any low frequency noise outside that wall, it will be okay, assuming that you are going to put insulation finish drywall etc on the inside. If not there will be noise problems.

[Travelreview]

Thanks for the reply AVare,

Please pardon my ommision, but I seemingly neglected to correctly detail that granite exterior wall's actual composition when I posted the floorplan and also again when I responded to Innovations' reply!.

The existing granite exterior wall actually is already covered on the interior (except the window areas) by an adjacent single 2" x 4" wood stud wall with a 3" mineral fibre filled cavity and 2 layers of standard 1/2" gyprock. While it perhaps could be improved upon (Perhaps by adding a final 3rd layer of 5/8" gyprock?), I do not think it is absolutely necessary in our case.

We have tested the current exterior wall with third octave tones, pink noise, and a very loud 6 piece rock band (avg C weighted SPL of 116 db), and have had no noticable leekage through either the wall or windows to the street outside. The other good news for us is that even when a huge truck (or a dreaded deisel garbage crusher) passes the street below, there is fortunately almost no measurable rumble or noise anywhere in the facility.

Thanks for your input...

Ron Charles

[dave downunder]

There's some useful technical pdf's on wall construction for fire and acoustic performance here...

http://www.gyprock.com.au/technical/technical.asp

The 'System Selector" on this site (in the pull down menu under "Design") is also useful for checking your design's STC performance.

More useful design pdf's here...

(Link had to be cut into 3 sections to avoid horizontal scrolling. Copy and paste each section into your browser address line to make one long link without any spaces)

Code: Select all

http://www.boral.com.au/brochures/orders/default.asp?
AUD=contractorBuilder&nodes=IC:Plasterboard&toggle
Item=brochures&menuitem=plasterboard&company=Plasterboard

[Travelreview]

Thanks DownUnder Dave,

I had a peek at the gyprock.au site and I suspect I will be using something similiar to wall model CSR275(b) which may yeild theoretical results of about RW 62, which I think should be suffecient for proper isolation between my CR and adjacent ISO and Live Room areas (although the windows are expected to reduce the actual RW and STC and TL ratings to a measurable degree).

Thanks for the great link!

My main concearn is that I am still a bit unsure if I first install the new ceiling (on RC or the Resilient Mounts if I can find them in time) and then attach the upper steel stud track to the newly suspended ceiling, or if I can find some other better method of securing the upper steel stud track to the ceiling (in order to reduce the coupling between walls and ceiling).

Any thoughts???

Ron Charles

[AVare]

The existing granite exterior wall actually is already covered on the interior (except the window areas) by an adjacent single 2" x 4" wood stud wall with a 3" mineral fibre filled cavity and 2 layers of standard 1/2" gyprock. While it perhaps could be improved upon (Perhaps by adding a final 3rd layer of 5/8" gyprock?), I do not think it is absolutely necessary in our case.

With the additional data, I estimate that the STC is in the low 60s and the worst TL down to 62Hz is around 32 dB. Excellent performance! I guesstimated that number from actual tests performed by the NRC and detailed in their IR-586 report. If you are looking at internal wall construction additional testing data on over 350 wall types is in their IR-761 report. Both are available at their website. No need at all to improve the isolation on that wall.

My main concearn is that I am still a bit unsure if I first install the new ceiling (on RC or the Resilient Mounts if I can find them in time) and then attach the upper steel stud track to the newly suspended ceiling, or if I can find some other better method of securing the upper steel stud track to the ceiling (in order to reduce the coupling between walls and ceiling).

At the top of this forum is a link to the USG drywall installation guide. It is considered the bible for drywall installation. It should answer your query about how, the direction is clearly do the ceiling first. It is also full of useful tips and tricks for doing drywall.

I noticed that you are who I posted to about not detailing you location. Now I know you are in Montreal.

Enjoy!

Andre

[Travelreview]

Thanks to Andre for another rapid and informative reply!

I appreciate the encouragement, and thanks for taking the time to look up these massive pdf documents, which I've been poundering over for a few weeks now.

The USG handbook is truely a great resource, and it covers almost every aspect of basic sheetrock consturction one would ever want to know about. I have just re-read pages 76-93 which deal with steel framin and RC & furring, and I have learned plenty of solid information (something I need to know as I have never constructed or designed anything before in my life!).

Unfortunately, it just says to "INSERT FLOOR TO CEILING STEEL STUDS BETWEEN RUNNERS, TWISTING THEM...." but does not offer any detail as to how to properly install a steel stud wall's upper track (runner) into the ceiling whilest obtaining full or partial decoupling of these 2 structural elements. I am sure this has been dealt with before by several other studios that have used steel studs, but I am just too inexperienced to fiqure out the proper method myself!. I am really a novice at all of this.

I have in fact used a National Research Council of Canada's labratory tested design (WALL 345) as the basis of my proposed interior partion wall concept, although I am hoping to take it two steps further than the NRC got to when testing hundreds of wall design combinations.

The superb and in-depth lab analysis online pdf document you mentioned (IRC IR-761 "NRC Gypsum Board Walls-Transmission Loss Data") explains the effects of staggering dual framed wood stud walls, but just does not indicate if there is any improvement that might be gained by either using seperate upper and lower tracks (runners) for each of 2 frames (Page 13 figure 6 indicates that all Steel Frame results were measured using "SINGLE TRACKS AT TOP AND BOTTOM", or by staggering steel studs in similiar walls, such as is shown with examples of double frame staggered wood stud walls such as WALL 290.

I'm not at all qualified nor mathematically skilled enough to know for sure, but I am, perhaps incorrectly, theorizing that if I build a design such as WALL 345 of the above NRC document, and then add the 2 extra bonus construction features of seperate frames on seperate tracks and staggering the steel stud locations, perhaps a few extra db of STC and higher TL rating at low frequencies may result.

Am I totally off target here, or would one or both of these added factors help to further improve the walls' real world isolation???

RON CHARLES
Montreal

[Travelreview]

I just re-read some Kinetics data, and I am beginning to think that they make the products which can solve some of my design issues.
I just read about IsoMax resilient mounts (Thanks threads I read by AVare and DownUnder Dave), KWSB Sway brackets, ARS and ICW ceiling supensions, and a few other interesting items.

I realize these are top of the line products from a very respected company, but I have a feeling that many of these items are rather expensive for folks like me on a relatively tight budget. Are there more generic sources or alternative products/methods (with fairly similiar results) that I should consider incorporating into my wall and ceiling designs?. Is this just overkill in my case??

Ron Charles

[AVare]

Am I totally off target here, or would one or both of these added factors help to further improve the walls' real world isolation???

You getting into uncharted territory. If you want to start to "custom design" your walls, then I strongly urge you to buy the Insul software progrem. It lets you play with many factors in the design of partitions and see the prdeicted results. The demo program does not let you change the material type, which you may may want to do. It is from Marshall Day Acoustics.

I did a quick check with the demo. Adding hte third layer and increaing the spacing by 50% improved the STC by 8 points. The low end TL was still lousy, as all (light weight) walls of this type are.

[AVare]

I just re-read some Kinetics data,...

I realize these are top of the line products from a very respected company, but I have a feeling that many of these items are rather expensive for folks like me on a relatively tight budget. Are there more generic sources or alternative products/methods (with fairly similiar results) that I should consider incorporating into my wall and ceiling designs?. Is this just overkill in my case??

The Isomax is 70% the price of the PAC-International product. The other Kinetics products are considerably more expensive.

Is it overkill? Only you can answer that question. You wrote in your first post that the current conditions were unacceptable after considerable testing. Analyse your test results to determine how much isolation is required. Use TL data, NOT STCs!

BTW, you are getting into some very unique construction designs. Have you checked the building codes to see if what you are considering can be built? Unbalanced double/triple layers, unbalanced single sided. HAve you considered chase walls?

[dave downunder]

My main concearn is that I am still a bit unsure if I first install the new ceiling (on RC or the Resilient Mounts if I can find them in time) and then attach the upper steel stud track to the newly suspended ceiling, or if I can find some other better method of securing the upper steel stud track to the ceiling (in order to reduce the coupling between walls and ceiling).

My suggestion would be to install the wall frames first and secure the upper steel stud track to the underside of the joists - fixing them to the ceiling sheetrock doesn't sound very secure to me.

I'd also fix timber battens to the sides of the joists and the underside of the floor above, and insulate and sheet those gaps in the same manner as the walls. Then I'd hang the ceiling framework in between the walls.

When sheeting, I'd put one layer on the walls all the way to joists, then one layer on the ceiling, then another on the walls and another on the ceiling so the ceiling/wall intersection creates this kind of stepped effect and creates a more difficult path for the sound to follow.



If any of the existing walls are in the right position and are soundly constructed, I'd be inclined to strip them back to the framework, add a second wall or resilient mounts, then insulate and sheet them with your preferred materials. It's really easy to rip stuff down, but costs a lot of time and effort to put it back again.

[Travelreview]

Thanks once again to AVare and DownUnder Dave...

I am greatful for your help in trying to set me in the right direction. I realize that I may be stepping into "Unchartered Territory" and perhaps my naive attempts at improving time honored NRC wall designs may be way out of my league, but my inquisitive nature always seems to make me push the envelope a bit more than is needed.

Now I have recieved your two opposing opinions in this thread. DownUnder Dave suggests the wall frames should go up first, and Andre has indicated he suspects starting with the ceiling is better, and I think both methods make perfect sense! This is the point of departure for my limited design skills and more limited experience, and thus I have no idea which method would be better suited in my case, so please feel free to jump in with any more thoughts or clarifications on which of these methods I should go with!

I have re-checked with a good architect and the city's fire code and building permit departments, and as far as they see it, if I avoid messing with any load bearing walls, and I have used structurally safe methods and materials (the fire dept. inspectors seem to be rather happy with my choice of Roxul and Steel Studs), these specialized designs are generally OK with them. I may nowever need to recheck and modify the fire exit and sprinkler system layouts before submitting the plans they require for the next round of permits.

I have another crazy idea, and another question about the ceilings and walls........................

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?????

If so, could I consider using a wide wooven fine wire mesh to cover the OC 703 (I have seen burlap and cotton coverings commonly used for this in other studios' clouds, but the fire inspector may insist I use fire resistant fabrics such as Guilford of Maine, which are too expensive for me). Would such a fine metal mesh (like mosquito netting or patio door screening) be too reflective???

Ron Charles
Montreal
Travelreview@Hotmail.com

[AVare]

Now I have recieved your two opposing opinions in this thread. DownUnder Dave suggests the wall frames should go up first, and Andre has indicated he suspects starting with the ceiling is better

My mistake. I was thinking of the gypsum installation. Dave is correct. BTW Dave, excellent posts!

I have re-checked with a good architect...

Great!

I have another crazy idea, and another question about the ceilings and walls

Thin light,as in not dense, material like 703 at a distance will not be very flat, or absorbent at low frequencies. If you want to go that route, consider using something like Roxul "Safe n Sound" . The latter is 3" thick 2.5 lb/ft^3 mineral wool. Because of its different market, it is priced at about one fifth of OC 703 by volume! and available at Home Depot etc.
If you want to be more confident in the low frequency effect, double the layers of it. This would cost about the same 1" OC 703, if the prices are similar in your area as mine. WARNING! This is getting into uncharted territory again! Underside support is a cost and design factor regardless. Sorry, no ideas on that one.

Have you done a modal analysis and RT60 design calculations? The ceiling and length in the main room are 1 to 2. At those low frequencies almost no porous acoustic absorption is effective so the sound will see the hard surfaces regardless of what porous material is put on top.
Doing all the ceiling will also make for a very dead environment if you add any more absorption on the walls to control echoes, axial modes etc.