The metal thingy that hooks into frame and bricks...

Sen · Post by **Sen** » Wed May 07, 2003 11:58 pm

...you know how there's this metal thing that you're supposed to connect frame and brick wall with, you have to have it by regulations right?
How bad is this for STC? Does it matter at all? Can we build without it?

Thanks

Michael Jones · Post by **Michael Jones** » Thu May 08, 2003 3:24 am

We call those "tie backs" or sometimes "dead men".
How high is your wall?

One thing you NEVER want to do is sacrifice structural integrity for STC.

Sen · Post by **Sen** » Thu May 08, 2003 2:53 pm

Hi Michael,
My wall is not yet, but will hopefully be

around 12 feet high. The architect I spoke to, says the regulations here allow only 3 metres hight, which is pretty pathetic, but I still have to check on that one.
As I come from part of the world (europe) where the buildings are structured differently, I haven't dealt with frame/brick situation before I moved to Australia. I must admit it looked funny how they first put the roof on and then everything else

...
Anyway, if it has to be done it has to be done. I was thinking of sticking some neoprene rubber around the "dead men"

or something like that to reduce the transmission....

One thing you NEVER want to do is sacrifice structural integrity for STC.

you must be a builder

Thanks Michael....

knightfly · Post by **knightfly** » Thu May 08, 2003 7:45 pm

Yeah, Michael's a builder, a pianist, a civil engineer, and probably at least a dozen other hats if you look close - it's called "I ain't rich, but I still want all the goodies" - At least, that's what I call it when it applies to me - if I won a big lotto tomorrow, there'd be some heavy duty studio builders getting a call and I'd go back to playing at least half as many hours of the day as I'd like to :=)

As far as the "dead men", I've not done this (no brick construction yet) but if you caulked the deadmen thoroughly and treated the entire brick/outer sheath/frame as one "mass", then did an inner frame and only put wallboard (probably 3 layers, with RC if wood studs) on the inside of that frame, you'd have the proper mass/spring/mass construction and should get the best STC for the amount of material used.

If I'm missing something and there's some reason NOT to caulk the deadmen, I'm sure Michael will let us know as he's building a brick veneered studio as we speak... Steve

Sen · Post by **Sen** » Thu May 08, 2003 8:01 pm

Great to hear that some of us are multitalented and we need that..

I have checked out Michaels studio, and it's looking really good.
Michael, I hope you'll get back to this thread and, as Steve said, comment some more on the subject.
Steve, I'm not sure about the theory of treating the brick and outer frame as one mass. There's still some gap between them. I was thinking of having the brick,then a few inch gap, then framed wall with three layers of plaster or whatever, and then the slat/panel wall inside. Similar to what Blue Bear did for his studio. But his outer wall already existed, would that make a difference as to having to fix the frame to it?? Do you only need dead men when it's a new construction?
As you'll probably notice, I'm hopeless with construction....so ...I'll just leave it there and wait for some more comments on this

thanks

knightfly · Post by **knightfly** » Thu May 08, 2003 8:55 pm

Sen, can you put up a drawing showing the relationship of each component of your proposed wall, as exact as possible?

One way or another, you need to keep to the "two mass, one airspace" model... Steve

Sen · Post by **Sen** » Thu May 08, 2003 10:44 pm

Steve,
here's how I imagined the wall construction..Looking from the top to bottom...I hope it's not too confusing...
This way I thought I'd have two mass-one gap design, with the inside frame finished with slats/panels/cloth. So the inside would basically be only the treatment, leaving the triple layer (on RC) wall and brick wall with a gap in between..

THanks

Michael Jones · Post by **Michael Jones** » Fri May 09, 2003 2:02 am

Well, the building codes here require the tie backs on brick to go in every 4th or 5th course, I'm not sure which.
A tie back is a little strap. One end goes between the mortared courses of brick, and the other end gets screwed to the stud.
But it seems to me if you could do a staggered stud construction on the exterior walls, that it would "dis-connect" the outer treatment from the inner. (That's how I'm doing mine.)

Here's a typical EXTERIOR Wall Section:
Sorry its so crude....
That's a plan view; looking down, thru the top.

Michael Jones · Post by **Michael Jones** » Fri May 09, 2003 2:19 am

Keep in mind too that exterior brick is there purely for asthetics and lowered maintanance. Because exterior brick is required to have weep holes along the bottom course, its doubtful that it will aid in STC much at all.
Additionally, it has no load bearing capability (other than supporting its own weight). It doesn't "hold up" the wall or the roof.

I'm using it on mine because I want the studio to "match" the main house; I want the studio to look like it belongs here and wasn't "thrown together" as an after thought.

knightfly · Post by **knightfly** » Fri May 09, 2003 5:52 pm

Michael, as near as I can figure out the ventilation of the brick for moisture purposes should minimise or possibly even eliminate the "multiple air gap" syndrome - I think, though, that given the choice I would use at least two layers of the OSB on the outside sheath, since that and the inner panels will comprise the majority of sound proofing of that wall.

If you have the room, using wider caps and plates (beyond 2x6) will improve the STC a few dB, as will RC. Doing those things might or might not be worth the effort depending on your particular isolation needs - it's just that staggered studs by themselves aren't an earth-shaking improvement over a standard stud frame - about 10 dB with the insulation as you've shown it.

What I've not seen anywhere, is an estimate of STC in a wall with such markedly different mass between inner and outer leaves - gut feel says not a good idea, but "what a wino", as they say... Steve

Michael Jones · Post by **Michael Jones** » Sat May 10, 2003 12:32 am

knightfly wrote: What I've not seen anywhere, is an estimate of STC in a wall with such markedly different mass between inner and outer leaves - gut feel says not a good idea, but "what a wino", as they say... Steve

Well, I'm not going to second guess your expertise, but it would seem to me that the shear number of different media involved would prove to be as beneficial as increased mass of the same media.

I was hoping for an STC somewhere in the high 50's to low 60's. I thought, through some extensive research, that this wall section would get me there. If not, I'm pretty sure that STC would reach or exceede that in the control room, as it truly is a room-within-a-room, isolated from all exterior surfaces including walls and ceiling.

I did dB readings for 2 weeks on-site at hourly intervals before I began the design process, and while nearly all readings were in the 45-60 dB range (weighted C), there were the ocassional peaks of 70-90dB. Sometimes higher, but RARELY.

Designing for the "worst case" scenerio of 90dB of noise attenuation, an achieveable STC of 50 in the constrtuction, would lower my internal noise to low 40's. Right?, and that's worst case. Low 40's is somewhere akin to a library, is it not?

At any rate, its all theoretical really.
We'll see what it actually is after the paint has dried!

knightfly · Post by **knightfly** » Sat May 10, 2003 3:25 am

Yeah, with your situation that construction should be more than adequate Michael - in my case, I have neighbors on one side that aren't smart enough to train their dogs to only bark when it means something, and the neighbor on the other side has a obsessive-compulsive lawnmower fetish - Consequently, I'm designing my new free-standing 40 x 50 x 16h studio so that the outer shell alone (8" Polysteel w/soundlock. 4" air gap, 6" steel studs w/triple layer similar to your inner one ) should reach STC 65-70 - then the inner rooms take over from there. I think I can reach the point in any of the iso-rooms where you hear absolutely NOTHING outside with a rabid metal-head on acoustic drums, and only a barely discernible thump from the control room (unless the speakers are on, of course :=)

At the very least, I'll (eventually) not have to record any more soundtracks for grade B movies with titles like "The Hound of the Baskervilles Ate my Lawnmower, with me on it" - or "The Briggs & Stratton Boogie, in G(rass) Major, with backup vox by Bowser and the Pit Bulls", etc... Steve