Dr. F's studio thread....

Wow! You guys are loud!

Actually, we're not that loud... It's just a 3 peice, gtr, bass, drums and vocals. Drummer doesn't hit that hard too. The meter is very good though, and doesn't do a whole lot of averaging, thus it may appear to read higher than others. Also, I was using the C weighting as opposed to the more common A weighting, so I was getting much more low frequency into my reading than others who use the A weighting (which is really geared more towards speech).

...given the fact that you're coupling your walls to your ceilings

I am coupling the studs to the joists above, yes, but I am not coupling the drywall on the ceiling to the drywall on the walls. I can't afford to build a second ceiling, either in terms of headroom, or budget, and thus if TL or STC has to suffer, so be it.... I might have to re-visit my numbers....55 dB SPL on the main floor, while it would be great, and would put the leakage down around the noise floor for, it just might not be possible. I was getting 83 dB on the main floor, with just the floorboard/joists covered in roxull....no ceiling was present. Assuming my existing "ceiling" (open joists/floorboards) has a performance similar to a single wall with single sheet drywall, it would be STC 34. My ceiling offered a 20 dB reduction, which would be like a single wall's effectiveness at around 150 Hz (According to the NRC research). Now, according to the same paper, a 2X drywall + RC on one side wall will have about 45 dB TL at 150 Hz, which is like a 25 dB improvement over the simple wall. I realize that things like flanking and HVAC can have a big effect on the overall acheived TL. Also, I realize that TL falls off pretty fast below 100Hz or so, except with very thick walls (large air gaps). I know that I will not acheive the published STC or TL curve, as my construction will have more imperfections than a lab speciment (i.e. I have lighting fixtures to contend with). But would it be reasonable to assume that I can get to about 80% of the lab tested result, given some attention to details during the construction phase? Acheiving an additional 20dB loss at 150Hz would be "good enough" as far as I'm concerned.

Are you also going to "beef up" the outer leaf (current ceiling/floor layer) with more drywall? if you are trying to get good iso from upstairs to down, then you should definitely do this.

Hi Dan, I'd like to do this...but need to consult some span tables to see if my joists can handle that extra dead load. It'd be a tough job too, give nall the HVAC running in the joist cavities, they'd have to be pulled out individually, and then the floor strengthened, then put back in. Cheers, Kris

drfrankencopter wrote:

Dan, who makes this 'miracle' stuff? And where do you find it?

i got mine at acoustical material services. http://www.a-m-s.com/locations.jsp they don't have any stores near you though. you are ottowa, right? home page: http://www.taccint.com/miracle.html sell sheet: http://www.taccint.com/UploadedDocument ... uments.pdf this isn't necessarily the stuff to get. as i mentioned, you have to keep an eye out to make sure it dries without leaving holes. but the main thing is to find something ANYTHING other than lepage, and also something in 29oz tubes. you shouldn't pay more than 3 or 4 dollars US per tube. that should be much cheaper than your 10oz lepage. and easier to deal with. hope that helps! dan :)

Thanks Dan.... Actually, I'd be willing to pay a small forture for true "miracle" in a tube! Like, one that you just open it up and the rest of the studio construction gets done, and it soudns great right off the bat..... No AMS locations anywhere remotely close....guess I'll scope out all the various building suppliers around here, and see what I can get. Anyone have good results with silicone caulk, like for tub sealing? Maybe it's not pliable enough.... Cheers, Kris

any of these places close to you? or these maybe ... a place to start anyway

Most of them are in Quebec, but not too far. But, the search engine there is pretty nice, and gave me some more local places to check out, once I typed in "Ottawa". Thanks, looks like it'll be a busy weekend! CHeers, Kris

drfrankencopter wrote:

Anyone have good results with silicone caulk, like for tub sealing?

I believe that's what Sir Woodlock used -- literally hundreds of tubes of it. See this thread from two years ago. Interesting -- Eric Desart thinks all the obsession over caulking every layer is a waste. (At least he did a couple of years ago -- I have no time to search to see if he's changed his tune since then.) --Keith :mrgreen:

That IS an interesting comment from Eric, and worth pondering. He really knows what he is talking about. We often think about sound-tight being equivalent to water-tight, but it's quite a bit different. A molecule of water can travel unlimited distances through cracks (neglecting surface tension), while a sound wave is not a molecule, it is a pressure differential moving through a medium of air. The air itself doesn't actually move very much. However, I don't know that he is considering the possibility of structural movement leading to joint failure. That's why redundancy is a good thing IMO. It can't hurt and it makes me feel better :) but brian ravnaas' experiment with a 2 inch hole in a wall does back up what eric says. A couple of comments on Paul's caulk. Yes $1.50 a tube is better than $14. But remember he is (or was) using 10oz tubes, making the comparable cost for a 29oz tube closer to $4.50, which is more than any of us are paying for a 29oz tube. No wonder he was using hundreds of tubes, 10oz goes quick! Also his caulk was a royal pain to use from his description. Hopefully I'll have a chance to look at Miracle vs. USG head to head this weekend. USG should give a better result, I'm just curious about ease-of-use.

Oh I totally agree with Eric's comments....in fact, that is largely how I am performing my construction. I am only applying caulk to areas that can act as flanking paths, not caulking between the individual layers of drywall. I caulk the sill and header plates, and any exposed perimeters that could act as flanking paths, but nothing else....saves lots of time IMO. Like Eric, I beleive that it is the mass of the combined layers of drywall that perform the bulk of the sound isolation, and even a small void in an inner layer will not erode this effect, however, there needs to be no direct path through the layer (i.e. no crack that penetrates all layers), hence the importance of have at least one good seal. Cheers, Kris

I just posted a question on that thread to see if I can get away with not sealing my "beef-up" materials on my outer leaf. --Keith :mrgreen: