blown cellulose insulation & air cavity between double w

knightfly wrote:

If you followed the link Sharward gave, I posted a horror story

I had already seen the thread long before the hat channel was put up...since it was in the attic's direction it didn't seem worth the effort to remove it. The ceiling ended up as two layers of sheetrock and the attic has around 12" of blown insulation. As near as I can tell, I don't have any sound entering or leaving in the ceiling direction...even with 6 light cans and 2 hvac vents piercing the sheetrock. (I guess with the hat channel, I ended up with more than 12" over that particular room...so I guess it was good for something. :D ) In any event, except for weatherstripping the doors and tuning the room, it's done. I haven't lugged a set of drums up yet for a real test, but a stereo at fairly painful levels was only discernable at the door and in the garage underneath. I suspect if the house were completely silent (no HVAC or TV's running), then you could probably tell something was going on elsewhere...as it was, the ambient noise pretty much masked everything. The wall I was most concerned about seems to be completely silent with an ear stuck to it. I think if I can get the doorway under control (dual doors), I should be good to go. --David

Good to hear it seems to be working for you; BTW, one reason you may NOT be noticing problems from the ceiling with the hat channel - RC does NOTHING for low frequency isolation, it's mainly for mids/highs. So your drums won't likely sound more than a couple dB louder thru the ceiling than they would have using the real deal - your wide air gap is also helping things quite a bit, as will blown cellulose (another couple dB over fiberglass insulation in some tests) Let us know when you get to the actual drum tests... Steve

knightfly wrote:

So your drums won't likely sound more than a couple dB louder thru the ceiling than they would have using the real deal

Probably so, but I wasn't planning to use RC anyway so it seemed rather benign at the time. (Plus that would be in the in-law's direction. :)) Now if it had been on the walls or I had spec'd using RC, then it would have come down.. It is curious there doesn't appear to be any studies on HC usage--I assume it's because it has no audible effect and the RC does have a audible effect.

knightfly wrote:

Let us know when you get to the actual drum tests... Steve

Absolutely.... --David

Yeah, the reason for no studies on HC is that it's considered just a steel replacement for furring strips. Only place you'll see it mentioned in soundproofing is on sites that sell the RSIC clips; those, in conjunction with HC, are actually a bit BETTER than using RC... Steve