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Concrete Plate vs Rockwool Drywall Ceiling
Posted: Tue Jul 15, 2003 4:15 pm
by bolehnggak
Hi,
I would like to know, what if I use concrete plate for ceiling soundproofing? Since it got mass, very airtight, and would support a floor above, I think it would be a better solution.
How much STC is a 12 cm concrete plate?
How is it compared to usual rockwool-double drywall-channel system?
Ari
Posted: Tue Jul 15, 2003 10:25 pm
by knightfly
About STC 45 or so - mass is great, but not everything. Doubling its thickness raises STC about 5 points, depending on the original thickness. There are other factors, but I'm out of time for now. I'll go into this more this evening... Steve
Posted: Thu Jul 17, 2003 6:08 am
by knightfly
Ari, if you have a concrete ceiling that will support a floor above, you can add a couple of layers of Homosote above the concrete, then a layer or two of gypsum wallboard, then underlayment (plywood or MDF) and finally the flooring material, and get STC in the range of 55-60, possibly a little better.
Even with heavy mass, which is good for low frequencies, you still need that "air space" (the two layers of Homosote) and a second layer of mass (the gypboard and plywood and floor covering) in order to get good isolation through the entire frequency band.
The other thing that makes what I suggested above a good way to go, is that the two "mass centers" have different resonant frequencies because of their dissimilarity. This keeps any one frequency from finding a "resonance path" and getting through... Steve