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Comment by fragmede | Hacker News Reader

Intrinsically, concrete makes for a far better sound barrier. I'd rather not hear my neighbors, and it turns out using materials that aren't tissue paper really helps! If good fences make good neighbors, sound proofed walls makes it not suck to live on top of someone else.

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Ironically, you can make a better sound isolation barrier using modern building materials than you can with concrete. Mass-Air-Mass. Basically, with a normal “stick built” wall with two layers of sheetrock on both sides, you can get upwards of 60Db of reduction. Make it two decoupled walls (no sheetrock between, mind you), and you can get 80Db. That’s enough to play the drums without waking a baby in the next room.

Oh, and normal concrete walls are outright dangerous in an earthquake of any magnitude. They’re too stiff.

Fill those voids with closed-cell spray foam, and you get even better sound (and heat) insulation.

Except the cells are formed with rigid members which transmit sound (and heat) quite efficiently. Sound isolation can't just be done with mass. There has to be a decoupling you can't get with a brick wall alone.

Even advanced heating/cooling efficiency techniques with wood framed houses involve some form of isolation - no single material will exist all the way through the wall. They're decoupled with several inches of foam. Even modern studs are being built in a way to minimize the ability for them to transfer heat (Tstuds).

Having lived in concrete buildings in Asia, they do an amazing job of transmitting construction noise.

Someone drilling into concrete 2 floors above can easily be heard while in a wood frame building you wouldn’t hear it.

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