Author Topic: Adding an internal layer to sound proof room  (Read 3356 times)


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Adding an internal layer to sound proof room
« on: December 26, 2014, 10:30:21 PM »

I have a 17 ft by 10 ft professional soundproofed outbuilding at the bottom of my garden. It was originally made by IAC acoustics for a music school as a practise room and I now have it as a drum studio having moved it from the college over the summer when they didn't want it anymore.

The construction is large modular panels for all six sides. Each panel is about 1m by 2m, 10cm thick and has three layers of sheet steel, with accoustic Rock wool in each of the two internal compartments. The whole thing is on rails with rubber mounts on a concrete pad. It has a secondary weather roof with additional layers of rockwool, rockwool in the void under the floor between the rails and a professional accoustic door and ventilation system.

This all works pretty well. If I put on the separates Hifi I have in there the music can be uncomfortably loud in the room, but almost entirely inaudible a couple of feet from the room outside. However, when going for it with the accoustic drum kit there is still some noticeable noise bleed out to 20-30 feet, mostly the cymbals, and at that distance it transmits into the neighbours gardens, which I'm trying to reduce or avoid as a responsible drummer.

I still need to do the internal wall coating to finish the job off, which is currently the plain sheet metal so rather bright and also not very nice to look at. In the process I'd like to see if I can increase the sound isolation a bit more, ideally with a different type of insulator to catch any frequencies the steel and rockwool aren't so good with.

I have about 2-3 cm of thickness to play with, after which it will protrude behond the dado boxing which has the mains and network cabling and waist height. I could pad out the dado, but would rather not if I can help it.

So in general I'm thinking of putting up some thin wooden studs, screwing them into the middle of the metal panels to provide isolation from the panel edges. But I'm not sure what to put over and inside the studs, bearing in mind my budget is limited.

One option is to fill the studs with two layers of accoustic carpet underlay, then put carpet over the whole thing. This has the advantage of damping down the internal acoustics, but I'm not sure it will do much for isolation. That much carpet also wouldn't be cheap.

The other thing that has occurred to me is to fill the void with some light accoustic wool (I have a few bags full), then sheet over with accoustic plasterboard. That would be a lot easier and probably cheaper than the carpet option. I suspect isolation would be better, but it might leave more echoes inside the room though.

I've also vaguelly toyed with the idea of a lined hardboard sheet as a cover and then fill the void with sand. That would give loads of mass for isolation, but would probably end up horrendously messy and difficult to actually get done.

Any thoughts on the best choice, or something else I should consider? Thanks.

Randy S

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Re: Adding an internal layer to sound proof room
« Reply #1 on: January 03, 2015, 04:03:18 PM »
Fill the void with mineral wool and use the sheet rock need the mass to block and you can not leave a hollow cavity. The more mass the better the reduction.

Once you have done this then re treat the room with acoustic panels...

By doing both you should achieve a very noticeable reduction.

Randy S.