Home Soundproof Garage - Garage Conversion Stage 4 Soundproof a Room Stage 4 Part 4
Soundproof a Room Stage 4 Part 4

Soundproof Garage

Construction of the outer wall was actually last stage to be completed, but I'll put it in here because it fits at this point.

The outer wall completed with the doors hung and an access hatch to the roof space above the practice room. The holes drilled in the door are to allow air in when the extractor fan it running.

It was at the point when I put the plasterboard on the outer wall that I discovered how much of a problem had been created by mounting the internal ceiling directly to the roof joists of the garage Since I had actually finished the drum room internally before I put the plasterboard on the outer wall. I had already done a few tests to see how well the room was containing the sound of drumming.

From the my house which is about 25m from the garage, all that could be heard of the drums being played was a small amount of kick drum coming through - but it was sufficiently quite that other external sounds would drown it out. Great!

Then I put up the plasterboard on the outer wall, and repeated the tests. Now I could hear snare and cymbals coming through! The plasterboard had actually increased the level of high-mid frequency sound that was escaping from the practice room.

The problem here was that the stud frame for the outer wall was connected to the ceiling rafters of the garage. Also the inner ceiling of the practice room was connected to the garage's roof joists. So via the roof structure, vibration was being transmitted into the outer frame. As long as there was no plasterboard on the outer frame, this didn't cause a problem because the surface area of the frame structure itself is very small. In other words, even though the frame was vibrating, it didn't have enough surface area to cause much radiation into the surrounding air.

Now I go and mount the plaster board on this outer frame and this create a sound board. The vibration in the frame could now be radiated very nicely into the surrounding air!

@~#*&$@ Swear words!

After some head scratching and consultation with various acoustic gurus, I decided that the easiest fix for the problem would be not to remove the plasterboard, but to add another layer of insulation to the outer face of the practice room wall, and then line it with fabric. Now, even though the plasterboard is vibrating, the radiation of sound into the room will be significantly dampened by the extra layer of insulation.

Moral of the story? Follow the principles of room-within-a-room construction as carefully as possible, otherwise you will have to either apply a fix, or in the worst case, tear the whole thing down and start again (not a nice option).

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