Perimeter walls, ceilings and sound insulation

Question

I'm currently planning on converting a basement into a school. It will have adjoining classrooms that need be very well sound insulated and also a reverberation problem that needs addressed.

Having had a builder quote for the work I was surprised at its price. He advised that to sound insulate adjoining rooms we should include acoustic blanket to prevent vibration travelling into and along the cement ceiling and subsequently noise entering neighbouring rooms. Also that this would solve the reverberation problem. Additionally he advises that we insulate the existing perimeter walls for the same reason.

The builder is reputable and was recommended by a family friend. He apparently has extensive experience in commercial and domestic projects. I don't really have a reason to doubt him but:

Is insulation of existing perimeter walls and ceilings more effective in insulating adjoining rooms?

Answer 1

The insulated partition wall is the primary means of attenuating sound transmission. The adjacent concrete structure provides a flanking path for sound to travel around the edges of the partition, so sound needs to be prevented from reaching the concrete. Normally, one only needs to insulate about 5 feet from either side of the partition to mitigate flanking paths. Due to reverb problems, insulating the entire area could be warranted.

Despite all the added insulation, you will still have reverb problems unless the new finished surfaces are selected carefully. Don't forget the floor can also be a flanking path. Carpet and padding will help. Saw cutting the floor slab under the partitions would also eliminate the flanking path, but could cause other problems if the sub-grade is unstable, so consider this approach carefully.