Sound proofing / deadening

[Kevin H]

Originally Posted by Thor

Yes, mass also helps, but the concept of two relatively stiff sheets sandwiching a softer layer does create good damping, so do try it because it is a really easy thing to do. You have to use a product with a good tough outer foil layer, not some cheapo stuff.

But isn't adding mass directly to the panel that is vibrating a different approach to suspending a mass parallel to that panel ?

In the first instance you are reducing the noise at the source, because it takes more energy to vibrate a heavier mass (I believe that's why they mount building air conditioning compressors on concrete slabs).

Whereas the second instance - a suspended mass (with a decoupling layer as Philip said) - is good for stopping sound waves travelling further once they left the first panel.

I would have thought the best solution would be both.

As for the Flash-Tac product, it doesn't really meet the criteria to my mind. Firstly the bitumen isn't very thick and isn't very soft as the decoupling layer, not like some sort of foam rubber for example. Also the metal foil layer doesn't seem very substantial, at least not on the product I am thinking of.

Anyway, I've decided to go down the lead route. I already went out and bought some lead sheet last night (15kg/sq m) plus some high strength building adhesive.

I shall report back!