I'm trying to reduce the sound coming up through the floor from the flat
below. It is mainly the low frequency stuff which gets through but get
through it does. The building is a 1930's purpose built flat and the floor
structure is a concrete slab about 150mm thick with a wooden raft on
50mmX50mm wooden battens fixed directly to the concrete floor with a cement
filler. The original floor boards have been replace with 18mm chipboard
sheets some time ago for other reasons. What I want to do is fill the space
under the floor with something to absorb as much of the LF as possible. I am
aware that what is needed is mass. Having read back over various postings
that are still on the server their seems to be two main suggestions. One is
a heavy aggregate such as sand and the other is high density Rockwool slabs.
As the structure of the floor will permit me to use either of these options
I was wondering which one people thought would be the better. I am also
going to add a strip of 5mm dense foam between the top of the battens and
the flooring boards.
Low Frequency sound travels through the main structure of the building, so
just doing the floor will probably not solves the problem. Why not ask the
downstairs neighbour to fit their speakers on cushions. This will also let
them hear better sound quality as well as stop the sounds from travelling
all over the building.
If the problem is them shouting and bawling at each other, then keep calling
the police every time it happens and it will soon stop.
SAND is what you want. Rockwool is perhaps useful for HF, but sand is
better to damp out booming.
However it won't even then make all that much difference to seriously
low freq's carried through the structure.
It will be BETTER, but how much better is a moot point.
Our flat has the same construction and the same problem :(
Most of the transmitted noise is through the walls, not the floor.
If you manage to come up with a solution that works I'd try it ;)
I've already got 18mm chip over the floorboards with another 7mm of
woodfibre underlay then laminate. It attenuates HF very nicely,
certainly can't hear voices from downstairs, does naff all about
slamming doors,windows, etc... :(
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