knightfly wrote:....
Using 1x lumber laid flat for floating a floor - laying 2x lumber flat is pushing it, you need to keep the EPDM rubber pucks fairly far apart to get at least 20% compression, which is necessary for proper spring action. We normally try to keep 2x4's on edge for this, it narrows the contact surface between wood and rubber, so you get better compression without having to exceed the span capabilities of the frame.
Greetings Steve
Have you ever calculated the MSM resonant frequency of a timber floated floor as you describe above?
from my experience incalcualting my floor and the loads upon it I cannot imagien a timber floated floor having a resonant frequency that's at all low enough to be effective.
With a 10Hz natural freqeuncy. 14Hz is no isoaltion, and it's only 2 ocatves above ( 40Hz ) where you start getting any workable isolation at all. Or even higher. I would make an educated but rough guess that because of the lack of mass, a wooden floated floor would have a natural frequency of between 30 and 50Hz. Which means amplification at those frequencies, no isoaltion 1.4 times those freqeuncies, and little isoation until you get much higher
also, the deeper the air/insulation gap (do NOT leave out heavy insulation here, you'll get 'way too much boom)
If you're getting ANY BOOM the natural freqeuncy is too high. We're geting into laying a huge drum skin on the floor here
When I first layed my concrete floating floor, and without walls and ceiling, I could make it boom easily in the 30 to 80Hz area by jumping on it. It sounded awful. This is becuase it's natural freqeuncy at that time was around these freqeuncies. Now I've built most of the walls and ceiling it's natural freqeuncy has lowered to almost design spec, and now when I jump on it I can feel it vobrating but I can't hear it boom. I would guess it's current natural freqeuncy is about 15 to 20Hz. Once I've got all the ceilign and wall layers installed,and put the soffit wall and speaker system inplace ( again very heavy ), plus the furniture, and equipment the natural freqeuncy will end up where it's supposed to be. Around 9 to 10Hz.
the lower the mass-air-mass resonance of the floor (heavy top leaf helps too) - ideally, you want the m-a-m resonance to be as low as you can get it, 10 hZ would be nice but that takes a floated concrete slab that's about 4" thick over a 4-5" damped air gap...
....
You can get down to 10Hz with a 2" Airgap and 4" concrete slab easily. I did it
Actually I used a 5" slab, but I calculated I could do it with a 4" slab
Laying a wooden drum skin on the floor may give more isolation at higher frequencies, but at the expense of AMPLIFICATION of the bass, and a resonant panel in the studio doing god knows what to the room acoustics.
Personally I wouldn't bother floating the floor. Unless you make the ceiling of your basement EXTREMLY Isolated, then even a properly done floating floor isn't gonna make much difference. Eric Desart always says the balance of the Isolation systems should match up, and he's right.
Just like my floating concrete floor wouldn't make much sense, if I was only using a couple of drywall layers on the walls and ceiling.
Floor insulation: Instead of Rockwool, there was some stuff that looked like styrofoam (it probably was) that has foil on each side. Can that be used?
NOT with a floating floor system. The styrofoam stuff you mention IS used for floor insulation, but is very stiff and can support very high loads. but it's no good for decoupling. Rockwool type insulation is used to fill the airgap inbetween the rubber blocks in floating floors.
Hope that helps
Paul
