Floor Boom question

[JohnGardner]

I have been reading another post on this and had a question

I am building a floating floor on top of an existing floor that is 20mm particle board flooring layed on timber joists on top of pile/posts 1foot above the ground.

The existing floor is really "boommy" when you jump up and down on it as you would expect with the 1foot gap underneath.

My new floor will be 2x4 on there sides on rubberpucks. The cavity will be filled with R1.8 with one layer of 20mm flooring on top and sealed.

I'm not to worried about the isolation but does anyone think I will still have this boom problem because the existing structure is built above the ground?

Thanks

[knightfly]

It's very possible - resonances are not always exactly predictable, but if neither your outer leaf or your inner one is heavily damped, they will ring at their resonant frequency. You are getting into an area where I'm still learning as well, but from what I understand so far you need a lot of mass and a fair amount of gap with fairly firm insulation fill before resonance isn't likely to be a problem.

One thing that can help this is using two layers of OSB or particle board, the heavier the better, separated by at least one layer of 15mm or thicker gypsum - the different materials, combined with the extra mass, will all work to lower the resonant frequency of the system. Resting inner wall frames and ceiling on the floated floor also adds mass and lowers resonance. This also means, however, that your sub floor framing needs to be pretty strong and that your pucks MUST be centered over the lower joists... Steve