Floating floor question n° 2

The Niz

The Niz

New member
Dear all,

I'm not 100% sure on what to do: I'm constructing a floating floor in my humble little home studio (on my attic - see my previous post), and I'm wondering what I should do with the remaining gap of 15mm between the floating floor and the brick wall. See attach for a drawing of the problem.

My first idea was to fill it up with "Isofix" sound isolation foam, but I'm not sure whether that's the best thing to do as to get the best soundtreatment results.

My second idea was to leave it like it is (air gap), because I'll construct a wall on the floor (as box-in-box)

But since I still have some fibreglass isolation sheets (Rockwool) left, my third idea is to fill up this gap with Rockwool.

So, my questions: would these 3 ways make a difference at all? And which of these 3 alternatives would give the best sound isolation?

Your comments please.

Greetings,
Dominique
 

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Here's how the "big boys" do it - this will give you an idea of what to do on yours -

http://www.kineticsnoise.com/floatsyst.html

Scroll down a ways, and you'll see a drawing of a floated floor with "Perimeter Isolation Board" around the floor - this can be Homasote, Celotex, Soundboard, or any other brand of soft, crumbly paper board. The idea is no HARD contact with walls, while still keeping the floated floor from shifting.

You would install the soft board, caulking on both sides with acoustic rated caulk. Then, for the walls - you already have one layer of mass, as in BRICK - next, your wall frame can be either wood or steel studs, but with 2 layers of sheet rock ONLY ON THE INSIDE of the studs - fill with insulation, and you're done.

Ceiling - there are several ways, how much headroom do you have? ... Steve
 
Thanks Steve,

So if I understand you correctly: it would be better to fill up the empty gap -without making hard contact to the walls- to keep the floor from shifting.

So is it correct to say that filling it up with this rather steady Iso-foam would be an improvement rather than leaving it empty? Plus that it will keep the floor from drifting towards the wall.

For the headroom: I've got about 30 to 40 cm that I can use.

Greetz,
Dominique
 
You understand me perfectly - except that I'm not sure what this "Isofix" or "Isofoam" is made of - if it's just acoustic foam, then it wouldn't be firm enough to control shifting of the floor. The stuff that's normally used is like those "acoustic tiles" you see in a grid ceiling in offices - it's 1/2" thick (12.5mm) and looks kind of "worm eaten" on one side, and is semi-hard to the touch. If you want, you can crumble it with your hands. YOu should seal it all around with acoustic caulk... Steve
 
Steve,

OK, I know what material you're talking about. Perhaps I should consider making overtime in the office this week ;-)

GReat, I'll make a decision tonight about what I'll do: acoustic tiles or the Isofoam. My first thought is to use the foam, because it is rather sturdy and I have a lot of it. I'll check the availibility and price of the acoustic tiles/perimeter iso board here in Belgium.

Btw, I was planning on nailing the floor to the underlying studs; this is the way it should be done, no? If I don't do that it will be indeed floating all over the place. If it's nailed, I don't see any harm for structural noise since the rubber pads are under the studs - as long as the floor doesn't touch the wall.

I'll leave about 2 mm opening inbetween the MDF floorboards and fill it up with some silicon filler.

What do you think about this?

Already one BIG THANK YOU for your advice!!!

Greetz,
Dominique
 
Right, you want the entire floor ABOVE the rubber pads to be effectively ONE PIECE - the more mass, the better. Fastening the floor to the joists with nails is OK, but using construction adhesive and nails or screws would be better to minimise squeaks and vibration.

What you do NOT want to do is to nail THROUGH the rubber into the floor BELOW the rubber - the nails would "short out" the rubber and negate most of your efforts.

Using fairly heavy insulation between the joists of the floated floor helps the sound attenuation also... Steve
 
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