Final advice before I take the $50,000 plunge?!

crowbar0 · Post by **crowbar0** » Fri Dec 02, 2005 10:47 pm

Regarding the floating floors, I was looking at this method on SAE and I think I could do it within my budget.

If I was to frame out my floor space area per room (300sq.ft), then construct the floor as specified within the framing, when the concrete has dried and the framing is removed would the resulting raised structure be strong enough to support my large wooden framing walls?

knightfly · Post by **knightfly** » Sun Dec 04, 2005 8:25 pm

First thing would be to know the strength of your place, and since you don't have one yet it's kind of a moot point. Second thing is, I've never floated concrete on rockwool so don't know how dense you'd need to support the weight - 4" concrete weighs approx. 50 lbs per square foot. If you've read through the REFERENCE section you know how to calculate/measure deflection for any type of rubber under wood floor joists and concrete, which can have better isolation than what you propose simply because of the increased air gap (damped with rockwool of course) - here's a sketch I did for Hugo some time back - speaking of which you need to crop the excess blank space out of your room construction sketch and re-post it; I tried but ran into a really wierd error and lost it... Steve

Post by **sharward** » Mon Dec 05, 2005 2:12 am

Steve, no sketch...

knightfly · Post by **knightfly** » Mon Dec 05, 2005 8:43 am

Yeah, got the Slackmaster on it...

crowbar0 · Post by **crowbar0** » Tue Dec 06, 2005 7:11 am

If you mean the strength of the floor in 'my place' then it will be a solid concrete floor so I dont think I should have any problems with it supporting the weight of the floors.

I've been looking at "Aaronw"'s floating floor thread, and I'm now leaning towards doing something similiar, almost identical in fact.

I think it should provide the isolation I need, and is a lot easier and more cost effective than floating concrete!

knightfly · Post by **knightfly** » Thu Dec 08, 2005 12:40 pm

Aaron is in a HOUSE, and doesn't have (IIRC) ATTACHED neighbors; and if you price sheet building materials, you might be surprised at which is cheaper. A 4x8 section of floor with 2 layers of 3/4 OSB and a layer of 5/8 gypsum would cost around $45 (framing extra), while the same area of floor using ONE layer of 3/4 OSB and 3" of concrete would run about $20 for the OSB and about $25 for concrete - the OSB/gypsum floor, set on 2x4's and pucks, would have a m-a-m resonance of about 34 hZ -

while the concrete/OSB floor, set on the same framing, would have a m-a-m resonance of about 17 hZ.

Bottom line - same price, one OCTAVE lower m-a-m, meaning one octave lower for the same transmission loss...

(Of course, if you ever intend to REMOVE the floors the concrete would make it a bit tougher

) Steve

crowbar0 · Post by **crowbar0** » Sun Dec 11, 2005 3:33 am

knightfly wrote:(Of course, if you ever intend to REMOVE the floors the concrete would make it a bit tougher ) Steve

Good point! All depends on the terms of my lease really.

Just with regard to using neoprene pucks, what is the prefferred method of securing them to the floor, and then securing the framing to the pucks?

Contact cement?

Because if one of the pucks were to move or the framing was to slip it would probably bring down the whole room!

Post by **sharward** » Sun Dec 11, 2005 4:32 am

That was one of the challenges that led me to abandon the concept of floating a slab. Here in California, building codes are such that floating is difficult to reconcile with code -- perhaps not impossible, but difficult, in that it's probably something that would require a waiver from the building department chief once they're convinced the strength and longevity is equivalent or superior to conventional code-defined methods. That's a heavy burden to prove, and one that probably requires a lot of expensive structural engineering drawings to support.