John Sayers' Recording Studio Design Forum Archive

Hey All, did a search here and found alot about the pads but when i called to order, from several dif. companies, they all tried to upsale me from standard 60duo 1/2 super W pads 2x2 to a "bridge Bearing" same spec. they all say the others harden over about 5 years leaving them usless

Is this true?
Do I need to go this route?

the reg. Super W Neoprene 2x2 60 duro pad = $2.00 per
the Bridge Super W " " = $5.00 per

Are they tryin to Screw me here or is this correct?

Also, I was told that I should float my floar on these spaces 36" apart on Joists. Then I read here it's more like 24" on joists???? Anybody want to chime in here ???????

Thanks for the help.

jai
www.themixstudio.com

Plywood floor decking is designed to be supported at 24" spans, so if you're just gluing neoprene to the bottom of plywood panels, keep them 24" on center, horizontally and vertically.

Haven't heard this idea mentioned before... I don't know if there's any inherent problems with it. Certainly would save headroom... It'd be tricky to stand walls up on top of it, though; nailing them down around the edge would be risky. Perhaps you could put a bottom plate around the edge of the floor panel, screwed or nailed up thru the bottom, before you laid down the deck. Then you could just tilt the walls up onto that extra bottom plate. But that'd be as much or more of a hassle than just raising the whole floor up on 2x4s....

... just thinking out loud...

If you're supporing the floor deck on joists, 36" will probably be fine, because the joists can span a lot farther than the deck. If the neoprene is thin enough, and you space it out too far, the joists might deflect just enough to touch the concrete between the pads, but that's the kind of thing that'd happen if you spaced the pads 7 or 8 feet apart or more.

It basically depends on the joists you're using. Most of the advice on floating floors that I've seen talks about using 2x4s laid flat, and screwing the deck down to that. Since 2x4s laid flat won't span very far, I'd say 36" would be the very most I'd let them span. I also think that at that span, they'd be fine. Other people may correct me if I'm wrong.

Out of curiosity, is there any advantage to having a floating floor built off of anything taller/deeper than 2x4's laid flat? I mean, it seems like a waste of headroom to me. You could build it off of 2x6s on their edges (like normal floor joists) but why bother, when they'll only be spanning 2 or 3 feet between neoprene pads? If it's built over a concrete slab, then having a greater depth between the floating floor and the concrete (making a greater cavity between the 2) wouldn't help isolation any, would it? I'd think the greater value would be in preserving headroom inside the space...

Again, just thinking out loud.

Kase
www.minemusic.net

Deeper floor joists work in floors similar to walls - that is, the deeper the air space the lower the mass-spring-mass resonance, and the less low frequency sound that will be coupled into structure. Placing rockwool or rigid fiberglas, even "fluffy stuff", in the cavities helps dampen the floor.

I don't have a way of calculating the mass of a concrete slab that's resting on earth, so I can't say just how much mass/distance is necessary to get your floor sub-sonic (lower mass-air-mass resonance than 20 hZ) - Maybe Eric can jump in and enlighten us on this?

Jeff Szymanski (Auralex) recently told me that neoprene typically lasts around 10 years, and EPDM rubber more than twice that. This is why their "U-boats" are made with EPDM. If the "bridge grade" pucks are of EPDM, it's worth the extra. Otherwise, I'd keep shopping.

Kase is right about spans too - flat laid 2x's suck for span. 2x4's on edge on 24" centers, #2 and better Douglas fir, will span 4'5", calculated for 60# live, 20# dead weight - spaced on 16" centers, that goes up to 5'5" - the closer the joist spacing, the stiffer the floor and the lower the resonant frequency. Heavier flooring (whether wood or concrete) for the floated part also lowers the resonant frequency.

All this needs to be calculated so that your isolators are in their optimum compression range with the loads placed on them - generally you want around 25% compression with everything but the people in place on the floor, including any walls/ceilings that will be bearing on the floor. This leaves room for more weight without reaching the point where the isolator is now effectively solid, and therefore useless. Keep in mind that a "spring" is ONLY a spring when it is neither fully compressed nor fully expanded. Beyond that, it is a solid coupling.

Confused? Me too... Steve

If you haven't done so already, there is a lot of info on this thread I have at the top of the forum...

http://johnlsayers.com/phpBB2/viewtopic.php?t=839



Aaron