Floor plate isolation products

[RyanC]

For a build with fully independent framing for each room all on a slab on grade, is there any benefit to these types of products?

http://www.acoustiguard.com/products/so ... ation.html

I've also read of putting MLV under the floor plate or Rod's book has wall assemblies that show rockwool (IIRC). My thinking is that if a subwoofer is sitting on the slab then flanking directly into the slab would probably be the weakest link, but if the sub was on a (correctly loaded) iso mount then maybe the next weakest link in the chain would be flanking into the wall and down through the floor?

Any thoughts/tips appreciated.

[Soundman2020]

For a build with fully independent framing for each room all on a slab on grade, is there any benefit to these types of products?

To be honest, not a huge benefit, unless you are going for very high isolation levels. Every bit of isolation helps, yes, but there's also cost and complexity to consider, as well as code. Check if your building code allows you to do that, first of all. Then there's cost. Is it worth your while to spend that money in order to get an extra couple of dB isolation in the low end? For high isolation, the answer might be "yes", but for typical isolation, probably not.

but if the sub was on a (correctly loaded) iso mount then maybe the next weakest link in the chain would be flanking into the wall and down through the floor?

Unlikely, considering the relative masses of the wall and floor, and the direction of vibration. The weakest link would be into the wall, across the cavity, and out through the other wall. The pad under the wall won't help much with that...

But yes, an isolated pad or decoupled riser for your sub is a good thing!


- Stuart -

[RyanC]

Thanks Stuart-

So just acoustic caulking under the floor plate?

What about a floor plate that goes over an expansion joint where the concrete has heaved up a little bit? If the gap there is bigger than say 1/4" is there anything else to stuff under there or just caulk it up really well?

On that note, any advice on filing an expansion joint in a CMU wall? Stuff it with insulation, backer rod and acoustic caulk? Is there any exterior acoustic caulk? Thanks again-

[Soundman2020]

So just acoustic caulking under the floor plate

Yep!

What about a floor plate that goes over an expansion joint where the concrete has heaved up a little bit?

If it is just a small area, the a hammer and chisel and a few hours of hard work will flatten it out again... If it's a large area, then perhaps also sanding or slightly cutting the bottom surface of the sole plate might help, as long as you don't take off a lot of wood. Also consider backer rod, in addition to the caulk, and do several thinner layers of caulk, instead of one thick layer.

On that note, any advice on filing an expansion joint in a CMU wall? Stuff it with insulation, backer rod and acoustic caulk? Is there any exterior acoustic caulk?

Concrete is porous. If you have a CMY wall that is part of your outer leaf, and is also uneven, and you need to butt something against it, then I'd suggest plastering the entire wall, to even it out and seal it. But why do you need to butt something up against the wall? What is it that needs to sit flat against the wall?

If it turns out that you don't need to do that, then just seal the concrete with a couple of coats of masonry sealant, or a good paint.

Sealing everything is important!


- Stuart -