Would cork flooring underlayment help with vibration dampening in a sub floor?

Question

Related question: HE Front End Washer vibrations on wood floors: any tried-and-true solutions?

In hopes of being able to keep our new front-end HE washer (which we like) I've decided to bite the bullet and reinforce the floor underneath.

The plan:

• add blocking between joists underneath (crawl space access)
• glue+screw subfloor to joists
• glue+screw additional layer of plywood to subfloor to stiffen everything.

Question:

Would adding a layer of cork underlayment between the subfloor and additional layer of plywood be of any benefit (or detriment?)

The theory is that it might add a bit of decoupling between layers to reduce vibration migration into the framing.

Does my theory hold any water?

BTW, we're thinking of putting tile on the floor when finished. Figuring that it may also add another level of 'stiffening' to the floor sandwich (using larger 1x2' tiles)

Answer 1

I don't have any experience to say for sure one way or the other (except that I've not had any notable vibration problems with my front load HE washer on the first floor, which is just sheet vinyl on 3/4" plywood, near the end of the joists). But what I'd think you want is basically the same thing that that you want when you're soundproofing a floor; you don't want vibrations at the top to transmit elsewhere.

When soundproofing, what you really want is a sandwich of plywood, underlayment, plywood. So roughly what you're suggesting. Cork can work well, though rubber underlayments generally perform much better at the same thickness. You lose a lot of the benefit if you screw the top layer to the lower layer, though - you want the layers glued together, without anything hard bridging across the soft layer.