Project: Installing a 3/4" solid hardwood on plywood subfloor of 2nd floor house.
Our concern are the noise when upstairs. I was suggested the product floor muffler.
www.flooringunderlayments.com/floormuffler.html
I talked to the manufacturer. They said the product will work. They said the same material is also used in Lexus, Mercedes as sound proofing.
However, our installer said that the noise will just be transmitted thru the nail/staples. But most probably, it is an added work for them installing it that is why they hesitate.

Is this a good option for underlayment for sound reduction?

I concur somewhat with your installers. In all the tests performed with the floor muffler, the floors were either floated or glued; none were nailed. You may get some sound/noise reduction but not as much as if you glued a floor down to it. From an installation perspective, it isn't difficult to install. Really, no more than #15 asphalt felt paper that is typically used under solid, nailed down floors. If you were my customer, I would install it as recommended but would NOT warranty any benefit to you. IMO, it probably won't hurt but may not help much either. Sound and noise control is a much more complex problem than a simple pad on a floor can deal with.

[quote="Gary"]I concur somewhat with your installers. In all the tests performed with the floor muffler, the floors were either floated or glued; none were nailed. You may get some sound/noise reduction but not as much as if you glued a floor down to it. From an installation perspective, it isn't difficult to install. Really, no more than #15 asphalt felt paper that is typically used under solid, nailed down floors. If you were my customer, I would install it as recommended but would NOT warranty any benefit to you. IMO, it probably won't hurt but may not help much either. Sound and noise control is a much more complex problem than a simple pad on a floor can deal with.[/quote]

Thank you Gary for your response. In your expert opinion, what will be the best option for sound proofing a 3/4" solid hardwood on plywood subfloor of 2nd story house?

Would it be cork, rubber, foam?
What will be your recommendation

IMO, it doesn't truly exist. Insulation between the floor joist will help, as would cork underlayment, but none will eliminate the sound transferring to below. To do that, one needs to completely de-couple the upstairs subfloor from the framing. So , with that in mind, a solid 3/4" floor nailed to a floating subfloor over a sound reduction pad would achieve the best results for sound reduction (not sound PROOF). Alternatively, a solid or engineered floor floated over a noise reduction pad would also transmit less sound to downstairs.

Floating option makes sense Gary.

For the sound reduction pad with a floating solid hardwood flooring.
1. Are you referring to floor muffler as a best option on this scenario over cork?

2. I understand that in lab tests, floor muffler is the highest rating, but does it really do exactly as they say in real world?

3. What adhesive is the best?

4. Will adhesive hold the hardwood to the subfloor as long as a nailed down or stapled?

5. Would a glued down 3/4" X 5" hardwood over floor muffler seems to move on the planks edges as you walk in it?

6. How long before it is needed to reapply adhesive?

7. When you mention insulation between the joist, what kind of insulation is used?

1) The test data seems to show the Floor Muffler is better at noise reduction under a floating floor than other types of pad underlayments.
2) I don't know!
3) Adhesive for what? This is a floating installation!
4) I thought we were discussing floating the hardwood.
5) You would need to discuss that with the manufacturer. If I were to ATTACH a wood floor (not float), I would probably use the tried and true method of gluing cork down, then gluing the wood down to the cork. I wouldn't glue a solid wood floor down only. For glue down only, I would use an engineered designed to be glued down.
6) ?????????????????????
7) Typically, fiberglass batts.

I got mixed up about glued down and floating. Now I seem to understand. Its our first time to wood flooring so terminology is a bit novice.

One concern about floating versus nailed down is that I heard that nailing it down to subfloor through the joist gives strength the the house "framework"

I first thought that it is the opposite because you added extra solid hardwood weight so there is more load stress on the house.
On the other hand, by nailing it down thru the joist will make flooring more "sturdy"

What is the truth about this?

When a solid, 3/4" T&G wood floor is installed over a panel or plank subfloor, it will add rigidity to the floor (stiffen it). It does nothing for the walls or roof. When nailing over 3/4" subflooring, the fastener location is irrelevant as it isn't long enough to penetrate very much into the floor joists. But when using 5/8" subflooring, some of the flooring fastener will "tag" a joist. However, do not make the mistake many do. And that is thinking that they need to nail into every joist location. IF your subfloor is of good quality and well attached, it does not matter if your nail into a joist location or not. THE EXCEPTION is when needing to face nail the flooring. Since one is nailing straight down when face nailing, much more hold can be obtained by nailing into the joists as a typical 2" finish nail will get about 5/8" into it.

There is a parallel discussion on this site...
http://carpetfitters.biz/flooring-forum ... #entry7271
[url]

What is your opinion on using sika acoubond adhesive system?
Do we have this here in the US?

What is your opinion on "float a 2 layer plywood subfloor over a sound absorbing underlay and nail your solid wood to the floating plywood subfloor."?[/url]

It is available here through flooring distributors. It is a relatively newer system so no long term data exists. It appears impressive but I'm not sure the main function is noise reduction.

It is a tried and true system. One of our posters did this in his home over a year ago and was very happy with it. It went over a concrete slab, which is inherently pretty quiet. As I mentioned before, de-coupling the wood floor from below is the best way to reduce sound transmission to the floor below. It can be done by floating the subfloor or floating the flooring itself.