[sxn77]

I'm trying to install a floating wood floor in my condo:

The HOA rules state: "For wood floors adequete sound proofing must be installed". A minimum of 3/8" plywood or cork underlayment must be used with a minimum of 1/8" mastic on either side of the plywood."

The idiots at the property management firm don't know how to interpret this language and keep giving me the run around and changing requirements. I talked to home depot and my contractor. They said I should install a 1/2" plywood sub-floor and on top of this lay 1/4" of cork sound proofing. On top of the cork i lay my floating wood floor (about 1" thick). They said this should exceed the requirements. Is that correct? Any advice or knowledge of the best and most cost effective way to meet this requirement?

 

[Floorwizard]

Sounds to me like the Cork underlay should be enough.
Not sure if additional ply would help, but I admit I am not sure.

 

[gma2rjc]

Since they keep changing the requirements, get it in writing as to what they want. Take pictures of each layer of flooring that is put down. Ask the installers to include the details of the materials used on your bill. Keep it all in a file. Some day you may have to prove that you did use the required materials.

I'm assuming the floor needs "adequate sound proofing" because you have neighbors living beneath you? The materials they want you to use will help deaden the sound some, but not very much.

They should have thought about sound proofing when the condo's were being built. I could be wrong, but from what I've read, sound proofing materials need to go between the floors to be effective.

 

[sxn77]

thanks for the feedback.

I do live in a high rise condo and have people living below me. The floors, ceilings and even the side walls are made of concrete. According to building maintenance there is at least 1-2 feet of concrete between floors, so I'm not even sure what the big deal is when it comes to sound proofing. Apparently the engineer who approved flooring requests retired in April so no one on their staff knows how to interpret the HOA rules on flooring. I had to escalate to the vice president of the management company and they gave me the OK

I am definately documenting everything they said was OK, as well as all the specs. Apparently they need to come and inspect the floor halfway through the project.

 

[sowatson]

Some ideas.....

Yes, the plywood would add additional soundproofing capabilities but the amount will be negligable. The Cork material would be a better choice if it were offered in 3/8" thickness. The problem with this of course is that no one seems to understand and that is something that can be a real problem. Additionally, lets say you used cork and then plywood and then mastic (interesting - Mastic is a lot of things, but it was always roof cement to me).
Ultimately you have to comply with the HOA so you are at their mercy. I was developing a panel that had laminated foam face and back to a plywood core for just this sort of an application. Trouble was that there was no way to identify a specific building code in New York or California that was intended to limit this sort of noise. What entriges me is that as was stated before, with this much concrete how much sound problem is there? It seems to me that all of this is something that was engineered in someones mind and therefore it has crept into the building code throughout the nation. I hope this helps in some small fashion.

 

[sxn77]

Thanks for all the info, it is helpful.

The only cork soundproofing I could find is 1/4" at the major stores like Loews, menards and home depot. There is premium sound proofing material at 1/8" made out of vinyl or fiber, but 1000 square feet is really expensive. No way I could afford to buy that and place it over and under the plywood subfloor.

I think the person who wrote up the HOA rules mixed up the requirements for hardwood floors and tile. I could see mastic being used underneath tile, but it doesn't make sense how it would reduce noise over and under plywood when I am getting a floating floor.

 

[sowatson]

Mastic.....

This is interesting. I actually went back and looked up what Mastic was. In its purest definition it is actually a sap from a tree in Greece that they make a gum out of.

But in modern construction Mastic is described as a flexible adhesive membrane that does not harden over time. In my experience roofing mastic of course does harden but the concept of a flexible material like plumbers putty to make a seal in a sink makes perfect sense. I think that the HOA was trying to get the sub-floor - plywood or even better cork - glued down and then the floor being glued on top of that and in both instances the semi-flexible mastic would provide some give in the floor and interrupt the sound transmission qualities by not having a rigid membrane.

FYI

 

[sxn77]

This is interesting. I actually went back and looked up what Mastic was. In its purest definition it is actually a sap from a tree in Greece that they make a gum out of.

But in modern construction Mastic is described as a flexible adhesive membrane that does not harden over time. In my experience roofing mastic of course does harden but the concept of a flexible material like plumbers putty to make a seal in a sink makes perfect sense. I think that the HOA was trying to get the sub-floor - plywood or even better cork - glued down and then the floor being glued on top of that and in both instances the semi-flexible mastic would provide some give in the floor and interrupt the sound transmission qualities by not having a rigid membrane.

FYI

If that's the case, I think a product like this would work as the "mastic":

http://www.greengluecompany.com/

But I can't see this type of glue being 1/8 inch thick.

 

[sowatson]

You are correct....

You are right. Any sort of material delivered in this fashion is not going to be 1/8" thick. This does look like an good material - very interesting. It could of course be applied with a notched trowel of 1/8" thickness but the ridges would be compressed when the other plywood were placed over it. The point being that the required code as written is out of date and needs to be rewritten to explain the intent better.With engineered floors one does not necessarily have to nail or glue the floor down which is what I prefer. However, these two customers in New York and California both said the HOA rules required then to glue the solid wood flooring down the the underlayment. I don't know why they would require that - ergo the reason i was working on engineering a plywood panel with a foam sound deadener layer top and bottom over the plywood.

Anyway it seems like what you decided on should work fine and if they approved it then you are off the hook in my opinion.

Good luck, let me know how it turns out.