I am not sure if the self leveling line item refers to the bathroom floors which are going to be tiled.

I have a call scheduled with my designer to clarify the various items but I wanted to get a sense of what whether certain things were completely out of line before we spoke.

As President Reagan famously said - "Trust, but verify" :-)

Does the $8 per foot only include the wood floor labor installation, or the labor for installing the cork and plywood as well?

It includes all labor of plywood, cork as well as supplying the materials for the cork and the plywood - everything except the actual wood which I will be supplying.

As long as I am on this thread, is the plywood necessary to install wood on a concrete floor? There are no moisture issues as I am on the 10th floor of my high rise.

What functionality does the plywood - then cork - then wood top layer serve?

I am replacing old wood floors that I installed originally when I moved in and they were glued directly to the concrete as far as I can tell. They were 3" oak and finished on site with just a clear stain so they are not super light but weren't stained - kind of light amber. They lasted very well for many years.

The cork is necessary for code of course now but I am not understanding why the plywood layer as well.

The $8 per square foot is just for installation of the wood and I assume the cork and the plywood. There are the additional costs for the cork, plywood and glue (i.e. materials for the under layers).

I am not clear whether the self level flooring line item is for the wood portion of my unit or the bathroom floors although my two bathrooms are pretty small :-) and that seems like a lot of bags :-)

I'm going to ask about the plywood as I really don't understand why the cork can't be glued to the concrete slab and why the plywood is necessary.

I am waiting for a call from my designer and this is one of the several questions I have :-)

ETA - The flooring installation is one part of the contractor's bid. He is also demoing and taking out the existing wood flooring.

Is this the only quote you got?

I'm curious as to why there is a need for all the self-leveling plus a layer of plywood.

The most important part of a floor is the preparation. I believe the SLC will be poured over the cement to level it. Then the plywood (luan, I believe), then the cork, and finally the finished floor.

Go to the mfgr web site for the flooring you purchased. It will have specific installation instructions.

It's not just the high cost of labor - everything has to be hauled up to the 10th floor.

Thanks Geoffrey - what is luan?

Yes everything is way more expensive because of the logistics including shorter work hours mandated by my HOA so people aren't disturbed at the crack of dawn :-)

I've learned enough from this thread to now have an intelligent conversation.

So the SLC and the plywood are both necessary for adequate prepping?

Luan is crap. I can’t imagine why anyone would be putting that down under a wood floor. And I don’t see why you need any wood under that floor.

Thanks for all your input.

I spoke to my designer and she explained that the plywood layer is necessary for acoustic Code purposes in Los Angeles.

The sequence of layers will be:

Self Leveling

Cork Glued To Self Leveling

Plywood Glued To Cork Layer

Wood Glued or Nailed to Cork Layer

Is glue or nails preferable when installing engineered wood or is there no difference?

The plywood over the cork is needed for a NAIL DOWN hardwood. Nail down is the CHEAPEST method for installing any form of hardwood. Glue down hardwood is the most expensive. It is also the BEST for sound.

So....the sound deadening for the area REQUIRES the plywood. You can't get around that. The cork is required so you can't get around that.

You cannot nail INTO cork. You must glue to cork. That is the only option. So... you are adding the plywood for the sound requirements AND for the installation options.

With all those layers, the labour costs are bang on. If you estimate $2/sf for EACH LAYER of prep....you come up with $8/sf without MUCH EFFORT.

The glue for the cork to concrete = only option. The glue for the PLYWOOD onto the cork = only option. We call this a double stick. If you glue the hardwood to the plywood you would have a TRIPLE stick. This is the MOST IMPRESSIVE option out there. It is also the MOST expensive option.

You can nail into the plywood = no problem SO LONG AS the plywood is THICKER than the nail shanks. You do NOT want nails reaching into the cork layer.

If the cork layer is pierced by nails, you start to LOSE the acoustic properties of the installation. If you think of each nail as a small telephone wire (ahem...metal TRANSMITS NOISE REALLY WELL) that is transmitting noise from your space to someone else's...and vice verse, you get the idea. One nail is no big deal. A floor with 10,000 nails = 10,000 telephone wires transmitting noise THROUGH the cork insulation and into your space. This is a HUGE deal.

Again, the nail down install into the plywood is NOT an issue so long as the nail shank does NOT reach the cork. That means you want a plywood layer that is roughly 1/2". And with cork costs that are MORE EXPENSIVE than the plywood, you must be purchasing 1/2" cork. The cost of 1/4" cork should be the SAME as 1/2" plywood.

Check your thicknesses so that you can feel confident that the right thicknesses are being used for the type of install that is about to occur. Most of LA likes to see 1/2" cork.

I hope this helps.

Thanks SJ. I feel really informed now. As I stated in my original post, my designer is very up on what is necessary for high rise residential condos in Los Angeles but I like to feel that I am making as informed a decision as possible - no different than researching medical issues but then ultimately relying on a trusted doctor :-)

If I understand correctly, your recommendation would be for glue to the plywood because it adds to the acoustic protection and also prevents any potential issues of piercing the cork.

And, there is no functional benefit to the actual wood in terms of one looking or "acting" better - acoustic issues aside - if I understand correctly.

I don't recommend glue down engineered over your set up over nail in place. Either one is a great option. The caveat being: do not let the nails pierce the cork.

The question of how stable a glue-on-glue-on-glue would be my only question. I've never "met" a TRIPLE stick. I have met several double sticks and they are amazing finishes. I'm not very sure how stable a glue+glue+glue would be.

I would be happy to see the cork glued to the concrete (normal) and then the plywood glued to the cork (normal) and then the engineered hardwood NAILED to the plywood. I have no problem with this format.

The 3/8" wood floors rank as a "zero" acoustically. They are thin wood which is traditionally ignored by acoustic experts. There won't be much difference from the raw plywood vs. the finished wood sitting on top of the plywood. It *might add 1-2 dB. And to the human ear, that isn't a very big amount. We start getting excited around the 5 dB range. And 1/2" plywood is worth roughly 5 dB. The 1/2" cork is worth 22 dB!!! That's where all the "work" is coming from.

What is minimum IIC required in the building? You should be able to glue cork and glue flooring onto cork with a glue that has noise reduction on both layer. If, minimum IIC is 55, that will exceed minimum requirements.

If, you install plywood, you need to pad the perimeters also. I would float two layers of 1/2 plywood and use 3/4" thick flooring.

FILC rating of not less than 55 decibels per our CCR’S