Hi Casey, Good point on the underlayment removal. Thank you for sharing that. Possible furture underlayment removal is a serious concern. Will you be installing new underlayment before the solid oak flooring is installed, or installing the oak flooring directly to the subflooring? Did your old underlayment, not your subfloor, ever squeak or move on you? A major reason for installing our 3/4" thick underlayment is to prevent the 2" long flooring cleats from penetrating the vapor barrier. So we were looking at the underlayment as an extension of the subfloor. The only reason for the glue is to prevent future squeaks, especially in the field where we can't screw into the floor joists and need to use screws no longer than 1-1/4" so they do not penetrate the vapor barrier under the OSB. If you nstall you roak right to the subfloor you will probably be fine but if you are going touse underlayment again, how will you prevent it from moving or squeaking after the flooring is installed? This is our dilemma.

Gregmills, thank you for replying to my post. In 2009, I had several installers take moisture readings and my floor was dry. BUT since 2009, I had the water damage from the water heater on 3-20-13 which damaged the 5" wide BR-111 Brazilian Cherry engineered wood floors which have not been removed and are over the Floor Muffler Ultra pad that they were floated on. I had to buy area rugs as the planks had cracked and lifted. I was waiting to have the insurance claim settled first before removing the floors. My little 6 lb Maltese got her foot caught costing me over $300 with the vet bill, X-rays and pain medicine. Thankfully nothing was broken when she was running and got her foot caught in the floor and was whimpering and carrying on. That is why I bought the inexpensive temporary small area rugs to cover many of the damaged areas until the insurance company settled with me. I had chosen to install the same Brazilian Cherry Wood but now sold directly by Triangulo to stores rather than first sold to BR-111. I just want to change my width to 3.25" from 5". I would prefer a floating floor again as it felt like a solid wood floor but was not so hard on my feet. The store had bought a large lot of 3" Solid Indusparquet Brazilian Cherry Hardwood so can give me a very good price on installing the solid wood by gluing it down using SIKA 2. I did look this product up and they are saying 3/4" solid hardwood can be glued directly to the concrete since it has a moisture barrier and good holding power but flexible. I did call the manufacture of this wood today and Indusparquet will not warranty the solid wood unless it is nailed to plywood floors. I have get to go to the store to discuss the estimate he prepared for me but I am feeling I need to tell him that I really prefer the 3.25" engineered wood downstairs and upstairs. In the summer time, the air conditioner keeps the humidity level down and the house is maintained at 36 - 40% humidity. In the winter time, the dry air is a problem with my forced hot air heat. I used humidifiers downstairs in the day time in my home office and upstairs at night. I have never had a problem with the 5" engineered wood floors until the water damage so I feel I am OK with the engineered wood floors. But when I go upstairs at night, it is very dry and I have to run the humidifiers on a long time to make my bedroom humid enough so I do not get nose bleeds. This is what I am afraid of with the solid wood. I am also afraid of the install failing downstairs where the concrete floor is not flat/level. I filled the large cracks I found when the carpet was removed in 2009 before the installer arrived to install the floor. I will not use him again as he told me to use 2 less boxes so I changed my order and we ran out of wood and he never came back to finish the job when the wood arrived. I want someone to do the full job and charge me extra for moving the heavy cabinets. I have bought so many stackable crates since I will empty them. I have called moving companies to get prices and in case a store does not want to move the cabinets into my garage themselves and to put them back on the floors.

Cork, as I mentioned in the earlier thread, does not need to be glued. It can be floated. That means it just sits there. Doing nothing. Minding it's own business. An engineered hardwood that is DESIGNED to be floated (must state on the installation instructions) can then be floated over top. The tongue/groove is glued (a line of glue is applied to the tongue/groove) and then pushed together. You wipe up any excess glue and then move on to the next plank. Some blue tape is then used to hold the planks together while the glue cures. It takes about a day. Once you the glue is cured, you have a fully functional floating engineered hardwood floor. Done. It is MUCH CHEAPER and much faster (almost half) than adding new sheathing and then gluing/stapling the hardwood. Whether or not you can float/staple will be clearly notated on the installation instructions.

So here' the deal. I've investigated sound transfer because I used to sell cork flooring and underlayment products. Here's what I know: 3/4" wood = 5 dB of noise reduction Regular "pink" R19 insulation = 5-10 dB of insulation (IIC and STC) 6mm of cork (1/4") = 11 dB of impact and airborne (Delta IIC rating) noise reduction 12mm of cork (1/2") = 22 dB of noise reduction (Delta IIC rating) Consider: a human conversation at 3 ft apart = 60 dB. Your set-up so far = 5 dB + 5 dB + 10 dB = 20 dB of reduction Your set-up is considered 'normal' for a family home. Nothing more..nothing less. If you intend to glue down the hardwood, I would recommend 6mm or 12mm cork for underlayment. The cork can be glued directly to the substrated (plywood) and then the wood floor can be glued to the cork. This is called a double stick. If you are planning on nailing down, you can sandwich the cork between the 2 layers of subfloor. Do NOT pierce the cork with metal. Metal conducts noise (aka...phone lines used to be made of metal) over distance. If the entertainment room is in the basement, this is easier. You only have to work with 5 of the 6 sides of the cube. If the entertainment room will be sitting ON the hardwood (as in the theatre room is UPSTAIRS) then this just got more difficult. Now you have to mitigate all 6 sides of the cube to reduce noise transfer from one area to another. And remember: the low-frequency sound emitted by theatre sound systems can be a BEAST to deal with. This is different from regular airborne transmission. Theatre noise usually incorporates HUGE amounts of volume throughout the entire human acoustic range 20Hz - 20,000Hz. Regular human vocal sounds (airborne sound) sits in the 300 - 800Hz range. This is what most "regular" insulation deals with. Green Glue, Mass Loaded Vinyl, Rubber and cork all deal with the 500 - 2,000Hz range quite nicely. The problem comes in with the lower stuff (20-300Hz) that you FEEL in your chest but don't recognise as "hearing" it. These deep vibration noises are often used in the movie industry to bring about the unnerving sensation of "tension" or "being watched" or any other form of sensation common with thrillers, suspense or horror movies. The UPPER range (the extreme range of violins, piccolos, cymbals like high-hats, etc) are also a problem. Not many products on the market can deal with high pitched noises (4,000Hz = most annoying noise to the human ear = finger nails on a chalk board = highest note in the piccolo's range). These "bothersome" sounds are rarely found in the day to day running of a household. Talking on the phone, cooking a meal, typing on a keyboard, walking down the stairs are all noises that are either intermittent (foot steps) or of such low volume (not very loud) that normal insulation practices are considered adequate. The problems are magnified when these problem noises are PROLONGED or of such VOLUME that they overwhelm the acoustic system....as would be the norm for a home theatre or home entertainment system. In otherwords it is SOOOO much cheaper to assume your theatre room is GOING TO BE A NUISANCE and mitigate it to the point of financial hardship. Do everything you can think of to keep the room as isolated as possible. How much irritation are you and your family willing to put up with? If your love of a theatre system out-weighs your irritation, then you are just fine. If you WANT more insulation and you EXPECT more noise control, your set-up won't do a thing towards what you want or expect.