Sound room flooring advice needed

Bill, Zenblaster is spot, I just did this last year and it sounds great. Best of luck...

Wrm57-
I have been involved with residential construction for 30 years and have built dozens of houses on the CT shoreline in the $1m range.
Is this a below grade basement? Are there any existing water issues in this basement or any drainage issues outside the foundation? water is always the biggest concern in a below grade basement.
If you live in Vegas or Az you won't have to worry about moisture but if you do. We use the 2x2 interlocking subfloor that is rubber like on the bottom and a osb on the top. You can put a floating (engineered)floor over this and your speakers will be solid as if they were on the concrete itself. I would mount turntable to stud walls as a matter of best practices.
I have used this product in the past and it's great.
Dricore

Hi Zenblaster,

Thanks a lot for the helpful response. I'm in the SF bay area (near the bay), so it's typically dry for eight months and rainy for four. The heavily-sloped property has no apparent drainage issues. The space itself is more on-grade than below, with no seepage issues; but some of the original linoleum tiles, installed in the mid-1950s, have popped from efflorescence, so moisture has obviously come through the slab at some point.

The Dricore looks like an excellent product, if a little pricey. Do you need to install a separate vapor barrier, like 6 mil plastic, too? Does the engineered hardwood flooring go right on top of it, or is another float layer needed?

Bill

The good news is that any water issues would have shown up long ago. That said, I would treat the floor as though it was a shower base. They have a waterproofing that comes in a 5 gal buck and you roll it on, as waterproof as a swimming pool when it dries. Make sure your concrete floor is relatively flat and clean. Roll this stuff a few inches up the walls and you are ready to go with the Dricore.
There are several companies that make similar products to Dricore and I would check them also to get the best for what you need.
You can contact me by email if you have any questions that might not pertain to this thread.
Good luck with your project, do it right the first time.

are you talking about a swimming pool? I remember when I built my listening room as a separate building deep into the earth my wife claimed it would have been better if I had decided going for a swimming pool.
Nevertheless when you have the chance to build it up I would go for a good concret basement, some layers of isolation treatment, then a wooden floor of heavy large pieces at least 40 mm thick. On top of that I would work with carpets and isolation treatments again as you are already doing. Don't forget a proper treatment of the walls and the ceiling. This is such crucial. It is not only the floor. The waves have to be vaporated at the side walls and also look for proper reflections of the different frequences coming from the ceiling in front of your listening chair. This is very important for the real good sound you are going for. Good luck, too.