I'm pretty excited about my new room i'm building

It would be pretty shabby construction if the screwed in dry wall were pushed away from the studs by too much insolation. If I were to do a room from scratch, 2x6, I would shoot liquid foam insolation into my walls and fill every nook and cranny! They even have different liquid foam for a variety of applications. Sound proof and the likes. I used it for panels for my walk-in cooler. When I do my frontal lobotomy's you can't even hear the screams!

He used 2x6, so if you use typical 4" fiberglass bats, its not going to fill the void. If he used a r36 insolation for 2x6 framing, that would be a much better application. I know of applications where the foam (which hardens) would fill any voids with the fiberglass insolation. I would think the denser the internal wall the better the acoustics? I live in a log home 6" thick and the solidity of the wood makes for very good acoustics.

I used that acid stain in a 24x24x17H building where I make wine. Results vary with what you want to achieve. Your going to want to seal it. I assume a moisture barrier is under the slab? Your basically etching the concrete with the acid. You can get some really cool results. I don't think you will be walking around in your bare feet. As far as insulation, have you priced foam, where it is sprayed into the walls? Acoustically I would think that would be better than fiberglass. 

Open cell foam spray with styrofoam sheeting...

Thank You for the construction tip George. I would have never thought that it was the head of the screw coming through the drywall! Forgive my wording! George you are wrapped far too tight! 

If the concrete is finished with a gas powered trowel, you can get it so slick and it develops a black hue to it. It actually burns the concrete. I'm in NC to, anything outdoors sealed is difficult. Indoors with what oleschool wants to do with the acid finish, sealing will enhance the colors. I've seen some pretty cool epoxy finishes.

Oleschool, I did look at the acid product your going to use. When it comes out right you can obtain some very cool results. First time I saw it was in a bar and it really looked cool. You want to have variances in the colors to give it that patina look. I chose a rust color and it did not come exactly as I wanted. A lot depends on the porousness and finish of the slab. If memory serves me, length of time with the product on the surface helps in obtaining that patina look I was mentioning. I also think muriatic acid can be used within the application? I also used a stiff brush to work the product in attempt to get that off set in color. It has to be sealed after completing. That really brings the floor to life. Because its not a commercial building a good sealer should last you a while. I used a water based sealer, I'm sure they must have oil base as well? With Cali. that's likely an issue?
Several epoxy products out there. Its a 2 part application, and don't know if its a first time DIY project? Once its down it's easy to maintain. I've seen it dusted with flakes to give it texture and a certain look. However its a solid not transparent look.
I'm jealous of your of the grid power approach. I'm on 40 acres surrounded by 300. I use a water stove. Essentially a boiler, with pipes underground that pump through a heat exchanger. Its about 100' from the house. Heats the house and hot water. I use it year round. Lots of cutting and splitting  of wood. Emerald ash borer are killing all the ash trees so that's what I've been harvesting here in NC. It migrated down from Canada. If I were to do it again I would take your approach. I have a stream behind the house and I get sun all day. Too far along in the game now for me, but I tip my hat to you with your off the grid living! I Couldn't imagine living any other way. Good luck...

Just curious Ray, what do you do for internet? I have satellite. That's my only option, so deep in the woods cell phone is not very good. I have to keep a land line, AT&T won't run fiber. John

Ray, I'm also on Viasat and DTV. Viasat oversell their systems capacity. Been with them since Wild blue days! Only options Hughsnet or Viasat. What kind of downloads speeds can you get? That has been an adventure of its own! The price we pay for seclusion.

That's pretty ironic Ray, not everyone has a sauna. Both you and I do! First project after building my log home was a 8'x12' sauna on the back deck. Been using it almost everyday for over 20 years. On my 2nd heater, Swedish made Tylo. BTW, for a speed test on Viasat, just search speedtest.net and hit go. It will tell you your download, ping, and upload. use Ookla, just hit go and it will give you the numbers. Take care..

Mine is  Western Red Cedar. Trouble with Eastern Cedar the knots seep sap and it will burn you. I have 2 benches, I should have built 3. Wow 12 people! I'm trying to think if I even know 12 people! LOL!  I do 20 min a day, and sometimes go back in after a cold plunge. I was going to go 8'' log walls for the house but it was a lot more money. I have square logs 6" thick. Health benefits of sauna are off the charts. Let me know your download speed with Viasat. Take care...