73 yr old garage floor help

[KiWinUS]

G'Day guy's , I need advive on my 73 year old garage floor. I have a "Rock" garage that was built in 1945 that I am turning into an "Art Studio" for my Daughter, has several issues I need advise on.
The concrete floor is in bad shape it is very rough , has cracks , some quite large , some area's kind of powdery. I don't believe there is any moister barrier under it as if you sit certain thing on it (like a 5 gal can of thinner or something plastic) it draws moisture from floor.
What can I coat of put on this or ? Replacing is not an option at this time.
Also bottom of framework that sits on concrete is mostly all rottem , moisture or termites dont know what. What should I put between new timber & concrete?
Treated timber or not?
Thanks for any & all help!!!
Thanks
Cheers
Tony

 

[Vintage Veloce]

I rebuilt a 90 year old building like this. It's probably not what you want to hear... but we ended up lifting the building up, jack-hammering all the concrete out, pouring a new foundation (6" higher than the original), lowering the building down onto new pressure treated sill plates and replacing all the other rotted lumber.

Pics would help a lot. Is any of the wood in contact with dirt? Do the bottom wood parts get wet from anything (puddles when it rains?)? Is the inside of the building finished (sheet rock, plaster etc), and/or do you intend to finish it?

You can do as little or a much as you want.

That said, if you get dampness under anything that sits on the floor you probably will have a tough time coating it. A raised deck or racedeck tile type thing might be your easiest/cheapest solution.

Replacing the sill plate is a good idea if it is rotten, and those problems often travel up the framing a bit. The question is why it is rotting... meaning, is it getting wet somehow? And how you are going to fix that problem.

 

[MScott]

I used a product called Dricore on a similar concrete floor when remodeling a basement and converting it to living quarters a few years ago. It uses a waffled plastic layer on the bottom of tongue and groove 2' x 2' panels so it acts as a vapour barrier, an insulating layer and a leveler for the floor. The space under the Dricore gives any moisture a chance to evaporate without damaging anything. It can be covered by almost any flooring so it is great for converting to living quarters.
I agree with Vintage Veloce that the sill plate should be replaced if rotten and you should definitely use treated wood.

 

[rjn2649]

When the post got moved my reply got lost so I'll re-reply.
Garage built in 1944, flood 2-3 times a year and sits in water about a day after the flood.
I began replacing my sill plates yesterday, got one side done. They are just about nothing but powder. I used 4x4 treated, braced the wall up and just cut the the stud with a reciprocating saw using a long demolition blade (nail embedded wood) ground out the steel bolts, and slipped the new wood right under. I need to drill and screw the 4x4 down.
I probably should have put a barrier between the treated wood and the floor. This garage was built in 1944, it's older than me w/o pressure treated wood. So I think it will probably outlive me now

Edited to add...at some point in the future I would LIKE to jack this thing up and pour a pad 6-8 inches higher than I have now...yes this is way of getting around set back rules and some code issues....