Existing Concrete pad

[desimulacra]

 I am thinking about building a 24x24 garage/storage building. The storage building part is the problem. I have an existing 24x24 concrete pad that was not insulated and I seriously doubt it has a vapor barrier. To store furniture and other storage aspects of this I will need to control the moisture.  Will this pad suffice? Is there a coating I can put on the top?

[Bill Houghton]

We live in cold climate so even with the vapor barrier and 2" of styrofoam under the slab, it sweats certain times of year.  Probably less than if we didn't have it.  Anything I don't want wet (sooner or later) I will put on a piece of plywood or boards. 

[desimulacra]

Thanks Bill
I am in Tennessee so we have water in the air, some call it humidity but when you walk out and feel it it is water in the air lol
I want to store some old furniture and don't want it to ruin. thought of making a raised floor??

[glenn kangiser]

Sanitred makes coatings that will waterproof the floor but I don't know how effective it will be against the moisture you are concerned about.

[Bill Houghton]

Thanks Bill
I am in Tennessee so we have water in the air, some call it humidity but when you walk out and feel it it is water in the air lol
I want to store some old furniture and don't want it to ruin. thought of making a raised floor??

Raised floor AND a dehumidifier.  A dehumidifier may be too expensive of a solution though, purchase price and electcitity to run it constantly.

[Don_P]

For dehumidifying, if you raise the temperature the humidity drops. The sun can do that, think about a solar kiln.

[desimulacra]

Thanks for the input. I am holding off this year on this option but think it will happen. Looked for a solar dehumidification solution but the only one I could find was over 500 us dollars ;( Better off I think with a cheap unit if I can get electricity to the slab from an existing home. If not min. bill of 35 a month would soon pay that.

http://www.solarventi.co.uk/index.pl?art=3

[JRR]

I have no real experience dealing with your problem, but here are my thoughts:

I would welcome having the slab already in place.  I would start by laying a perimeter block wall; perhaps two block high, perhaps leaving openings for doors ...  depends on site and needs... Then install a vapor barrier, perhaps a screed of roofing cement followed by roofing paper and/or continuous film of heavy tarp.  Then a thick bed of clean sand with garden pavers placed atop the sand bed.  This would work for foot traffic only, no vehicles ... but would be fairly cheap and flexible.  If you needed to come back later and make changes, that would be fairly easly to do.

I would lay the building out so there are large/many windows for southern sun gain ... and a good ventilation scheme.

[desimulacra]

JRR I like your thoughts! Sounds like that would work. I was imagining a built up wood floor.