Decks, Patios, Porches and Docks - Vapor barrier under carpet ?

Hello,

I might have posted this question at an earlier time. Our back porch was enclosed in all glass, sliding doors, etc.. I am going to finish the inside myself. My question is concerning the vapor barrier under the carpet.
This will be a three season room with heat from a couple of portable heaters. The floor surface is 50 year old concrete. I want to use some padding with an outdoor carpet. "Vapor Barrier" is my question. Can I use plastic right next to the conctete or just use a padding with a vapor barrier? Does it make any difference?

Thanks so much!

An indoor/outdoor carpet is plastic -- it is it's own vapor barrier. A foam pad is foam -- moisture won't affect it, unless you remove it's ability to 'breathe'.

Lay the pad, lay the carpet -- forget the plastic.

Indoor/Outdoor is plastic, but it's not solid, so it doesn't stop vapor or liquids.

Lay the plastic, but not your normal plastic sheeting, you need a good thick vinyl to hold up to the mix of abrasive concrete and people walking on it.
Not only will you keep out the moisture from the concrete, if you ever spill anything, it won't soak into the concrete, making it nearly impossibly to get out. With the plastic, only the carpet and pad with absorb it, which you can shampoo/vacuum out.

You'll also need a thin (1/4") pad, too much flex on the indoor/outdoor and you will be replacing it every year.

Or, you might consider a vapor paint (like for painting basement walls) such as DryLock.