Insulation, Radiant and Vapor Barriers - Another crawl space Q

I'm thinking of sealing off and putting down a vapor barrier in my crawl space. Is a vapor barrier necessary or desirable over the parts of the crawl space that are paved or only over the dirt sections?

Thank you

If there is a VB under the concrete then one on top would not be needed. But if there is none under it then yes it is needed because the concrete is no better than the dirt in letting the RH in to your crawl.

concrete is no better than dirt to keep moisture out of the crawl space.

If you are planning to seal off you crawl space, the best thing to do is to completely isolate it from the ground and make it a part of the internal envelope of the house.

You will need a thick crawl space liner (many use 6mil but I'd recommend a sturdier 20mil), covering the floors and running up the walls, fastened with xmas tree or other mechanical fastener (adhesives can never hold it well enough, they get pulled out of the walls as people crawl around), sealed with mastic tape and caulked.

However, be careful if you have any combustion appliances running in the crawl space. They need a consistent air supply.Do not depressurize your crawl space if you have combustion appliances running in.
Although this is a job that a seasoned DIYer may be able to tackle, don't do anything if your are not 100% sure of what you are doing. Call a pro.

Thank you. I'll try not to blow things up.