Questions about a travertine installation

Hi Bud, I saw your responses, very impressed. I have a question re 18x18 travertine on the concrete slab of a 4 year old home. The slab which previously had carpet is in good condition, clean and quite level. We are in Riverside County of Southern CA which is normally dry weather. Do I need a moisture barrier under the travertine such a gel carried by Home Depot that can be spread on? Also I have "Polymer-Modified Motar" that is white powder and "Patch & Skimcoat" that is medium gray powder. Do I need to use both of these for travertine on concrete slab? Please also send response to my email if possible.
Thanks Bob

[TFP Admin]

Registered members have the option of allowing their fellow members to email them and it still protects them from spam by not showing your email address. The only way to reveal your address is to reply to one of those emails. We strongly discourage all members, and do not allow unregistered visitors to put their email addresses in their posts.

Thank you for your questions. I moved this from the "Discussion: Tile Over Vinyl Flooring, by Bud Cline" topic because it wasn't a discussion about the article (we are very happy you read it though), to a topic of its own where it will do the most good for you and everyone else.

TFP Admin