Hello Stone and Tile Pros,

I am working with a client who has a newly installed (a year ago) travertine patio, retaining wall, bar (large without proper support) and the flooring has pavers (no pitch and very loosly installed).  We were called in by the General Contractor because the installer has scratches all over the entire project.

Many issues...but my question for now is:
 
The General Contractor is arguing saying that there is no need for any kind of weeping system behind the travertine tiles that are installed onto the retaining wall.  The wall goes as high as about 5'.  The tile are all loose, the wrong thinset was used (I saw it when a piece was already off).  The back of the retaining wall was left unfinished without any tiles.  It is just concrete block.  You can put your entire hand through it.
 
Am I wrong with saying it must have a weepeing system unless the manufacturer's installtion instructions indicate otherwise?  Everything I have ever known as far as industry standards require a weeping system.  On my moisture reader, the wall is showing a 13 - 28% in moisture.  This was on a dry day without rain for several days.
 
Not only no weeping system was used and hallow holes behind the wall, but the wall was installed before the the flooring pavers which have no pitch so the water is trapped and going nowhere.  But the General Contractor insists I am wrong.  So I told the homeowner I would check with all you gurus with Stone and Tile Pros and get your exact thoughts to send to her.