Without knowing what code you are working to, what your customer's requirements state, what material you are working with, or what form of NDT you will be performing, there is no way anyone can give you a useful response.
It appears you are needing to know if your customer's reference to material thickness is just the for base metal, or if it would include the thickness of the base metal + the thickness of the weld metal.
In my experience, most references to NDT and material thickness would only be for the base metal, you would not add on the thickness of the weld metal. Again, without more information this is probably not very helpful.
Comments thus far are spot on.
IMNSHO, usually when UT is called on for PJP's, they are wanting to check to assure weld size has been achieved and that the depth of bevel, process and parameters, and operator technique have indeed succeeded in producing a weld with the desired strength.
Also, the weld can be checked for soundness during this but it takes great care. As D1.1 does not specify UT for PJP's nor provide any accept/reject criteria for such, agreement must be reached prior to provide documentation and criteria that all are comfortable with. Job specs will need to specify what the criteria will be.
Have a Great Day, Brent