I did my renovation recently, removed the metal grill from the half brick wall half grill fence at the back, and erect wall and do glass roof to extend the back kitchen. I submitted application to MPAJ and since the work involve extension of existing building, need architect drawing and signature as part of the submission document. Also need consent letter from yiu immediate neighbours (left, right and directly at the back) within 10 meters (i think)....

I would belive MPSJ would require more or less the same. I didnt do all these myself, engaged a "runner" to manage architect and MPAJ while i sent all the submissions documents that i have.

Your case of erecting full wall - not sure if this constitutes an extension of existing building structure.

Depending on the type of work, MPAJ requires submission of the contractor's CIDB cert.