What is the height for that deck? If you under 30" maybe you can get away with that height...
Tell the Homeowner to go down to the township and get a Code Modification Request form. Have him fill that out and there is a good chance this could fly having the deck height under 30".
Done that quite a few times with great success.
What you basically want to show that the modification you asking for is reasonable and it will still provide equivalent safety
Show that your requests is based on practical difficulty in achieving code conformance on the existing railing and in your case the deck is under 30" and that the existing rail being 1 1/2" short of 36" it will still provide equivalent level of safety and protection.
Explain as clearly and completely as possible the nature of the code violation and the proposed change to the following code and use these codes as reference:
R312.1 Where required. Guards shall be located along
open-sided walking surfaces, including stairs, ramps and landings,
that are located more than 30" measured
vertically to the floor or grade below at any point within 36
inches horizontally to the edge of the open side.
Add R312.2 Height. Required guards at open-sided walking surfaces,
including stairs, porches, balconies or landings, shall be
not less than 36" high measured vertically above the adjacent walking surface.
Include with that a drawing and a few pictures of existing condition and you shouldn't have any issues.
Good luck.
