Without paper work, they give summon, prepare to pay RM 300 to 500 per summon, if they come 3x a week you do the math. Also if your neighbor complain they will come more frequent, and depend the type of complain they will ask you to tear it down or maybe tear it down for you.

For any major renovation, you need to get architect drawing and runner fees, depend on your requirement/design the fees can be around 3k to 10k. The architect that know your area will know what can be done or not to be done.

I think PJ, and KL are much easier to do, cause i see some house in Bangsar turn from single to double, and PJ like Section 17. Look legal to me cause during renovation they put in the notice board (with Architect is XXXX, developer is XYX... information)

I am doing my house in USJ, MPSJ is very strict. For MPSJ, double story, the top floor rear you can't build all the way out, you need to have minimal 5 feet space. Front car porch can't use concrete slab. My architect do all the things for me, after submission and some changes request from MPSJ i finally got my permit after 1 month. According to my Architect, you can change bit of what the submit drawing from actual, but if its too much they still can ask you to demolish it and rebuild according to the design submitted.

nearly 1 month for me to get approval from MPSJ.

If you build 3 stories without approval any of your neighbor complain you got to demolish or the authority will do it for you. Very risky.