As far as I know for MBPJ it is a bit of hassle, they want you to submit for planning approval for this kind of reno
1. more than 50% floor area
2. change of facade
3. add floor levels (from 1 storey to 2 storey or 2 to 3) provided the surrounding neighborhood got people done so
4. demolish and rebuild
This KM can be endorsed by architect.
Usually when it involves structural issues, you need to submit PEPC endorsed structure plans for record only.
You may also refer to the "Local Plan" which is being exhibited at the MBPJ planning dept office, try to look for your neighbourhood/section/SS to see what are permitted and what are not.
The "Local Plan" is a set of document to be updated every 5 years empowered under the Town and Country Planning Act.