1) Do soil test to determine the density of the land.

2) Once complete the soil test report, give to the structural engineer to design the trusses / roofing
inclusive the proposal of the based foundation.
(do you required cat walk system for the roofing maintenance -must mention to engineer) and type of roof selection.. got several type of
metal deck roofing system.

3) Design and calculation must endorse by the engineer. (MUST endorse ya)

4)  Get a proper Q.S to quote the quantity... if too expensive the fee... give to reliable contractor. must follow
structure design specifications and steel size. (quotation must specify the steel size ) don't find a contractor all put Lump sum

5) Once you got all that figure out - overall budget from the contractor-  go to Majlis Perbandaran Kangar to do proper submission.. or whatever majlis related to your area.....

6) you need proper building plan approval and bomba approval (active and passive design) for factory in order for you to operate the factory...even your operating license -business premise license required this....
Hope this help
cheers mate
Izwan
www.archidstudio.com