You should hire a clerk-of-works ("kerani" local speak) to help you sort out all your questions. They'll help you with specifications for everything, how to do things, and check that things are done properly and using the correct materials onsite. Good investment if you are doing major renovations as the additional cost is not that high. If you are in the Klang Valley I have the contact of someone experienced if you are interested.
PM me for the contact . I know him from my kampung. Charges were reasonable for the work