The electrical has to be certified by an electrician. The framing and plumbing, you can do it as an upgrade to your home. There's a grey area about permits for the home. On the weekends do most of your work, and make sure your neighbors know you're doing this. The noise tends to aggravate people. The plumbing, if you're tieing the new pipes into the existing line, you don't need a permit. If you're digging up your yard to get to the water or sewage lines, you need a permit. I am assuming that you are doing this yourself. If you have a contractor, they know what needs a permit. If you're digging out a basement, yes, you will need a building permit. The forms for the walls, the cement, etc. I hope I helped you. Good luck with the remodeling.
It depends on where you live. You need to contact your city manager to find out.
Yes, you need permits for all three trades as well as mechanical if you are running ducts for heating/AC. I'm not sure of the cost, but I know it is much cheaper for an owner/builder than for professional contractors.
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