If you hire a licensed contractor, not someone who says he is contractor. Or his brother is a contractor. But some one is obligated to come back and fix the job right if it did fails. Not really likely if it is done right.. And if it fails, it is because it was not done right. In that cause show you local building inspector. He will talk to the contractor for you. Or if you prefer, with this knowledge in hand you can talk to the contractor yourself.
First off, do not try to save money. 90 percent of my work comes after either someone tries to save money on material or hires a handyman. He bids the job. Then figures out that the cheaper he can get the job done, the more money he will make. Then when it fails, they call a licensed contractor. Then I explain why it failed. Most home owner actually would do a good job, if they did not try to save money on materials.
If you are really intent on doing the whole job by your self. Well then you will need some good books. Go down to the home depot and look in the magazine section, an buy the Black and Decker do it yourself book on the project that your working on. They have electrical, plumbing, roofing. what ever you want. These books are up to date with the latest code necessary. As Long as there not to old. Laws do change. It use to be every 4 years when they were using the ubc. uniform building code. Now we switched in California. Now were using the internation building code.
Just remember " When the job is down right, it will never fail. " That also goes with the maintance.If you keep paint on a house painted it will never start to fall off. I have seen houses 60 years an looked perfect. When ask how the house looked so good. ( We just always keep up on the maintained.