My attic is partially finished, with another section that is not finished at all. I’m planning to finish both attic sections. What steps do I need to put in place to ensure proper ventilation, insulation, etc. in this situation? I will be doing this myself other than windows, electric, and plumbing.
Finishing your attic is a great project because it is an area of the home most people don't take advantage of! So, it makes a lot of sense to utilize it as a living space. Insulating an attic space like that, however, is difficult. Basically, you want as much insulation as you can get.
However, in a finished attic, you don't have a lot of room to work. At the uppermost level of the home, you most likely want to have 15-20 inches of insulation. This is almost impossible to achieve in a finished attic situation. Typically, you're going to be insulating the underside of the roof rafters - and if it's fiberglass insulation, you have to leave an extra couple of inches for fiberglass insulation.
For this reason, I think your best move is to avoid fiberglass insulation and use spray foam insulation instead. Spray foam insulation is much denser and does not need to be ventilated like fiberglass insulation. It's going to be more expensive for the initial installation, but you will find that it provides many benefits. In addition to insulating, it will also seal the entire attic from drafts. Plus, it has the added benefit of being sound proof. This is why I believe it is the best way to go!
Good luck with your project and be sure to send us pictures when you're done!