10x10 Grow Room

Well, you have gotten some interesting answers. A lot of good input. If I were you, and was planning this room I would start a little LARGER, particularly if its in a three car garage. Besides the room you are growing in your going to need room to work. I would suggest you check out AL B Fucts post 'How to grow a harvest every two weeks'. 4-4' by 4' tables and a cloning/mother area, 13 to 16 oz every two weeks.
I would start with then planning basics. Suppling electrical outlets, plumbing, drains, Ventilation. A little extra now can save you a ton of work. Plan it so controls are easy to get to. I would consider a reverse osmosis set up for that size of room as well. Use 20 amp breaker for each circuit that will be handling an hid light and minimum 12-3 cooper wire. A water line into the grow area as well as a drain out of the grow area will save your back. I'm going to set mine up using airline and fittings made for an air pump so I can change my reseviors, oops you said your using soil. Set up ventilation so any air exhausted to the outside is comming out the roof etc. then start on the actual area within the room that you are going to grow in. Be the electrician, plumber, hvac man you always wanted to be. And when you build the walls, if you put styrofoam over the outside of the studs it will give you better insultion and deaden any sound at the same time. This will also stop light leaks. VV

Well actually scorpio will have 2 5x10 rooms if he splits it in half. I think you should have a larger flower room than veg, maybe 2/3 of the space or more for flowering depending on how long you veg and how many plants you go with.