garage addition

Check out the link below. It's got good info re: the questions you ask.
Good luck and take the time to think things through.

Roger

• PLANS

You should bolt the header to the garage wall with 3/8's all thread. Nails are not enough. You can toenail the 2x8 rafters right to the header. Use 6 nails per rafter to the header. 2x6 rafters are fine for a 10 foot span on 16 inch. I just put my first rafter up along the side and marked it. This I used for my template. If your garage wall is crooked, your rafters will need to be a different length as you go along. 6x6 posts will work perfect. I would put these 8 feet apart, and run TWO 2x8 beams nailed together so the rafters will sit on them.

You will need a slope at least between 3-12 pitch and 4-12 pitch. My addition uses 2x6s 16" on center. After putting shingles on 1/2 inch plywood, I have a pretty solid roof. I put my roof pitch about 3.5-12, so that prompted me to put the shingles on 4-1/2 inches spacing.

Finally, you will need to do some extensive flashing and tarring along the crest of the roof where it meets the garage. Additionally, use 4x4's or whatever you have to brace the 2x8 beams to the 6x6 posts.