What type of portico?

How is it ur adjoining your roof?

If you use the right brackets you may not require posts.

I think you're going to have some issues with the current location of lights and that shutter on the left side if you try to do all the framing with wood.

You might be better off with a metal canopy that you can slide under your gutters

Looks like you have a deep overhang, so the portico doesn't have to be that deep. I would use brackets. Remove the shutters, since the window are not right for them. Replace the two lights with one in the ceiling of the portico. If you still want posts, I would say about 6 to 8 inches finished width.

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