Since we plan to have the walls sprayed with low density foam, we don't plan to have house wrap. Instead, we plan to use foil-backed rigid foam on the outside OSB, to insulated the studs.

The house will be brick, except under back porch will be cedar siding. Brick ledge is 5.5 inches, and the walls are regular 2 by 4s, that is, 3.5 inches. I have seen windows mounted on 1 x 4s nailed around the rough opening, but in this case since we will have the rigid foam, I don't know if the insulation will go right up to the rough opening and the window flange nailed through the foam into the framing, or if there will be the 1 by 4 to nail it to.

I wondered if it is proper to nail windows to 3/4 or 1" rigid foam, or is this not stable enough?

Also, before I order my Anderson 400 windows I need to know if I need jamb extensions. I plan to look at Marvin Integrity windows before I pull the trigger, but right now Andersen is the best one I've seen.

I'm sure the builder will clear this up for me, but I need to understand whats going on.

I am in North Texas.