I thought I would use a 2x4 and use lag screws to screw it to the side of the house. The 3' wide gate will fit between the 4x4 post set in concrete and the 2x4 attached to the house (garage).
Will this arrangement compromise building codes or cause complaints from termite inspectors when I sell the house? Of course, the 4x4 is treated lumber. Do I need to use treated lumber for the 2x4, too?