I have a home built in the late 60's. It is post and beam on 4 foot centers. The subfllor is 1 1/8 tounge and groove plywood. I am planning to put red oak floors 3/4 - 2 1/4 in the entire the house. Between each beam the subfloor sags approx 1/8 inch sometimes just a little more and I was wondering if this is going to cause a problem. Other than the slight sag the floor is generally pretty level and flat. Also what is the best way to lay the oak floor, perpendicular or parallel to the beams ? thanks