I need to level my concrete slab floor before installing hardwood. The corner I need to level dips down 1 inch in about a 5 foot distance and heads into a sliding screen door, which needs to be replaced. Some of the floor leveling coumpounds say they level up to 1/2 inch, would compund not be a solution? Also ,should the door be taken out to level the floor? Thanks.

With a dip of that magnitude this application would be a perfect Job for self leveling portland cement. Remember to damn any where you don't want it to flow. But self leveling does not mean that you won't have to smooth it out. I usually go over it with a feather finish cement compound.