A visible door gap between the door and door frame.
Gap under new front door.
Make marks through the pre drilled attachment holes onto the door proper.
Water leaking from the top of the door frame.
Open the door and place a wooden block or hardback book under the outer corner of the door to hold it in place while you work.
Place the sweep at the bottom of the door and align the sweep edge so that it blocks the door gap.
If you have a large gap at the bottom of your door that may be helping the door to stay plumb.
Pilot hole the marks.
Water leaking around the door or water leaking under the door or door bottom.
As long as the gap is even on an interior door it shouldn t be why a door isn t closing properly.
A drafty door with chilly drafts air blowing through your entryway.