The sweep on the door bottom is even easier to replace.
My front door has a gap at the bottom.
Pull the weatherstripping toward the outer edge of the door.
Examine the weatherstripping on the bottom of the door to see if there are holes or worn areas.
If the gap along the latch side of your door is allowing unwanted air to infiltrate your space or letting expensive heat or cooled air out weatherstripping can help reduce or eliminate this space.
Open the exterior door.
Door sweeps reinforce the seal between the bottom of the door and the door jamb meaning you get extra protection from dirt bugs moisture and wind.
I have never seen a door set with that big of a gap unless it was to get past floors that were not level.
All purpose door sweeps generally made of a metal brace and a vinyl weatherstripping piece can close the gap and keep cold air and water outside.
Pry or slide out the old sweep.
That is a lot of room for unlevel you have there.
Run a bead of caulk along the bottom edge of the door tap the sweep into place and then staple it at the ends photo 4.
Imho you hold the cash have them fix it only then they will receive the next payment.
Be careful not to overdo it and seal the door so that it can t settle with the rest of the house.
A gap between the bottom of the front door and the threshold is easily fixed with a door sweep.
While you re at it you might as well do a quick fine tune of the adjustable threshold.
As long as the gap is even on an interior door it shouldn t be why a door isn t closing properly.