Nail it to one of the doors using small wood nails so that it overlaps the other door by about one half inch covering the gap.
How much of a gap between french doors.
Unlike interior doors gaps between a front door and a frame must go with the standards not so much due to the possible expansion of a leaf but because of the danger of penetration of cold air and extraneous sounds from outside.
I ve installed many pre hung interior french doors with great success.
Do this on both doors.
It s not uncommon for a gap or crack to exist where the two doors come together.
So if the doors are 24 inches wide leave a 1 4 inch gap between doors and between each door and the jamb.
This adjustment works well if you have a gap between the french doors or the latch mechanism doesn t connect.
Gaps between a front door and a frame.
Place nails about every 5 inches.
Because one or both of the french doors are moving many traditional weatherstripping solutions just don t apply.
When calculating the width remember there are three gaps between the doors instead of two plus a jamb on each side of the opening.
Cover the nail heads with wood putty and sand them smooth.
Double interior french doors are hard to install because you have additional tolerances you must satisfy to make the install look professional.
Turn the upper hinge adjustment screw to even out the gap.