The filler piece will be 1 1 2 in.
Extending the length of a door.
Make sure the door is closed and take out the measuring tape.
Draw vertical lines on one wall with a straightedge and pencil that are 6 inches or more from each outer edge of the door opening.
Measure where the door meets the floor when it is closed.
Carefully cut off the door at the pencil mark to get a clean square edge.
Clearance under the door.
When you can see daylight under your door it is not the right size and needs to be.
Measure the distance between the bottom of the door and the floor.
Now we have a big gap from door to floor.
Remove the door by pulling out the hinge pins and lay it on a pair of padded sawhorses.
Years ago we removed all the carpeting in the house.
Check all the way across in case one area is uneven in measurement.
To seal out weather insects and dirt it is important to properly size your door.
Make a light pencil mark on the door 2 in.
Tall and you ll want at least 1 2 in.
For that you need to subtract at least a 1 8th of an inch for clearance.
How to fix a too short door.
Up from the floor at the high spot.
This is the size of the gap but not the size of the extra piece you are going to need.
If there is carpet flooring remove a 1 4 inch space from the total measurement for easement from the carpet to the door bottom.