To mark the bottom of a door for trimming so you have a 1/2″ gap between the door and floor:
- Put a piece of 1/2″ plywood on the floor on the hinge side of the door jamb.
- Measure the distance from the plywood to the bottom of the hinge on the door jamb.
- Measure the same distance from the bottom of the hinge on the door.
- Mark and cut the door to that length to leave a 1/2″ gap under the door.
Use a thicker piece of plywood for a larger gap under the door. Watch this video to find out more.
- How to Trim a Door (video)
- How to Trim a Hollow Core Door (article)
- How to Cut Door Jambs Around Flooring (video)
Joe Truini: After installing a new floor, there’s one more important step you have to make, and that is to trim the bottom of the doors so that they clear the new flooring. In this case we have a new tile floor put down, including this threshold. So I need to trim the door so it goes over that.
And I’m going to start with is a small block of half-inch plywood. I like using half-inch because that represents the clearance space beneath the door. So you just set the block in place, then measure from the wooden block up to the bottom edge of this hinge plate, and that is about nine and a half inches. Now, we just transfer that measurement to the door itself. And again, using that same reference point, the bottom edge of the hinge, just mark it at nine and a half inches. Here we go.
Now, I’ll just square that line along. Now, if you cut right on that line you’ll end up with a door with exactly half inch clearance space beneath it.