Q: No matter how expensive the prehung door, there always seem to be large differences in the spaces between the legs and head of the jamb and the door slab. How do you deal with those discrepancies?

A: John Spier, owner of Spier Construction, a building and remodeling company on Block Island, R.I., responds: I have often wished that prehung-door manufacturers would do more quality control. On just about every door I install, I find screws with stripped heads, as well as nails and staples driven into places where they’re visible. Manufacturers seem to fail to keep tools and jigs adjusted, so that the hardware is skewed or misaligned, and they always seem to stick adhesive labels on areas of the doors that will need to be cleaned and finished. I’ve also gotten doors that were hung upside down, and I’ve found snapped-off hardened screws holding double doors into a head jamb. So, those unequal gaps or reveals are the least of my complaints!

There are two ways to adjust the gap between the slab and the hinge jamb on a prehung door. The quick way is bending the hinge barrels over with an adjustable wrench.
There are two ways to adjust the gap between the slab and the hinge jamb on a prehung door. The quick way is bending the hinge barrels over with an adjustable wrench.

I don’t mind the top space being slightly larger than the side spaces, as long as the spaces are consistent; the extra room allows for future settlement and adjustment. In fact, one complaint I have with prehung doors is that they are often hung too tightly for a high-quality paint finish. To make room for multiple coats of paint between the jambs and the door edges, I usually find myself planing the hinge side of all the doors in the house before they’re painted.

Getting back to your question of how to adjust gaps once a door is hung, I learned a hinge-leaf-bending trick from a Gary Katz article long ago (“Hanging a New Door in an Old Jamb,” Aug/1999). To shrink a gap on the latch side, hold the head of a nail set between the leaves and gently close the door. As the hinge leaves bind on the nail set, they will spread slightly, which will push the door over and close the gap on the latch side.

If I need to shrink a gap on the hinge side, I pull the hinge pin in the offending area and gently bend the barrels of the jamb leaf slightly toward the jamb with a small adjustable wrench. When you replace the hinge pin, it then pulls the hinge side of the door over and shrinks the gap. One caution is that these methods work with stamped hinges (which most prehungs are equipped with); cast hinges will usually break before they bend.

A better method, which doesn’t distort the hinge, is removing the hinge and shaving a tiny bit off the mortise with a sharp chisel. Often, the mortise on only one side of the hinge needs to be shaved.
A better method, which doesn’t distort the hinge, is removing the hinge and shaving a tiny bit off the mortise with a sharp chisel. Often, the mortise on only one side of the hinge needs to be shaved.

I use these tricks occasionally for a quick fix, but I’m not keen on them. They can mar the finish, and distorting the hinges can cause the door to bind. Worst of all, altering the hinges like this can sabotage anyone who tries to remove the hinges in the future to repaint the door.

A better way of adjusting door reveals is to either shave the hinge mortises with a sharp chisel to narrow the gap on the hinge side, or pad out the hinges slightly to narrow the gap on the latch side. Often, only one of the leaves needs to be modified to make these adjustments. This strategy is fast and effective and doesn’t alter the shape of the hinges.