A.Gary Katz, a finish carpenter in Reseda, Calif.; moderator of JLC Online's finish-carpentry forum; and a frequent contributor to JLC, responds: I've installed thousands of hollow-core prehung doors in apartments, condominiums, and housing tracts — all without shims.

If the rough openings are sized 2 inches larger than the net door size, and if the door frame is roughly centered in the opening, the remaining gaps between the jambs and the framing are only 1/4 inch to 3/8 inch wide. Four 2 1/2-inch-long nails through the jamb at each hinge — a pair above and a pair below — and pairs of nails through the strike jamb about 14 inches on-center into the trimmers or jack studs, along with 2 1/2-inch nails through the casing into the studwalls, are more than enough to secure a hollow-core prehung door. A single 2 1/2-inch-long drywall screw through the top hinge and into the trimmer seals the deal.

The purpose of not using shims is for speed, though, not expansion. On the jobs I worked, I wasn't being paid for care, but for completion. Still, we never had callbacks and those doors still work fine.

However, if you're installing a solid-core door, whether it's prehung or not, always use shims. And for hollow-core doors in custom homes, shims are a good idea, too — who knows when someone will decide to switch out those lightweight doors for heavier ones.

On a standard 6'-8" door, I like to shim just beneath each hinge, and I put three sets on the strike side: one near the top of the door, one behind the strike, and one near the bottom. And on every door, I install long screws through the top hinges that sink securely into the trimmer.

Those screws do more to secure a door than any stack of shims or any number of nails.