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
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.