Prehung vs. slab interior doors: which to order

Builders ask us this one all the time: do I order prehung or slab? Get it wrong and you've either paid for jambs you'll throw away or signed your finish crew up for a day of fiddling that didn't need to happen. The answer depends on the opening, the schedule, and what kind of trim you're hanging next to it.

Here's the plain version. A prehung door comes already mounted in its own jamb, hinges set, ready to drop in a rough opening. A slab is just the door — no jamb, no hinges, no holes. Both have a place on a job. This breaks down when each one earns its keep.

What you're actually ordering

Know the parts before you spec it. A prehung interior door ships as a unit: the slab, a three-sided jamb, the hinges already mortised and screwed, and usually the doorstop applied. Some come split-jamb so the casing's pre-attached on both faces. You shim it plumb in the rough opening, fasten through the jamb, and you're hung.

A slab is the door and nothing else. You're supplying or reusing the jamb, mortising for hinges, boring for the latch and strike, and hanging it by hand. More steps, more skill, but more control over the final fit.

When prehung is the right call

On new construction, prehung wins most of the time. The opening's a bare rough frame, you've got a stack of doors to set, and speed matters. A prehung unit lets your finish crew move room to room without mortising a single hinge.

• New builds and big door counts — when you're hanging a whole house, the labor saved adds up fast.
• Fresh rough openings — no existing jamb to match or save, so the prehung jamb just slots in.
• Consistent reveals — factory-hung hinges mean the gaps come out even with less hand-fitting.
• You want casing to follow right behind — once it's set plumb, you're ready to case and trim.

When slab is the smarter buy

Slab earns its place in remodels and any spot where the jamb already exists and you want to keep it. Tearing out a sound, finished, cased jamb to shove in a prehung is wasted work — and it tears up the wall around it. If the opening's plumb and the jamb's good, a slab drops the cost and saves the surrounding trim.

• Remodels with existing jambs — keep the jamb and casing, swap the door.
• Odd or out-of-square openings — a slab gets scribed and trimmed to fit what's really there.
• Specialty or oversized doors — solid-core, tall doors, or a one-off that doesn't come prehung.
• Matching an old-house jamb thickness — when a standard prehung jamb won't line up with plaster or thick walls.

Rule of thumb: bare rough opening, order prehung. Existing finished jamb you want to keep, order the slab.

The jamb is where it lives or dies

Prehung or slab, the door is only as good as the jamb behind it. A jamb that's out of plumb gives you a door that swings open or shut on its own, gaps that taper, and a latch that won't catch. With prehung, that means taking real care shimming — don't trust the factory to make up for a racked rough opening. With slab, it means checking the existing jamb is plumb and square before you ever touch the door, then mortising clean so the hinges sit flush.

Either way, the door jamb thickness has to match your wall, and the casing has to land flat against it. That's why doors and casing get planned together — if you're still deciding profiles, our door and window casing styles notes pair with this one. And when you're building the rest of the trim package around these openings, see how it ties to moulding & trim.

How we spec it on a job

Walk the openings first. New construction with bare framing, we lean prehung for the speed and even reveals. Remodel with jambs worth saving, we go slab and protect the existing trim. Mixed jobs get a mix — there's no rule that says the whole house has to be one or the other. The goal is a door that swings true, latches clean, and sits in casing that looks like it grew there.

Got a door schedule and not sure how to spec it? Send the plans and we'll tell you prehung or slab, opening by opening — see the full scope on our interior doors page.