Prehung vs. Slab Interior Doors: Installation Costs and When Each Wins
Prehung and slab are two ways to buy the same door -- and the labor arithmetic runs backward from expectations: prehung labor averages $120 to $260, slab-fitting labor $200 to $570 (2026 published data). A prehung door arrives mounted in its own frame with hinges attached; a slab is the panel alone, fitted into your existing frame. This guide compares the install types line by line so the frame condition -- not the price tag -- picks the winner.
Orange County, CA · Updated 2026 · Costs shown as ranges — your quote will vary by contractor and scope
What prehung and slab actually mean
A prehung door is the complete assembly: door panel, frame (jambs), and hinges, shipped as one unit -- set into the rough opening and shimmed plumb. The frame arrives square, hinge pockets pre-cut, lockset bore pre-drilled: panel and frame built together.
A slab door is the panel alone -- no frame, no hinges, no hardware attached. The installer hangs it in your existing frame: mortising hinge pockets, planing panel edges to fit the opening, and drilling the lockset bore to line up with the strike plate.
Prehung: $120 to $260 in labor, higher door price
Prehung labor averages $120 to $260 per door (2026 published data) because the path is efficient: pull the old unit, set the frame, shim it plumb, nail it off, hang the door, case the trim. Two to three hours when the opening cooperates -- the frame-in-a-box design is forgiving.
The tradeoff is the unit price: prehung costs more than the same panel as a slab, because you are buying the frame, hinges, and the factory alignment along with the door. Prehung is the bigger demolition: the old frame comes out, so trim, drywall edges, and paint all touch the project. Budget casing and patching when frame depths differ.
Slab: $200 to $570 in labor, lower door price
Slab-fitting labor averages $200 to $570 per door (2026 published data) -- the labor line inverts. The panel costs less, but fitting it to an existing frame is fiddly, skilled work: transferring hinge locations, mortising pockets, planing edges, and aligning the lockset bore with the old strike. Two to four hours -- the top of the band for frames that have settled or twisted.
Slab wins when the frame is good -- square, sound, the right size -- and on disruption: the trim, paint, and casing all stay. Slab loses when the frame is bad: fitting a panel into a twisted old frame is the most expensive door install per hour.
The frame-condition decision: square and sound, or replace it
This is answered with a level and a close look, not a price list. A frame worth keeping: jambs plumb within an eighth of an inch, no splits at the strike and hinges, the right size for the panel. A frame worth replacing: out-of-square enough that doors bind, split jambs, or a depth mismatch with the new trim.
Frame repair runs $51 to $141 per damaged section; full frame replacement runs $113 to $222 (2026 published data). Replacement turns the job into a prehung install -- price it that way from the start. The losing move: paying slab-fitting labor ($200-$570) into a frame that needed replacing anyway.
Adding a door to a new opening: the third path
Sometimes the project is a new door in a wall -- closing off a room, adding a bathroom door. Cutting an opening and installing a prehung door in a new interior wall runs $675 to $1,100 (2026 published ranges), depending on size, plumbing or wiring in the wall, and how much finish patching is needed.
This is a prehung job by default -- there is no frame to reuse. The band covers framing the opening, hanging the unit, casing, and patching drywall and paint. Plumbing or electrical in the wall climbs the band -- rerouting is a separate trade's bill.
Prehung vs. slab interior door installation (2026)
| Item | Prehung |
|---|---|
| What you buy | Door + frame + hinges, one unit |
| Unit price | Higher (frame included) |
| Install labor | $120 – $260 |
| Install time | 2 – 3 hrs |
| Trim / casing work | Old trim removed, new casing set |
| Frame condition needed | New frame -- always square |
| Disruption | Higher (frame comes out) |
| Frame replacement adds | — (frame included) |
| Frame repair, per section | — (frame included) |
| Fit / trim to opening | Factory-done |
| New opening in wall | $675 – $1,100 |
| Best when | Frame damaged / out of square / new opening |
DIY vs. hiring a pro
Check the frame before buying: level the jambs, look for splits at the strike and hinges, confirm standard widths. Prehung is the approachable DIY -- the square frame does the alignment work. Slab fitting, hinge mortising, and planing belong on the pro line.
What drives the price up or down
- Frame condition -- square and sound vs. damaged (the decider)
- Install type -- prehung $120-$260 labor vs. slab $200-$570
- Panel weight -- solid-core needs sturdier hinges and framing
- Opening work -- like-size swap vs. new opening ($675-$1,100)
- Hardware -- $20 to $100 per lockset, hinges on slab work
- Casing and trim -- replaced on prehung, kept on slab
- Disruption tolerance -- frame-out vs. frame-in-place
- OC labor -- coastal rates top every band
How to keep the cost down
- Let the frame decide: sound frame = slab; bad frame = prehung
- Price the stack, not the panel -- labor inverts the unit price
- Never pay slab-fitting labor into a frame that needs replacing
- Do multi-door visits: prehung crews are fastest on repeats
Frequently asked questions
Is a prehung door cheaper to install than a slab?
Usually yes on labor: prehung averages $120 to $260 vs. $200 to $570 for slab fitting (2026 published data). The slab panel costs less, but fitting it to an old frame is fiddly, skilled work.
When should I choose a slab door?
When the existing frame is square, sound, and standard-sized -- and you want to keep the trim and casing. Choose prehung when the frame is damaged, out of square, or the wrong size.
How much does it cost to replace an interior door frame?
$113 to $222 for a full frame replacement, or $51 to $141 per damaged section (2026 published data). A replacement frame turns the job into a prehung install.
Can I hang a slab door on an old frame myself?
The prehung swap is the approachable DIY -- the factory frame keeps alignment square. Slab fitting (mortising hinges, planing edges, aligning the bore) is skilled work; first-timers usually end up with a door that binds.
How much does it cost to add a door to an interior wall?
$675 to $1,100 for cutting an opening and installing a prehung door in a new interior wall (2026 published ranges). Plumbing or electrical in the wall adds a separate trade's bill.