A slab replaces the door panel while keeping a compatible existing jamb; a prehung unit arrives with the slab attached to a new frame. Choose after checking the old jamb, door dimensions, hinges, lock preparation, swing and how much casing or wall finish the project includes.
Replacing only the door slab can preserve sound casing and an existing jamb, but the new panel must match the frame and hardware. A prehung unit replaces the panel and frame together, which can make sense when the jamb is damaged or the opening is being rebuilt. Inspect the opening before choosing.
Compare the two replacement paths
| Option | What is replaced and what to check |
|---|---|
| Slab | The door panel only. Inspect the jamb and verify the panel’s dimensions, thickness, handing, hinge positions, latch preparation and floor clearance. |
| Prehung | The panel and its new frame as a coordinated unit. Check the rough opening, jamb depth, handing, swing, casing and any wall or floor repair. |
Masonite describes a prehung door as a slab attached to the frame and a slab as the panel alone. Some packages include additional hardware or components, so confirm the contents of the specific unit you are buying.
Choose a slab when the existing jamb is a good fit
A slab can avoid removing the frame and casing when those pieces are in good condition and the new door can be fitted to them. Before ordering, record the old slab’s width, height and thickness. Check that the jamb is straight, secure and square enough for the replacement, and identify the hinge mortises, latch bore, door swing and under-door clearance.
Do not assume two panels with the same nominal size will match. Hinge locations and hardware preparation can differ. Masonite recommends measuring the opening and jamb for a replacement and checking handing and swing. Ask the supplier or installer to compare the old door and new panel before any cutting or drilling.
Choose prehung when the frame is part of the repair
A prehung unit is a stronger candidate when the jamb is damaged or out of alignment, or when the project includes changes to the opening. The installer removes the existing unit and sets the new frame in the rough opening. That can add casing, wall finishing, paint, flooring or disposal work to the project, depending on what is being replaced.
Measure the rough opening and wall depth, and verify the door’s handing and swing before ordering. The manufacturer’s measurements describe its products; an installer should verify the actual opening and installation instructions at the home.
Compare the complete job
Ask for two itemized options if both are feasible: one slab fitted to the existing jamb and one prehung replacement. Include the panel or complete unit, hardware, hinge or latch preparation, frame work, casing, painting, disposal and any floor or drywall repair. Compare who measures and takes responsibility for a fit problem.
If the opening is an exterior door or part of a required fire or smoke separation, check the applicable requirements and compatible assembly before replacing only a panel. For exterior systems, compare fiberglass, steel and wood entry-door materials and use the product’s full installation details. See how to hire a remodeling contractor before choosing the installation scope.
Sources
- Masonite: Prehung and slab door options
- Masonite: How to measure for interior doors
- Masonite: How to install interior doors
- JELD-WEN: Interior door slab installation instructions
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Common questions
What is included with a prehung interior door?
A prehung unit includes a door slab already attached to a frame, usually with hinges installed. Confirm the exact package, jamb depth, handing, swing and hardware with the manufacturer or retailer.
Can I replace only the slab?
Often, if the existing jamb is sound, plumb and compatible with the new slab. Match the width, height, thickness, hinge locations, latch preparation, swing and clearance before ordering.
Is a slab door easier to install than a prehung door?
Neither choice is always simpler. A slab can require fitting and hardware work in the existing jamb; a prehung unit requires setting and aligning a new frame in the rough opening. The condition of the opening and the installer's scope matter.
What should a door replacement quote include?
Ask whether it covers the slab or complete unit, frame repair or removal, hinge and lock preparation, casing, paint, disposal, hardware and any needed changes to the opening.