Replacing an interior door sounds straightforward until you start shopping and encounter two very different options: a door slab and a prehung door.
They may look similar in a product listing, but they are not interchangeable purchases. A slab is essentially the door itself. A prehung door is supplied as a more complete door-and-frame configuration, making it a fundamentally different solution for installation.
Choosing the right configuration depends on what you are replacing, the condition of the existing frame, how much of the opening is changing, and how much preparation you want to handle before installation.
Before ordering a replacement interior door, determine whether you are replacing only the door or the entire door-and-frame assembly. That decision affects what you need to measure, what hardware and preparation are required, and how involved the installation will be.
What Is a Door Slab?
A door slab is the individual door panel without the surrounding frame or jamb assembly.
If you picture a typical interior doorway, the slab is the part that swings open and closed. The jamb, casing, hinges, and other components are separate.
A slab can be the right configuration when the existing frame is staying in place and the new door needs to fit that opening. It can also be useful when a project calls for custom machining or other preparation before the door is installed.
Depending on the door and project, a slab may arrive unfinished or require additional preparation before installation. That can include finishing, hinge preparation, lock preparation, or other machining.
This makes slab doors particularly relevant for renovation projects where an existing frame is being retained.
What Does a Slab Door Include?
The important distinction is that a slab is not a complete doorway assembly.
A typical slab purchase does not automatically include:
- Door jambs
- Door casing
- Hinges
- Lockset
- Strike plates
- Installation labor
- An existing-frame replacement
The exact configuration can vary by product, so the product specifications should always be reviewed before ordering.
If you are replacing only the door panel and keeping the existing frame, you need to make sure the new slab is compatible with that frame.
That means dimensions, swing, hinge locations, thickness, and hardware preparation can all matter.
What Is a Prehung Door?
A prehung door is a door that has already been mounted to its frame or jamb assembly.
Instead of purchasing only the moving door panel, you are purchasing a more complete configuration designed to be installed as a unit.
For projects where the existing frame is being removed or replaced, a prehung door can simplify the process because the door and jamb are prepared together.
At Darpet, a prehung configuration includes the full jamb set and hinge hardware. The lockset and strike plates are not included.
That distinction is important when budgeting and preparing for installation.
What Does a Prehung Door Include?
A prehung configuration generally brings together the major components needed to install the door within a prepared opening.
For Darpet's prehung doors, this includes:
- Door slab
- Full jamb set
- Hinge hardware
The lockset and strike plates are separate.
Casing and other trim can also be purchased separately depending on the project requirements.
The advantage is that the door and jamb are configured together rather than requiring the installer to adapt a new slab to an existing frame.
Door Slab vs. Prehung: What's the Difference?
The simplest way to understand the difference is to think about what is being replaced.
| Consideration | Door Slab | Prehung Door |
|---|---|---|
| Door panel | Included | Included |
| Jamb/frame | Not included | Included |
| Hinges | Not automatically included | Included with Darpet prehung configuration |
| Lockset | Not included | Not included |
| Strike plates | Not included | Not included |
| Existing frame | Typically retained | Typically replaced |
| Installation scope | More focused on the door | Includes door and jamb assembly |
| Best fit | Existing frame remains usable | Frame/opening is being replaced or substantially changed |
Neither configuration is universally appropriate. The right choice depends on the condition of the existing opening and the scope of the renovation.
When Does a Door Slab Make Sense?
A slab can make sense when the existing frame is in good condition and you want to change the appearance of the door without rebuilding the entire opening.
This is common in renovation situations where the existing jamb and casing are worth keeping.
For example, imagine a homeowner has several interior doors with solid, serviceable frames but wants to update the door style throughout the house. Replacing the slabs can potentially provide the desired design change without removing every jamb and piece of surrounding trim.
A slab configuration may also make sense when:
You Are Keeping the Existing Frame
If the existing jamb is square, structurally sound, and compatible with the replacement door, there may be no reason to remove it simply to replace the door panel.
However, compatibility needs to be verified before ordering.
You Want to Minimize the Scope of the Renovation
Removing an existing frame can affect surrounding casing, drywall, paint, and other finish work.
Keeping the frame can reduce the physical scope of the replacement, although the existing opening still needs to be measured carefully.
You Are Replacing Doors Without Changing the Openings
A renovation may call for new door styles while leaving the existing rough openings and frames unchanged.
In that situation, a slab-focused approach may fit the project better than replacing complete door assemblies.
You Have a Custom Machining Requirement
Some slab projects require specific preparation for the existing installation.
Before ordering, determine exactly what machining and hardware preparation the installation requires.
A slab replacement is not simply a matter of measuring the height and width of the old door. Hinge locations, thickness, handing, hardware preparation, and the condition of the existing frame can all affect compatibility.
When Does a Prehung Door Make Sense?
A prehung door becomes more relevant when the frame is part of the renovation.
If the existing jamb is damaged, poorly fitted, or being removed as part of a larger remodel, replacing the door and jamb together can create a more complete installation.
A prehung configuration is also commonly considered in new construction, major renovations, and projects where multiple openings are being rebuilt.
You Are Replacing the Existing Frame
If the jamb is being removed, purchasing only a slab leaves you with another component to source and prepare.
A prehung configuration combines the door and jamb into one ordered assembly.
You Are Building New Openings
New construction and major remodeling projects often involve openings that do not already have finished interior door assemblies.
A prehung configuration can provide the door and jamb components needed for that portion of the project.
You Want the Door and Jamb Configured Together
With a prehung door, the door is already associated with its jamb configuration.
This can make sense when the project calls for a coordinated installation rather than adapting a new slab to an existing frame.
Multiple Doors Are Being Replaced
For a larger renovation, consistency can become an important consideration.
Using a defined prehung configuration across multiple openings can help contractors and builders plan door sizes, jamb requirements, swings, and hardware preparation as part of the overall door package.
What Should You Measure Before Ordering a Slab?
One of the biggest mistakes in a slab replacement is assuming that the existing door itself provides all the information needed for the new door.
Before ordering, document the existing installation carefully.
Important information can include:
- Door height
- Door width
- Door thickness
- Hinge locations
- Hinge size
- Door handing
- Lock and hardware preparation
- Existing frame dimensions
- Jamb condition
- Casing and trim conditions
The goal is to establish whether the new slab can actually work with the existing opening.
If the existing frame is out of square, damaged, or significantly different from the new door requirements, a prehung configuration may need to be considered instead.
What Should You Measure for a Prehung Door?
Prehung installations require a different approach because the jamb becomes part of the configuration.
Rather than measuring only the existing slab, the project needs to account for the entire opening and the wall construction around it.
Depending on the project, relevant measurements can include:
- Rough opening dimensions
- Existing jamb dimensions
- Wall thickness
- Door height and width
- Door swing and handing
- Casing requirements
- Finished-floor conditions
- Clearance requirements
The jamb depth is especially important because it needs to correspond with the wall construction and finished opening.
This is one reason prehung door selection should happen early enough in the remodeling process to coordinate with framing, drywall, flooring, and trim.
Don't Confuse the Door Configuration With the Door Style
A common source of confusion is treating slab vs. prehung as though it describes the appearance of the door.
It does not.
Slab and prehung describe the configuration.
The actual door style is a separate decision.
For example, a project could use a Shaker-style door, a Flush door, a Caiman or Carrara panel door, or another design as either part of a slab-oriented project or a prehung configuration, depending on the available product and project requirements.
That means your selection process should happen in two stages:
- Choose the door style and material.
- Determine whether the project requires a slab or prehung configuration.
This separation makes the ordering process much clearer.
How Trim Fits Into the Decision
Door replacement rarely ends with the door itself.
Casing and baseboard can have a major effect on the finished appearance, especially when a frame is being removed.
A slab-only replacement may allow existing casing to remain in place if the existing frame is retained.
A prehung replacement, however, may require surrounding trim to be removed and reinstalled or replaced depending on the installation.
Before ordering, consider the complete opening:
Door → Jamb → Casing → Baseboard → Hardware
Treating these components as one coordinated package can help avoid surprises during installation.
This is also where door and trim selections should be coordinated. A new door can look out of place if its proportions or style conflict with the existing casing and surrounding architectural details.
What About Hardware?
Hardware is another area where the difference between slab and prehung becomes important.
A door needs more than the panel itself to operate.
Depending on the configuration, you may need to plan for:
- Hinges
- Knobs or levers
- Locksets
- Strike plates
- Other hardware components
Darpet's prehung configuration includes hinge hardware, but locksets and strike plates are not included.
With a slab, hardware preparation and existing hinge compatibility become particularly important because the installer may need to adapt the new door to the existing frame.
Hardware should therefore be considered before the door is ordered rather than treated as a final detail.
Slab or Prehung? Start With the Existing Opening
If you are unsure which configuration to purchase, start with the opening rather than the product catalog.
Ask these questions:
1. Is the existing frame staying?
If yes, investigate a slab replacement.
If no, a prehung configuration may be more appropriate.
2. Is the existing jamb in good condition?
A damaged, poorly fitted, or unsuitable jamb can change the decision.
3. Are the door dimensions compatible?
Do not assume that a replacement slab will automatically match the existing frame.
4. Are you changing the trim?
If casing and surrounding trim are being replaced anyway, a larger door-and-frame renovation may make sense.
5. Is this new construction or a major remodel?
A prehung configuration is often more relevant when the opening itself is being constructed or substantially rebuilt.
6. What does the installer expect?
If a contractor is handling the installation, confirm the required configuration before placing the order.
Common Mistakes to Avoid
Ordering a Slab Without Checking the Existing Frame
The new door may have the correct overall dimensions but still fail to work with the existing hinge or hardware locations.
Assuming a Prehung Door Includes Everything
A prehung door is more complete than a slab, but it does not necessarily include every piece of hardware or trim.
For Darpet, the prehung configuration includes the full jamb set and hinge hardware. Locksets and strike plates are separate.
Measuring Only the Door
The surrounding frame and opening matter, particularly when ordering a prehung configuration.
Forgetting Door Swing
Handing and swing direction should be documented before ordering, especially when multiple doors are being replaced.
Ignoring Wall Thickness
Jamb requirements are tied to the wall construction. This should be verified rather than estimated.
Treating Trim as an Afterthought
Replacing the door and frame can affect casing and surrounding finish work. Plan the complete opening rather than treating the door as an isolated component.
The Bottom Line
The difference between a door slab and a prehung door comes down to the scope of the installation.
A door slab is the door itself. It can be a practical configuration when the existing frame is staying in place and the new door can be properly fitted to that opening.
A prehung door combines the door with its jamb assembly. It can make more sense when the existing frame is being replaced, when a new opening is being built, or when the project calls for a coordinated door-and-jamb configuration.
The most important step is to determine what is actually changing in the doorway before you order.
If the renovation is limited to the door panel, start by carefully documenting the existing frame and hardware locations. If the frame is part of the renovation, plan for the complete opening—including jamb, casing, hardware, and finished-floor conditions.
For homeowners, builders, and contractors, understanding this distinction before ordering can prevent mismatched components, unnecessary work, and installation delays.
Darpet offers both door slabs and prehung door configurations, allowing the door configuration to be considered alongside the style, dimensions, and requirements of the project.
Frequently Asked Questions
Is a slab door the same as a prehung door?
No. A slab is the individual door panel, while a prehung door includes the door mounted within a jamb or frame assembly.
Does a prehung door include the lockset?
Not necessarily. Darpet's prehung configuration includes the full jamb set and hinge hardware, but locksets and strike plates are not included.
Can I replace only my interior door and keep the frame?
Potentially. A slab replacement can work when the existing frame is in suitable condition and the new door can be properly fitted to it. Measurements and compatibility should be verified before ordering.
Is a prehung door better for new construction?
A prehung configuration can be useful when the door opening is new or when the existing frame is being replaced. The appropriate configuration depends on the project's framing, wall thickness, dimensions, and installation requirements.
Do I need new trim when replacing an interior door?
Not always. If the existing frame and casing remain, existing trim may be retained. If the jamb is being replaced, casing and surrounding finish work may need to be removed, reinstalled, or replaced.
What should I measure before buying a replacement door?
For a slab replacement, document the door dimensions, thickness, hinge locations, handing, hardware preparation, and existing frame dimensions. For a prehung door, the rough opening, wall thickness, jamb requirements, and overall opening configuration become important as well.