Prehung vs. Slab Doors: Which Should You Choose?
```A prehung door arrives mounted in its own frame, while a slab door is the door panel by itself. Both can produce a professional result, but they differ in cost, installation time, required carpentry work and suitability for the existing opening.
What Is a Prehung Door?
```A prehung door is supplied as a complete door unit. The slab is already attached to a frame with hinges, and the frame is designed to be installed into a prepared rough opening.
A prehung unit commonly includes:
- The door slab
- Side jambs and head jamb
- Hinges installed on the door and jamb
- A stop molding around the frame
- A prepared location for a latch or lockset
A prehung unit may not include:
- Door casing or decorative trim
- Knobs, levers or locks
- Fasteners and shims
- Paint, stain or clear finish
- A threshold for an interior doorway
Because the door and frame are matched at the factory, a prehung unit removes much of the precision work involved in positioning hinges and establishing consistent gaps around the slab. The installer must still level, plumb, square and securely fasten the new frame.
```What Is a Slab Door?
```A slab door is a standalone door panel without an attached frame. Depending on the product, it may be completely blank or partially prepared for hinges and a lockset.
Blank slab
A blank slab normally requires the installer to lay out and cut the hinge mortises, drill the lock bore, prepare the latch edge and trim the door when necessary.
Machined slab
A machined or pre-bored slab may already have hinge locations, a lock bore or other preparation. These locations must closely match the existing frame and hardware.
Slab doors provide greater flexibility, especially when preserving an existing frame, matching custom trim or creating a nontraditional door system. However, they require more accurate measuring and fitting.
```Prehung vs. Slab Door Comparison
```| Consideration | Prehung Door | Slab Door |
|---|---|---|
| What is included? | Door slab, frame and hinges | Door panel only |
| Best application | New construction or complete frame replacement | Replacing a door while keeping a sound existing frame |
| Initial product cost | Usually higher | Usually lower |
| Carpentry required | More work on the rough opening and frame installation | More detailed cutting, fitting and hardware preparation |
| Existing trim | Usually removed and reinstalled or replaced | Can often remain in place |
| Installation accuracy | Frame must be installed plumb, level and square | Slab must precisely match the existing opening |
| Customization | Limited by the supplied frame configuration | Well suited to custom sizing and alternative hardware |
| Typical skill level | Intermediate | Intermediate to advanced |
When a Prehung Door Is the Better Choice
```A prehung door is usually the practical choice when:
- The existing frame is split, twisted, rotted or badly worn.
- The door opening has recurring alignment problems.
- You are installing doors in new construction.
- You are adding a doorway to a newly framed wall.
- The existing hinge locations do not match the new door.
- You want the slab, hinges and frame supplied as one coordinated unit.
- The old jamb has been altered multiple times and no longer holds hardware securely.
When a Slab Door Is the Better Choice
```A slab door may be the better value when:
- The existing jamb is straight, solid and securely fastened.
- The current door operates correctly but needs a style update.
- You want to preserve existing casing, trim or historic millwork.
- The replacement slab closely matches the old door’s dimensions.
- You are comfortable laying out hinges and lock hardware.
- You need a panel for a pocket, bypass, bifold or barn-style installation.
- You are creating a custom door from a decorative or architectural slab.
Which Option Is Easier to Install?
```Neither option is automatically easy. The work is simply concentrated in different areas.
Installing a prehung door
The slab is already fitted to the jamb, but the entire assembly must be accurately positioned in the rough opening. Poor shimming can cause the door to swing open, rub the frame or fail to latch.
Installing a slab door
The existing frame remains in place, but the slab may need to be trimmed, beveled, mortised and drilled. Small layout errors can create uneven gaps or misaligned hardware.
For many do-it-yourself projects, a prehung door is more predictable when the entire opening needs work. A slab replacement can be faster when the old frame is square and the new slab closely matches the old door.
```How to Measure for a Prehung Door
```Prehung doors are selected primarily according to the rough opening and wall construction—not only the dimensions of the old slab.
- Remove enough trim to inspect the rough opening when possible.
- Measure the rough-opening width in several locations.
- Measure from the subfloor or finished floor to the framing header.
- Determine the wall thickness so the jamb depth will fit correctly.
- Confirm the desired door width and height.
- Identify the required handing and swing direction.
- Check whether flooring will be installed or changed before final installation.
How to Measure for a Slab Door
```When replacing an existing slab, the old door is usually the most useful template—provided it fit and operated correctly.
- Measure the exact width, height and thickness of the old door.
- Record the location and size of every hinge.
- Measure hinge locations from the same reference point, normally the top of the door.
- Measure the lock-bore diameter and backset.
- Record the latch location on the door edge.
- Check whether the door edge has a bevel.
- Mark the top, bottom, hinge side and latch side before removing the old slab.
Understanding Door Handing and Swing
```Door handing can be confusing because terminology is not always used consistently. Before ordering, determine:
- Which side of the opening will hold the hinges
- Which room the door will swing into
- Whether the swing will interfere with furniture, switches or fixtures
- Whether local building requirements affect the swing direction
A simple approach is to draw the doorway from above and mark the hinge side and swing arc. Use that drawing when confirming the order with the supplier.
```Cost: Look Beyond the Door Price
```A slab typically has a lower purchase price because it does not include a frame. However, total project cost may include additional labor or tools for fitting and hardware preparation.
Possible prehung expenses
- Removal of existing jambs and casing
- New trim or casing
- Wall and paint repairs
- Shims and installation fasteners
- Professional installation
Possible slab-door expenses
- Hinge-mortising tools
- Lock-boring tools
- Planing or trimming
- New hinges and lock hardware
- Additional fitting labor
Compare the total installed cost rather than the price of the door alone. A low-cost slab may not be the least expensive option if extensive fitting is required.
```Can a Slab Door Be Used as a Pocket Door?
```Yes. Pocket doors commonly use door slabs because the supporting frame and track are separate from the door panel. The slab must be compatible with the selected hardware, including its thickness, weight, width and height.
A pocket-door slab may also require preparation for hanger plates, guides, a flush pull or an edge pull. Always check the hardware specifications before cutting or drilling the door.
Can a Prehung Door Be Converted to a Slab?
```The slab can usually be removed from a prehung assembly and used separately, but buying a complete unit only to discard the jamb is rarely economical. Factory hinge machining and lock preparation may also be unsuitable for the intended opening.
Purchase a slab directly when the project uses pocket, bypass, barn-door or other track-mounted hardware.
```Door Material Matters Too
```The prehung-versus-slab decision describes how the door is supplied. It does not describe the door’s internal construction. Either option may be available with:
- Hollow-core construction: Lightweight and economical for many closets and low-traffic rooms.
- Solid-core construction: Heavier, more substantial and generally better at reducing sound transfer.
- Solid wood: Traditional appearance with natural variation and refinishing potential.
- Molded composite: Available in many panel designs with consistent factory construction.
- Glass panels: Useful where light, visibility or decorative impact is important.
Check the door’s actual weight before selecting hinges, pocket-door hangers or other supporting hardware.
```Common Buying Mistakes
```Ordering by slab size alone
A prehung unit must fit the rough opening and wall thickness. The slab’s labeled dimensions do not represent the complete frame size.
Ignoring the floor height
New tile, wood or carpet can change the required bottom clearance and may affect whether the door can swing freely.
Assuming hinge locations are standard
Hinge spacing can vary by manufacturer, door height, age and project specifications.
Buying hardware too early
Confirm door thickness, weight, preparation and intended use before ordering hinges, pulls, locks or track systems.
Overlooking jamb depth
A frame made for one wall thickness may not align correctly with the finished surfaces of another wall.
Keeping a damaged frame
Installing a new slab in a twisted or loose jamb often transfers the old problems to the new door.
A Simple Decision Guide
```Choose a prehung door when:
The frame is damaged, the opening is new, the existing geometry is unreliable or you want a coordinated door-and-frame assembly.
Choose a slab door when:
The frame is in excellent condition, the replacement closely matches the existing door or the slab will be used with track-mounted hardware.
Ask a carpenter or installer when:
The opening is noticeably out of square, the door has an unusual size, the wall may be structural or the project requires extensive frame modification.
Hardware and Related Products
```The correct hardware depends on whether the slab will swing, slide, fold or move into a wall pocket. Measure the door and review the hardware requirements before ordering.
Door Hinges
Swinging slab doors require hinges that are appropriate for the door’s thickness, weight and frequency of use.
Shop Door HingesPocket Door Frame Kits
A compatible slab can be paired with a pocket-door frame kit to eliminate the floor space required by a swinging door.
View HBP Pocket Door Frame KitsPremium Pocket Door Kits
Larger and heavier slabs may require a higher-capacity frame and track system designed for the door’s weight.
View Premium Pocket Door KitsInterior Thresholds
A hardwood threshold can create a finished transition where flooring materials or floor heights change beneath a doorway.
Shop Interior ThresholdsFrequently Asked Questions
```Is a prehung door always more expensive?
Its purchase price is usually higher because it includes the frame and hinges. However, the total installed cost may be competitive when a slab would require extensive fitting or frame repair.
Can I replace a prehung door with only a slab?
Yes, provided the existing frame is sound and the new slab can be fitted to the opening. Carefully compare the dimensions, hinge positions, lock preparation and door thickness.
Do prehung doors include knobs or levers?
Not necessarily. Many are prepared for lock hardware but do not include the knob, lever or lockset. Confirm the product description before ordering.
Do slab doors come with hinge mortises?
Some do, but many are blank. Even a factory-machined slab may not match the hinge locations in an older frame.
Can a slab door be trimmed?
Many slabs permit limited trimming, but allowable amounts depend on their construction and manufacturer. Hollow-core and molded doors may have narrow perimeter blocks that limit how much material can be removed.
Which option is better for a remodel?
Use a slab when the existing frame is square, sturdy and worth preserving. Use a prehung unit when the old frame is damaged, poorly aligned or being removed as part of the remodel.
The Bottom Line
```A prehung door provides a new slab, frame and hinge setup in one assembly. It is generally the better choice for new openings and complete replacements. A slab door preserves the existing frame and provides more flexibility, but it demands accurate measuring and hardware preparation.
Before buying, inspect the frame, measure the opening carefully, identify the swing or sliding configuration and consider the total installation cost. The right choice is not simply the less expensive door—it is the option that best fits the condition of the opening and the skills required for the project.
```