If you are shopping for interior doors for the first time or planning a renovation, you will quickly encounter two options: prehung and slab. What is a prehung interior door, and how does it differ from a slab? Understanding the difference matters because it determines how much installation work is involved, whether an existing frame can be reused, and what additional materials you need to purchase. This guide covers both questions and explains when a prehung interior door is the right choice for your project.
A prehung interior door is a complete unit that comes with the door slab, a three-sided frame (two vertical jambs and a header), and pre-attached hinges. Most units also include pre-drilled holes for the lockset and latch. Unlike a slab door, which is just the panel, a prehung interior door is ready to install directly into a rough opening without reusing an existing frame.
What a Prehung Interior Door Includes
What are prehung interior doors made up of? This type of door is sold as a pre-assembled unit, meaning several components that would otherwise need to be sourced and fitted separately come ready to install. Knowing exactly what is included prevents surprises at the project stage and allows for accurate material budgeting before work begins.
|
Component |
What It Is |
Typically Included? |
|
Door slab |
The panel itself , the actual door surface, in hollow or solid core construction |
Yes |
|
Door jamb (frame) |
Three-sided frame: two vertical legs (jambs) plus a header across the top |
Yes |
|
Hinges |
Pre-mortised into both the door slab and jamb, factory-aligned for correct swing |
Yes |
|
Lockset bore hole |
Hole bored through the door face for the handle or knob hardware |
Yes, on most units |
|
Strike plate mortise |
Recess cut into the jamb for the latch strike plate |
Yes, on most units |
|
Stop molding |
Thin strip inside the jamb that the door panel closes against when latched |
Yes, integrated into jamb |
|
Door casing / trim |
Decorative molding covering the gap between jamb and wall on both faces of the opening |
Not always , confirm before ordering |
Every unit includes the slab, frame, and hinges. Pre-drilled hardware holes are standard on most units. The one component that is not always included is the door casing, which is the decorative trim covering the gap between the frame and the surrounding wall. Always confirm whether casing is included before ordering, and budget for it separately if it is not.
A Note on Door Casing
Casing is the decorative trim molding that covers the gap between the door jamb and the surrounding drywall on both sides of the wall. It is visible every time you walk through a doorway, which makes it an important aesthetic component. Some prehung interior door units include casing as part of the package; others ship the frame and panel only, leaving casing as a separate purchase. When ordering a prehung interior door, confirm whether casing is included in the unit description. If it is not, casing is measured and cut on-site to fit the specific wall thickness and installed after the prehung unit is set and fastened.
See more: Types of Interior Doors: Every Style, How They Work, and Which Room They Suit
Standard Prehung Interior Door Sizes
Prehung interior doors are manufactured in standard dimensions that correspond to common rough opening sizes in US residential construction. Knowing the standard sizes before measuring your opening helps confirm whether a standard unit fits or whether a custom size is required.
Standard Heights
The most common prehung interior door height in the US is 80 inches, which suits homes built with standard 8-foot ceilings. An 84-inch height is available for transitional or slightly taller ceiling heights, and a 96-inch option suits homes with 9-foot or 10-foot ceilings where standard 80-inch doors would look visually undersized relative to the wall height. When in doubt, measure the existing door opening from the subfloor to the underside of the header and confirm which height best matches the space.
Standard Widths
Single prehung interior doors are most commonly available in widths of 24, 28, 30, 32, and 36 inches. The 28-inch and 30-inch widths suit bathroom and secondary room openings. The 32-inch width is the most common for bedroom doors. The 36-inch width provides additional clearance and is often specified in master bedrooms, home offices, and accessibility-focused renovations where extra passage width is a requirement. Double prehung configurations, where two panels are mounted in a single wider frame, are available in total widths from 48 to 72 inches and suit formal dining rooms, living areas, and any opening where a wider passage or a French door aesthetic is the goal.
Rough Opening and Clearance
The rough opening must be sized to accommodate the prehung unit plus a clearance allowance for shimming. As a general rule, the rough opening should be approximately 2 inches wider and 2 inches taller than the door unit dimensions to provide room for adjustment. A 32-inch prehung interior door, for example, requires a rough opening of approximately 34 inches wide. Always confirm the specific clearance requirement with the manufacturer or supplier, as tolerances vary by product and frame thickness.
See more: Best Way to Paint Interior Doors: Tools, Prep, and Technique for a Pro Finish
Prehung vs Slab Interior Doors: Side-by-Side Comparison
The choice between a prehung and a slab interior door is the most important decision in any door replacement or renovation project. The two options look identical once installed, but the installation process, cost, and project requirements are significantly different.
|
Criteria |
Prehung Interior Door |
|
|
What is included |
Door slab, frame (jamb), hinges, pre-drilled hardware holes |
Door panel only |
|
Frame requirement |
Installs in rough opening; no existing frame needed |
Requires existing frame that is level, plumb, and square |
|
Installation complexity |
Moderate: shim and level the full unit in the rough opening; two-person job |
Higher precision: hinge mortises, lock holes, and fit must align exactly with existing frame |
|
Best used when |
New construction; damaged or out-of-square existing frame; full renovation |
Existing frame is in good condition; trim and casing to be preserved |
|
Relative cost |
Higher , frame is included in the purchase price |
Lower , panel only; existing frame is reused |
|
Installation time (approx) |
1 to 3 hours per door with a helper |
2 to 4 hours per door; more precision carpentry required |
|
Disruption to existing trim |
High , all casing on both sides must be removed and reinstalled |
Low , existing casing can often be preserved |
Prehung interior doors are the more complete and installation-ready option, but they require removing and replacing the entire door frame, which involves reinstalling all casing. Slab doors are more economical and less disruptive when the existing frame is in good condition, but they demand more precision during fitting. The right choice depends on the state of the existing frame and the scope of the renovation.
How to Decide: Prehung or Slab for Your Project
Two questions resolve the prehung vs slab decision for most residential projects. The answers determine which option saves time, money, and installation effort in the specific situation.
Choose a Prehung Interior Door When
This door type is the right choice in three situations. First, when there is no existing frame because the opening is new construction or a wall has been modified and the original frame removed. Second, when the existing frame is damaged, warped, or out of square: a door that does not close cleanly, has visible gaps between the door edge and the stop, or requires force to latch indicates a frame that is no longer suitable for a slab replacement. Third, when the renovation already involves opening the wall for other reasons, in which case replacing the frame at the same time adds minimal extra work and ensures a fresh, factory-aligned installation from the start.
This option also makes sense when the home is being updated with a new door style across multiple rooms, since installing uniform new frames throughout produces a more consistent result than fitting new slabs into frames of varying ages and conditions.
Choose a Slab Door When
The slab option is the right choice when the existing frame is confirmed to be in good condition: level, plumb, square, and with hinge locations that match the new door panel dimensions. The simplest way to confirm this is to evaluate the current door: if it opens, closes, and latches without catching, sticking, or requiring adjustment, the frame is likely suitable for a slab replacement. If the current door has any of those issues, the frame is the source of the problem and a prehung unit is the correct solution.
The slab is also the practical choice when the existing trim and casing are in good condition and the homeowner wants to avoid the disruption of removing and reinstalling it. Prehung installation requires removing all casing on both sides of the opening, which adds time and material cost to the project. When the trim is intact and the frame is sound, a slab door achieves the same visual result with far less disruption.
See more: Door Slab vs Prehung: What's the Difference and Which One Is Right for Your Project?
What Prehung Interior Door Installation Involves
Understanding the installation process helps set realistic expectations for the project, whether you are planning to do the work yourself or budgeting for a professional installer.
Removing the Existing Frame
Installation begins with removing the existing door and frame completely. This includes all casing on both faces of the wall, the jamb legs on both sides, and the header. The rough opening is then cleared of any debris, old fasteners, or damaged framing before the new unit is introduced. This step is where the most time and disruption occurs in a prehung replacement, and it is the main reason homeowners with intact frames and functioning doors often choose a slab instead.
Setting and Shimming the Unit
The unit is placed in the rough opening and shimmed at the hinge locations, the latch side, and the header until the frame is level on the head and plumb on both jamb legs. Shims are driven from both sides of the opening to hold the unit in position without twisting the jamb out of square. The door panel is opened and closed repeatedly during shimming to confirm that the gap between the door edge and the stop is even on all three sides before any fasteners are set permanently. Once the unit is confirmed level, plumb, and square, it is fastened through the shims into the structural framing.
Finishing the Opening
After the unit is secured, casing is cut and installed on both faces of the wall to cover the gap between the jamb edge and the surrounding drywall. Casing is measured, mitered at the corners, and nailed to the jamb and the wall framing. Door hardware, including the handle set and strike plate, is installed last. Because a prehung interior door unit is significantly heavier and more awkward to maneuver than a slab, the installation is a two-person job: one person holds the unit in position while the other checks plumb and drives the first fasteners.
See more: Types of Flush Doors: Hollow Core, Solid Core, and Surface Finishes Explained
Final Thoughts
Knowing what is a prehung interior door makes the renovation decision straightforward. This door type simplifies projects by delivering the slab, frame, and hinges as one factory-aligned unit, removing the precision fitting challenges that slab installation requires. It is the right choice whenever an existing frame cannot be reused, the project involves new construction, or a consistent result across multiple openings is the goal. For openings with a solid existing frame, a slab achieves the same result with less disruption and lower material cost.
Browse interior door options at Doors and Beyond, including single swing, double swing, and French door configurations: Browse Interior French Doors at Doors and Beyond
What Is a Prehung Interior Door? Components, Sizes, and When to Choose One Over a Slab
If you are shopping for interior doors for the first time or planning a renovation, you will quickly encounter two options: prehung and slab. What is a prehung interior door, and how does it differ from a slab? Understanding the difference matters because it determines how much installation work is involved, whether an existing frame can be reused, and what additional materials you need to purchase. This guide covers both questions and explains when a prehung interior door is the right choice for your project.
A prehung interior door is a complete unit that comes with the door slab, a three-sided frame (two vertical jambs and a header), and pre-attached hinges. Most units also include pre-drilled holes for the lockset and latch. Unlike a slab door, which is just the panel, a prehung interior door is ready to install directly into a rough opening without reusing an existing frame.
What a Prehung Interior Door Includes
What are prehung interior doors made up of? This type of door is sold as a pre-assembled unit, meaning several components that would otherwise need to be sourced and fitted separately come ready to install. Knowing exactly what is included prevents surprises at the project stage and allows for accurate material budgeting before work begins.
|
Component |
What It Is |
Typically Included? |
|
Door slab |
The panel itself , the actual door surface, in hollow or solid core construction |
Yes |
|
Door jamb (frame) |
Three-sided frame: two vertical legs (jambs) plus a header across the top |
Yes |
|
Hinges |
Pre-mortised into both the door slab and jamb, factory-aligned for correct swing |
Yes |
|
Lockset bore hole |
Hole bored through the door face for the handle or knob hardware |
Yes, on most units |
|
Strike plate mortise |
Recess cut into the jamb for the latch strike plate |
Yes, on most units |
|
Stop molding |
Thin strip inside the jamb that the door panel closes against when latched |
Yes, integrated into jamb |
|
Door casing / trim |
Decorative molding covering the gap between jamb and wall on both faces of the opening |
Not always , confirm before ordering |
Every unit includes the slab, frame, and hinges. Pre-drilled hardware holes are standard on most units. The one component that is not always included is the door casing, which is the decorative trim covering the gap between the frame and the surrounding wall. Always confirm whether casing is included before ordering, and budget for it separately if it is not.
A Note on Door Casing
Casing is the decorative trim molding that covers the gap between the door jamb and the surrounding drywall on both sides of the wall. It is visible every time you walk through a doorway, which makes it an important aesthetic component. Some prehung interior door units include casing as part of the package; others ship the frame and panel only, leaving casing as a separate purchase. When ordering a prehung interior door, confirm whether casing is included in the unit description. If it is not, casing is measured and cut on-site to fit the specific wall thickness and installed after the prehung unit is set and fastened.
See more: Types of Interior Doors: Every Style, How They Work, and Which Room They Suit
Standard Prehung Interior Door Sizes
Prehung interior doors are manufactured in standard dimensions that correspond to common rough opening sizes in US residential construction. Knowing the standard sizes before measuring your opening helps confirm whether a standard unit fits or whether a custom size is required.
Standard Heights
The most common prehung interior door height in the US is 80 inches, which suits homes built with standard 8-foot ceilings. An 84-inch height is available for transitional or slightly taller ceiling heights, and a 96-inch option suits homes with 9-foot or 10-foot ceilings where standard 80-inch doors would look visually undersized relative to the wall height. When in doubt, measure the existing door opening from the subfloor to the underside of the header and confirm which height best matches the space.
Standard Widths
Single prehung interior doors are most commonly available in widths of 24, 28, 30, 32, and 36 inches. The 28-inch and 30-inch widths suit bathroom and secondary room openings. The 32-inch width is the most common for bedroom doors. The 36-inch width provides additional clearance and is often specified in master bedrooms, home offices, and accessibility-focused renovations where extra passage width is a requirement. Double prehung configurations, where two panels are mounted in a single wider frame, are available in total widths from 48 to 72 inches and suit formal dining rooms, living areas, and any opening where a wider passage or a French door aesthetic is the goal.
Rough Opening and Clearance
The rough opening must be sized to accommodate the prehung unit plus a clearance allowance for shimming. As a general rule, the rough opening should be approximately 2 inches wider and 2 inches taller than the door unit dimensions to provide room for adjustment. A 32-inch prehung interior door, for example, requires a rough opening of approximately 34 inches wide. Always confirm the specific clearance requirement with the manufacturer or supplier, as tolerances vary by product and frame thickness.
See more: Best Way to Paint Interior Doors: Tools, Prep, and Technique for a Pro Finish
Prehung vs Slab Interior Doors: Side-by-Side Comparison
The choice between a prehung and a slab interior door is the most important decision in any door replacement or renovation project. The two options look identical once installed, but the installation process, cost, and project requirements are significantly different.
|
Criteria |
Prehung Interior Door |
|
|
What is included |
Door slab, frame (jamb), hinges, pre-drilled hardware holes |
Door panel only |
|
Frame requirement |
Installs in rough opening; no existing frame needed |
Requires existing frame that is level, plumb, and square |
|
Installation complexity |
Moderate: shim and level the full unit in the rough opening; two-person job |
Higher precision: hinge mortises, lock holes, and fit must align exactly with existing frame |
|
Best used when |
New construction; damaged or out-of-square existing frame; full renovation |
Existing frame is in good condition; trim and casing to be preserved |
|
Relative cost |
Higher , frame is included in the purchase price |
Lower , panel only; existing frame is reused |
|
Installation time (approx) |
1 to 3 hours per door with a helper |
2 to 4 hours per door; more precision carpentry required |
|
Disruption to existing trim |
High , all casing on both sides must be removed and reinstalled |
Low , existing casing can often be preserved |
Prehung interior doors are the more complete and installation-ready option, but they require removing and replacing the entire door frame, which involves reinstalling all casing. Slab doors are more economical and less disruptive when the existing frame is in good condition, but they demand more precision during fitting. The right choice depends on the state of the existing frame and the scope of the renovation.
How to Decide: Prehung or Slab for Your Project
Two questions resolve the prehung vs slab decision for most residential projects. The answers determine which option saves time, money, and installation effort in the specific situation.
Choose a Prehung Interior Door When
This door type is the right choice in three situations. First, when there is no existing frame because the opening is new construction or a wall has been modified and the original frame removed. Second, when the existing frame is damaged, warped, or out of square: a door that does not close cleanly, has visible gaps between the door edge and the stop, or requires force to latch indicates a frame that is no longer suitable for a slab replacement. Third, when the renovation already involves opening the wall for other reasons, in which case replacing the frame at the same time adds minimal extra work and ensures a fresh, factory-aligned installation from the start.
This option also makes sense when the home is being updated with a new door style across multiple rooms, since installing uniform new frames throughout produces a more consistent result than fitting new slabs into frames of varying ages and conditions.
Choose a Slab Door When
The slab option is the right choice when the existing frame is confirmed to be in good condition: level, plumb, square, and with hinge locations that match the new door panel dimensions. The simplest way to confirm this is to evaluate the current door: if it opens, closes, and latches without catching, sticking, or requiring adjustment, the frame is likely suitable for a slab replacement. If the current door has any of those issues, the frame is the source of the problem and a prehung unit is the correct solution.
The slab is also the practical choice when the existing trim and casing are in good condition and the homeowner wants to avoid the disruption of removing and reinstalling it. Prehung installation requires removing all casing on both sides of the opening, which adds time and material cost to the project. When the trim is intact and the frame is sound, a slab door achieves the same visual result with far less disruption.
See more: Door Slab vs Prehung: What's the Difference and Which One Is Right for Your Project?
What Prehung Interior Door Installation Involves
Understanding the installation process helps set realistic expectations for the project, whether you are planning to do the work yourself or budgeting for a professional installer.
Removing the Existing Frame
Installation begins with removing the existing door and frame completely. This includes all casing on both faces of the wall, the jamb legs on both sides, and the header. The rough opening is then cleared of any debris, old fasteners, or damaged framing before the new unit is introduced. This step is where the most time and disruption occurs in a prehung replacement, and it is the main reason homeowners with intact frames and functioning doors often choose a slab instead.
Setting and Shimming the Unit
The unit is placed in the rough opening and shimmed at the hinge locations, the latch side, and the header until the frame is level on the head and plumb on both jamb legs. Shims are driven from both sides of the opening to hold the unit in position without twisting the jamb out of square. The door panel is opened and closed repeatedly during shimming to confirm that the gap between the door edge and the stop is even on all three sides before any fasteners are set permanently. Once the unit is confirmed level, plumb, and square, it is fastened through the shims into the structural framing.
Finishing the Opening
After the unit is secured, casing is cut and installed on both faces of the wall to cover the gap between the jamb edge and the surrounding drywall. Casing is measured, mitered at the corners, and nailed to the jamb and the wall framing. Door hardware, including the handle set and strike plate, is installed last. Because a prehung interior door unit is significantly heavier and more awkward to maneuver than a slab, the installation is a two-person job: one person holds the unit in position while the other checks plumb and drives the first fasteners.
See more: Types of Flush Doors: Hollow Core, Solid Core, and Surface Finishes Explained
Final Thoughts
Knowing what is a prehung interior door makes the renovation decision straightforward. This door type simplifies projects by delivering the slab, frame, and hinges as one factory-aligned unit, removing the precision fitting challenges that slab installation requires. It is the right choice whenever an existing frame cannot be reused, the project involves new construction, or a consistent result across multiple openings is the goal. For openings with a solid existing frame, a slab achieves the same result with less disruption and lower material cost.
Browse interior door options at Doors and Beyond, including single swing, double swing, and French door configurations: Browse Interior French Doors at Doors and Beyond
