If you’ve ever shopped for a door and felt strangely overwhelmed by what seems like a simple purchase, you’re not alone. Doors sit at the intersection of design, security, insulation, accessibility, and day-to-day convenience. And before you even pick a style, you’ll run into a big decision: prehung or slab?
Knowing the difference can save you time, money, and a whole lot of installation frustration. It can also help you avoid common issues like a door that rubs, won’t latch, leaks air, or looks slightly “off” even when it technically fits. This guide breaks down what prehung and slab doors really are, how they’re installed, what they cost, and when each option makes the most sense—whether you’re renovating an older home, building new, updating a rental, or replacing a single damaged door.
What you’re actually buying when you buy a door
When someone says “I need a new door,” they might mean very different things. Sometimes they need only the door panel. Other times they need the frame, hinges, weatherstripping, and threshold too. The prehung vs slab question is really about how many components you’re replacing at once.
Before we define each type, it helps to think about your existing opening as a system: the rough opening in the wall, the door frame (jambs), the trim/casing, the hinges, the latch/strike, and the door itself. If any of those parts are out of square, water-damaged, or poorly aligned, it affects which choice is smarter.
Prehung doors: the “ready-to-install” package
A prehung door comes already mounted on hinges inside a new frame (jamb). It’s essentially a complete unit that gets set into the rough opening. Many prehung exterior units also include weatherstripping, a threshold, and sometimes brickmould for the exterior side.
This is why prehung doors are popular for new construction and major renovations: you’re installing a full assembly that’s designed to work together. The hinge locations are pre-mortised, the door is already aligned to the frame, and the manufacturer has done much of the fussy fitting work that can be hard to replicate on-site.
What usually comes with a prehung door
Exact contents vary, but a typical prehung unit includes the door slab, side jambs, head jamb, and hinges already attached. Exterior versions often add a sill/threshold and integrated weather seals. Some packages also include pre-drilled holes for the lockset and deadbolt.
That “system” approach matters. When the slab, frame, and seals are designed together, you’re more likely to get consistent gaps around the door and better performance against drafts and moisture—especially important in Canadian climates where freeze-thaw cycles can be tough on entryways.
Another underrated benefit: prehung doors make it easier to correct problems in the existing opening. If your old frame is warped or out of square, swapping the whole unit gives you a fresh start.
Why prehung doors are often easier (even if they look bigger)
Prehung doors can feel like a bigger commitment because you’re replacing more material. But from an installation standpoint, they’re often more straightforward for pros and confident DIYers. You set the unit, shim it plumb and level, fasten it, and then add trim.
With a slab-only replacement, all the precision work happens in the field: hinge mortises, alignment, latch positioning, and sometimes trimming. That’s doable, but it’s less forgiving. Prehung doors shift the precision work to the factory.
One more practical point: if you’re replacing an exterior door and you want modern weatherstripping and a solid threshold, prehung is often the most efficient way to get there without trying to retrofit seals onto an older frame.
Slab doors: the door panel only
A slab door is just the door itself—no frame, no hinges attached, no weatherstripping. It might be completely blank (no hinge mortises or lock holes), or it might be “prepped” (machined for hinges and hardware) depending on where you buy it and how you order it.
Slab doors are a great option when your existing frame is in good shape and you’re happy with its layout. They’re also common for interior doors, where weather sealing isn’t a factor and swapping the panel is often all you need to refresh a room.
When a slab door is a perfect fit
If your current jamb is solid, square, and not rotted or split, a slab replacement can be the simplest path. You keep your existing trim, your existing frame, and just replace the panel. This can be especially appealing in older homes with detailed casing you don’t want to disturb.
A slab makes sense when the door is damaged (cracked, delaminated, or dented) but the frame is still doing its job. It also works well when you’re trying to match other doors in the house and the frame sizes are non-standard—because you can order or trim a slab to suit.
Finally, slabs are handy when you need a custom look—like a unique panel design, glass pattern, or wood species—while keeping the original jambs intact.
The tradeoff: slabs demand more measuring and carpentry
Slab installation is less “plug-and-play.” You’ll need to confirm the slab thickness, hinge size, hinge placement, swing direction, and the exact height/width you need. If the slab isn’t prepped, you’ll also need to mortise hinges and drill for the latch and deadbolt.
Even if the slab is prepped, it has to match your existing frame’s hinge layout and backset. If it doesn’t, you’ll be filling old mortises, cutting new ones, or adjusting hardware—small tasks that can turn into a long afternoon.
And with exterior doors, the stakes are higher. A tiny misalignment can create an air leak, a sticky latch, or a door that doesn’t compress weatherstripping evenly.
How to tell what you have right now (and what shape it’s in)
Before you decide, take a close look at your existing door and frame. Many “door problems” are actually frame problems: settling, moisture damage, loose hinges, or a jamb that’s no longer square.
Start by opening the door halfway and letting go. If it swings open or closed on its own, the frame may be out of plumb. Look at the reveal (the gap between the door and the frame). If the gap is uneven—tight at the top, wide at the bottom—it’s a clue that a simple slab swap might not solve your issue.
Quick checks that point toward prehung
If you see soft wood, dark staining, or crumbling near the exterior threshold or lower corners of the frame, you’re likely dealing with moisture damage. In that case, replacing only the slab may leave the real problem untouched.
Also watch for a frame that’s visibly twisted or cracked, or a door that has been planed down repeatedly over the years. Those are signs the opening has shifted and the old jamb has been “chased” with fixes. A prehung unit lets you reset everything properly with shims and fasteners.
If you’re upgrading for energy efficiency—better seals, less draft, improved comfort—prehung exterior doors typically deliver more consistent results because the frame and sealing system are designed as one.
Quick checks that point toward slab
If the frame is solid, the door closes smoothly, and the latch lines up nicely, you may not need to disturb the jamb at all. This is common with interior doors and with exterior doors that have been well-maintained and protected by a porch overhang.
Another good sign: the existing hinges are tight, the jamb isn’t split around the strike plate, and the casing looks clean with no signs of water intrusion. In that situation, a slab can be a cost-effective refresh—especially if you’re changing the style from flat to panelled, or from solid to glass-insert.
Slab replacements are also popular when you want to keep original trim details. Removing a prehung unit can mean redoing casing, paint, and sometimes drywall touch-ups.
Installation realities: what the job looks like in the real world
On paper, prehung sounds bigger and slab sounds simpler. In practice, the “easier” choice depends on your opening, your tools, and your tolerance for fine-tuning.
It also depends on whether you’re doing an interior or exterior door. Exterior doors bring extra layers: weatherproofing, thresholds, security, and sometimes code considerations around egress or accessibility.
What installing a prehung door typically involves
Installing a prehung unit usually means removing the existing door and frame down to the rough opening. Then you dry-fit the new unit, shim the hinge side plumb, level the head, and adjust the latch side so the reveal is even. Once it’s square and operating smoothly, you fasten it, insulate the gaps, and reinstall or replace trim.
For exterior doors, you’ll also deal with flashing, sill pan or membrane, and sealing to keep water out. This is where careful work pays off. A well-installed prehung door feels solid, closes cleanly, and stays that way through seasonal movement.
If you’re hiring a contractor, prehung installations are very common and usually easier to quote because the process is standardized.
What installing a slab door typically involves
With a slab, you’re fitting the door to an existing frame. That means measuring the old slab precisely (height, width, thickness), confirming hinge size and placement, and checking whether the new slab needs trimming. If you’re reusing hinges, the mortises need to match perfectly.
Then there’s hardware. The latch bore (the big hole for the knob/lever) and the edge bore (for the latch) must line up with your strike plate. If you’re changing hardware style or backset, you may need to move the strike plate too.
Slab installs can be very satisfying when everything lines up. But if the frame is slightly out of square, you might need to scribe and plane the slab, adjust hinges, or tweak the stop moulding to get a good seal and smooth swing.
Cost and value: where the money actually goes
Slab doors often cost less upfront because you’re buying fewer parts. But the full cost depends on prep work, tools, and labor. A slab that requires mortising, drilling, trimming, and multiple adjustments can quickly eat up the savings.
Prehung doors typically cost more as a product, but can reduce installation time and reduce the chance of performance issues—especially for exterior applications where sealing and alignment matter.
Product cost vs install cost
If you’re DIY-ing and you already have tools like a router (for hinge mortises), a good plane, and hole saws, slab work can be affordable. If you need to buy specialty tools or jigs, the price gap narrows.
For hired labor, prehung installations can be more predictable. Slab installs can be quick when it’s a direct match, but can also take longer if the frame is quirky or if the new slab needs custom fitting.
A helpful way to think about it: with slabs, you’re paying in time and precision. With prehung units, you’re paying for factory alignment and a full system.
Long-term value: comfort, durability, and fewer headaches
For exterior doors, long-term value often favors prehung because you’re getting new seals, a fresh threshold, and a frame that hasn’t been compromised by years of moisture and movement. That can translate into fewer drafts, less water intrusion risk, and smoother operation over time.
For interior doors, value is often about aesthetics and function. If the frame is fine, a slab swap can refresh a space without the mess of trim work and repainting.
And if you’re choosing higher-end materials or custom designs, the “value” can also be how the door feels every day—solid, quiet, and well-fitted rather than hollow or rattly.
Interior doors: choosing based on style, sound, and daily use
Interior doors are where slab replacements really shine. You can update the look of a home—modern flush, classic shaker, glass panel, or solid core—without tearing out frames and casing.
But interior doors still have practical considerations: privacy, noise control, and durability in high-traffic areas like kids’ rooms, laundry rooms, and home offices.
When interior prehung doors make sense
If you’re doing a major remodel and walls are open, prehung interior doors can speed up the process and make everything consistent. You get matching jambs, consistent reveals, and less fiddling with old frames that may have shifted over decades.
Prehung interior units are also helpful when you’re changing the layout—moving a doorway, widening an opening, or correcting a badly installed frame. In those cases, you’re essentially resetting the opening, so a prehung unit is the natural choice.
And if you want to upgrade from hollow core to solid core for better sound control, prehung can ensure the heavier door is properly supported with the right hinges and frame fit.
When interior slab doors are the easy win
If your goal is mostly visual—replacing dated panel profiles or mismatched doors—slabs can be a clean upgrade. You keep your trim intact, which matters in homes with character mouldings or older plaster walls where trim removal can cause damage.
Slabs are also convenient if you’re replacing one door at a time. Maybe a door got damaged, or you’re slowly updating finishes room by room. A slab lets you do targeted improvements without turning the project into a whole-house disruption.
Just remember to match thickness and hinge layout. Interior doors can vary (especially in older homes), so measure carefully before ordering.
Exterior doors: where performance details matter most
Exterior doors do more than look nice. They deal with wind, rain, sun, temperature swings, and security concerns. That’s why the prehung vs slab decision for exterior openings often leans toward prehung—especially if you’re noticing drafts, sticking, or water issues.
That said, slab exterior replacements can still work well in the right scenario, particularly when the existing frame is high quality and properly flashed.
Prehung exterior doors for weather, security, and peace of mind
If you’re replacing an exterior door because it’s drafty, swollen, or hard to lock, there’s a good chance the frame and seals are part of the problem. A prehung unit replaces those weak points and gives you a fresh sealing surface all around.
Prehung exterior doors also simplify upgrades like better thresholds, multi-point locks, and improved weatherstripping. When everything is designed to fit together, you reduce the chance of tiny gaps that become big comfort issues in winter.
If you’re shopping for higher-performance options—fiberglass, steel, insulated cores, or decorative glass—many of the best options are sold as complete prehung systems for a reason.
When an exterior slab replacement can still be smart
If your existing exterior frame is solid hardwood or a well-built composite jamb that’s still square and sealed, replacing only the slab can be a practical way to update the look without disturbing exterior trim, siding, or brickmould.
This can be especially useful if the exterior casing is integrated with stucco, stone, or other finishes that are difficult to remove cleanly. In those cases, keeping the frame can avoid a cascade of repairs.
Just be honest about the condition of the sill and lower jamb corners. Those areas take the most abuse and are the first to fail. If there’s any doubt, prehung is usually the safer bet.
If you’re browsing styles and configurations, it can help to look at curated selections of exterior residential doors to get a feel for materials, glass options, and panel designs that work for different home styles and climates.
Renovation scenarios: which type fits your project?
Let’s make this practical. Most people aren’t replacing doors in a vacuum—they’re dealing with a specific situation: a dated entry, a damaged panel, a remodel, or a tricky old-house opening.
Here are the most common scenarios and which direction they typically point.
You’re replacing a door in an older home with settled framing
Older homes often have charm—and openings that aren’t perfectly square. If the existing frame has been “made to work” over decades, a slab replacement can be tricky because the new door may need custom trimming and careful hinge adjustment.
If the jamb is still strong and you want to preserve original trim, a slab can be worth it. But if you’re already seeing uneven gaps, sticking, or latch alignment issues, a prehung unit gives you a chance to re-square the opening and start fresh.
In many older homes, the best answer is: inspect first, decide second. The frame condition matters more than the age of the house.
You’re doing a full remodel (new floors, new trim, new paint)
If you’re already replacing baseboards and casing, prehung doors can be a smooth choice because you’re not trying to protect existing trim. You can set new frames, match all the reveals, and create a consistent look across the whole level.
Prehung units also help when new flooring changes finished floor height. If you’re adding thicker flooring, you may need to re-evaluate door clearances and thresholds. A prehung install is a good time to handle those details cleanly.
For remodels where timing matters (for example, you want doors installed before painters arrive), prehung doors can keep the schedule predictable.
You need a single replacement fast
If one interior door is damaged and you want the simplest fix, a slab can be the quickest—assuming you can match size and hinge layout. You can often swap it without touching trim or repainting the frame.
For an exterior door, “fast” can be risky if you rush the sealing details. If the frame is questionable, prehung is often the better long-term fix even if it’s a bigger day-one project.
Either way, prioritize correct measurements over speed. A door that almost fits tends to become a repeating problem.
Measuring without regret: the details that trip people up
Measuring for doors sounds straightforward until you realize how many “sizes” are involved: slab size, frame size, rough opening size, and sometimes nominal vs actual dimensions. Getting clear on what you’re measuring prevents ordering mistakes.
When in doubt, measure the existing door and the opening, and take photos of hinges, latch edge, and the frame profile. If you’re working with a supplier, those details help them guide you to the right option.
Measuring for a slab door
Start with the existing slab: measure width, height, and thickness. Then confirm the hinge locations: measure from the top of the door to the top of each hinge, and note hinge size. Check the swing (left-hand vs right-hand) by standing on the side where you pull the door toward you.
Next, confirm hardware prep: the backset (distance from the door edge to the center of the knob hole) is commonly 2-3/8″ or 2-3/4″. If you’re reusing the existing lockset, match the backset to avoid extra drilling or patching.
Finally, check clearance. If the old door was shaved down to stop rubbing, a new slab may need similar trimming—or you may need to address the underlying frame issue.
Measuring for a prehung door
For prehung units, you’ll usually measure the rough opening (framing opening) and the wall thickness (to select the right jamb depth). Rough openings are typically larger than the door size to allow for shimming.
You’ll also want to think about exterior details: is there a porch roof? Which way does the door swing? Do you need a sill height that works for kids, seniors, or accessibility needs? These decisions affect comfort and usability every day.
If you’re replacing an existing prehung exterior door, you can also measure the existing frame size (jamb-to-jamb). But rough opening measurements are still valuable if you suspect framing changes or water damage repairs.
Design and customization: making the door match the building (not just the opening)
Doors are one of the most noticeable design elements on a home or building. The style you choose can make an entry feel welcoming, modern, traditional, or bold. And beyond looks, customization can solve practical needs like privacy, light control, and durability.
This is where working with the right supplier matters. A door isn’t just a commodity—especially when you need specific glass, wood species, paint-grade vs stain-grade, or a unique size.
Why customization changes the prehung vs slab conversation
If you’re ordering a truly custom size or style, you’ll often get better results by treating the door as a system. A prehung custom unit ensures the slab and frame are built to match, which can reduce on-site modifications and help the door operate smoothly.
But customization doesn’t automatically mean “prehung only.” If you have a beautiful existing frame (for example, in a heritage home) and you want a new panel that matches the original character, a custom slab can be the perfect compromise.
Either way, you’ll want to communicate clearly about swing direction, hinge prep, hardware prep, and finish requirements.
Choosing the right partner for specialty doors
When you’re aiming for a standout entry or dealing with non-standard requirements, it helps to work with a supplier that’s comfortable building to spec. Many homeowners and builders look for a custom door manufacturer when they want more control over materials, proportions, glass options, and overall fit—especially for projects where the door is a focal point rather than an afterthought.
It’s also helpful because specialty doors often come with extra considerations: heavier weight, reinforced framing, unique hardware, or specific finishing steps. Having those details handled correctly at the manufacturing stage can make installation smoother.
If you’re comparing quotes, don’t just compare the door price—compare what’s included (frame, seals, threshold, prep work) and what you’ll need to add on-site.
Special-use buildings and unique entries: not all doors are “residential standard”
Some entries have requirements that go beyond the typical house door. Think of buildings with higher traffic, larger openings, or a need for a specific aesthetic that matches the architecture. In these cases, the prehung vs slab decision often comes down to durability, fit, and how much of the surrounding structure you can realistically change.
Places like churches, community buildings, and older institutional spaces may have tall doors, paired doors, arched tops, or unique trim conditions. Those details can push you toward custom solutions.
High-traffic entries and long-term durability
When a door is opened hundreds of times a week, alignment and hardware support matter. A well-built frame, properly anchored, helps prevent sagging and latch issues over time. That’s one reason prehung systems are common in higher-use settings: the frame and slab are designed to work together from day one.
That said, some buildings have frames that are part of the architecture—stone surrounds, heavy timber, or ornate interior trim that’s not easily replaced. In those cases, a slab replacement might be chosen to preserve the original structure while refreshing the door panel itself.
If you’re dealing with a unique building type, it’s worth looking at examples of purpose-built church front doors to see how design, scale, and durability are handled in real projects.
Sound, privacy, and the “feel” of the entry
In special-use buildings, the door experience matters. A hollow, lightweight door can feel out of place in a grand entry. A heavier slab with the right core and a well-fitted frame can create that satisfying, solid close that signals quality.
Sound control can also be a bigger deal than people expect. In spaces used for gatherings, services, or events, a door that seals well can help manage noise between vestibules and main rooms.
If the entry is meant to be welcoming, glass choices matter too. You can bring in light while still maintaining privacy through textured or decorative glazing.
Common mistakes (and how to avoid them)
Most door regrets come from one of two things: ordering the wrong configuration, or underestimating the importance of the frame. A door is only as good as the opening it’s installed into.
Here are the mistakes that show up again and again, plus what to do instead.
Mistake: assuming your opening is standard
Even in newer homes, “standard” isn’t guaranteed. Small variations happen, and older homes can be all over the map. Measure carefully and verify what you’re measuring: slab size, frame size, and rough opening are not the same.
If you’re ordering a slab, confirm hinge placement and backset. If you’re ordering prehung, confirm swing direction and jamb depth. A few minutes of measurement can prevent days of frustration.
When possible, bring the old slab measurements and photos to your supplier. Visual details help catch issues early.
Mistake: replacing only the slab when the frame is the real problem
If the door sticks, won’t latch, or has uneven gaps, the frame may be out of square or moving with the seasons. A new slab might temporarily “work,” but you’re still fighting the same geometry.
For exterior doors, this can also mean ongoing drafts or water intrusion. If the jamb corners are soft or the threshold is worn, it’s usually time for a full prehung replacement.
When in doubt, inspect the lower corners and the sill area closely. That’s where hidden damage often lives.
Mistake: forgetting about finishing and maintenance
Doors aren’t just installed—they’re finished and maintained. If you’re choosing wood, think about exposure to sun and rain. A beautiful wood door can last a long time, but it needs the right finish and periodic upkeep.
Fiberglass and steel can be lower maintenance, but still require proper sealing and paint where needed. And regardless of material, a well-installed threshold and weatherstripping will do more for comfort than almost anything else.
It’s also worth thinking about how the door will age. High-traffic entries benefit from durable finishes and quality hardware that won’t loosen quickly.
A simple decision framework you can actually use
If you’re still on the fence, here’s a practical way to decide without overthinking it. Ask yourself three questions: Is the frame in great shape? Do you need better sealing/performance? Are you trying to preserve existing trim or architectural details?
Your answers will usually point clearly toward slab or prehung.
Choose prehung when…
You’re replacing an exterior door for comfort, energy performance, or security upgrades. You suspect the frame is out of square, water-damaged, or patched repeatedly. You’re doing a remodel where trim is already coming off, or you want everything to look consistent and new.
Prehung is also a strong choice when you’re ordering a higher-end or custom configuration and you want the factory to handle alignment, sealing surfaces, and hinge placement as a complete system.
If you want fewer surprises during installation, prehung is often the safer bet.
Choose slab when…
Your existing frame is solid, square, and you like the trim. You’re updating interior doors for style, sound, or function without wanting to repaint or redo casing. Or you have a unique frame you want to preserve (common in older homes and specialty buildings).
Slabs can also be ideal for targeted replacements—one door at a time—when you can match size and prep details accurately.
Just go into it knowing that slab installs reward careful measurement and patience.
Final thoughts to keep your project smooth
Picking between prehung and slab doors isn’t about which one is “better.” It’s about what you’re trying to fix, what you’re trying to preserve, and how much of the existing opening you trust. When the frame is questionable or performance matters (especially outside), prehung is often the cleanest long-term solution. When the frame is great and you want a simpler aesthetic upgrade (especially inside), slab can be the smart, efficient move.
If you take one thing from this guide, let it be this: spend extra time evaluating the frame and measuring properly. Doors are one of those home upgrades where small details—an eighth of an inch here, a slightly twisted jamb there—make a huge difference in how the finished result feels every single day.