Prehung vs. Slab Doors:
Which Should You Buy?

The short version: buy a prehung unit for any new or rebuilt opening, and a slab only when the jamb you have is worth keeping. Here is why, with numbers.

A prehung door is a complete opening delivered as one assembly: the door slab already hung on its hinges inside a finished jamb, with the stop applied and the casing bundled or attached. It drops into a framed rough opening, gets shimmed plumb and square, and is ready for trim. At G Millwork every stocked interior unit ships this way — 1-3/8" primed slab, 4-5/8" finger-jointed jamb, three hinges and WM473 colonial casing for both sides.

A slab door (also called a blank) is just the door. No jamb, no hinges, no stop, no casing. The carpenter has to mortise the hinges, bore for the lockset, build or reuse a jamb and hang it all by hand.

	Prehung unit	Slab only
What you get	Slab + jamb + hinges + stop + casing	Door slab only
Install time (per opening)	20–40 minutes for a trim carpenter	1.5–3 hours incl. hinge mortising and jamb
Best for	New construction, additions, gut remodels, any new opening	Replacing a slab in a jamb that is still square
Skill needed	Shim, level, nail	Router, hinge jig, lock bore jig, patience
Typical cost	Higher up front, lower installed	Lower up front, higher installed
Match across a job	Identical every time	Depends on the carpenter and the old jamb

Buy a slab when the existing jamb is straight, square and staying. A 1990s hollow-core door in a good jamb can be swapped for a solid-core slab in an afternoon if the new slab is bored and mortised to match. We will bore and mortise slabs to your measurements so they land ready to hang.

• Replacing one damaged door in a house that is otherwise fine.
• Historic jambs or custom casing you want to keep.
• Upgrading hollow core to solid core in bedrooms and baths.
• Bifold and bypass closet slabs on existing track.

Every new opening, and most remodels where walls are opening up. If the jamb is out of square, chewed by previous hardware, or the wall thickness changed, a new prehung unit saves the labor of fighting the old frame — and the finished opening looks the way the owner expects. On a 20-door house the labor difference alone usually pays for the jambs.

Wall thickness matters: our stocked 4-5/8" jamb fits a 2×4 wall with 1/2" drywall both sides. Tell the desk if you have 2×6 walls, furring, or plaster, and we will quote a 6-9/16" or custom-width jamb.

Style, width, core, handing and how many. The quote builder walks through those in order; if you have a door schedule from the architect, send the PDF and we will do the takeoff.