On a new build, interior doors are the moment the framing turns into finished rooms — and the moment a trim crew either flies or fights the whole house. The difference is almost never skill. It is whether the openings were framed to the door spec, whether the units arrived pre-hung and pre-bored to that spec, and whether the crew runs a consistent set-and-shim sequence. Here is the spec and the order of operations that keeps interior door installation on schedule.
Start with the rough opening — the spec that decides everything
Most door trouble is framed in before a single unit arrives. If the openings are not sized to the doors, no amount of shimming saves the schedule. Frame to this:
- Width — rough opening = door slab width + 2 inches. A 30-inch door gets a 32-inch opening.
- Height — door height + about 2 to 2.5 inches from the finished subfloor. A standard 80-inch (6‘8”) door wants roughly 82.5 inches.
- Plumb trimmers and a level header — the opening should be square before the door shows up, so the jamb only has to correct small variation, not a racked opening.
Standard interior slab sizes:
| Common use | Slab width | Height |
|---|---|---|
| Closet / pantry | 18”, 20”, 22”, 24” | 80” |
| Secondary rooms | 28”, 30” | 80” |
| Primary / accessible | 32”, 36” | 80” |
| Tall-door plans | 30”, 32”, 36” | 96” (8‘0”) |
Eight-foot doors and non-standard widths are order items, not stock pulls — get them on the schedule early so they are pre-hung and on the truck when the trim crew arrives.
Match the jamb to the wall
The jamb width has to match the wall assembly or the casing will not sit flush:
- 4-9/16” — standard 2×4 wall with 1/2” drywall both sides.
- 6-9/16” — 2×6 wall.
- Custom width — thicker walls, double drywall, or plaster.
Order the jamb to the wall you are actually building and you skip jamb extensions and the labor that comes with them.
Get the hardware bore right before the door ships
Pre-bored doors save the finish carpenter real time, but only if the bore matches the hardware schedule. The standard interior spec:
- Cross bore — 2-1/8” diameter for the lockset.
- Edge bore — 1” diameter for the latch.
- Backset — 2-3/8” standard (2-3/4” on some plans). This is the distance from the door edge to the center of the bore.
Confirm the backset against the actual hardware before anything is bored. A door bored to the wrong backset is a callback, not a quick fix.
The set-and-shim sequence
Setting a pre-hung interior door is a repeatable five-step move. Run it the same way every time and the reveals stay even down the hall:
- Confirm the opening against the slab — 2 inches wider, ~2.5 inches taller, trimmers plumb.
- Set the unit and shim the hinge jamb plumb first. The hinge side carries the load — get it dead plumb before fastening anything.
- Set a consistent 1/8-inch reveal across the top and the latch side. The reveal is your proof the unit is square; if it tapers, re-shim.
- Fasten through the jamb into the trimmers at each shim, and behind the hinges on solid-core doors so the weight is carried into framing.
- Swing the door and confirm it holds anywhere in its arc — no drifting open or closed — before you case it.
A door that drifts is a door that is not plumb. Fix it before the casing goes on, not after.
Handing — get the swing right at the order
Handing is which way the door swings and where the hinges land. Face the door so it swings away from you: hinges on the left means left-handed, hinges on the right means right-handed. Specifying handing correctly at the order keeps the swing right for the room — doors that clear into the space, against a wall, away from a light switch — and keeps the hardware mortised on the correct edge. It is a 10-second decision at the order that is a torn-out jamb if it is wrong.
How Abel Door & Trim keeps the install fast
Abel Door & Trim pre-hangs to your spec, not to a generic stock configuration. We match the jamb width to your wall, bore to your hardware backset, mortise the hinges, and mark the handing — so the units land at the jobsite ready to set, not ready to rework. For a volume build, that consistency is what lets a trim crew set a house in a day instead of fighting mismatched jambs and wrong bores.
The big-box pre-hung looks like the same product until you find the jamb is wrong for your wall and the bore is wrong for your hardware. We take off the doors from your plans, pre-hang to your build, and deliver on your schedule with photo confirmation — so you know the right doors, bored the right way, are on the truck before it leaves the yard. That is the verification framework behind every order: plan and spec in, pre-hang to spec, install clean, finish confirmed.
Get your interior doors taken off and pre-hung
Send us your plans and door schedule and we will run the takeoff, match jambs to your walls, bore to your hardware, mark the handing, and deliver pre-hung on your build schedule with photo confirmation. Request a takeoff or quote. For more, see our guide to pre-hung vs. slab doors, stain-grade vs. paint-grade trim for the casing package, and our products page for the manufacturers we stock.
Frequently asked questions
What size rough opening do I need for an interior door?
Frame the rough opening 2 inches wider than the door slab and about 2 to 2.5 inches taller, measured from the subfloor. A 30-inch door needs a 32-inch opening; a standard 80-inch door needs roughly 82.5 inches of height. That margin is what you shim into to set the unit plumb and square.
What is the correct reveal on an interior door?
Aim for a consistent 1/8-inch reveal — the gap between the door slab and the jamb — across the top and the latch side. An even reveal is the visual proof the unit is hung plumb and square. If the reveal tapers, the jamb is out and needs to be re-shimmed before you case it.
Which side of a pre-hung door do you shim first?
Shim the hinge jamb plumb first. The hinge side carries the weight of the door, so getting it dead plumb before fastening sets the whole unit. Once the hinge jamb is fixed and plumb, you set the reveal on the latch side and shim to match.
What are the standard hardware bore dimensions for interior doors?
Standard interior doors use a 2-1/8-inch cross bore for the lockset, a 1-inch edge bore for the latch, and a 2-3/8-inch backset — the distance from the door edge to the center of the bore. Some doors use a 2-3/4-inch backset, so confirm the hardware spec before boring.
How many hinges does an interior door need?
A lightweight hollow-core door can hang on two hinges, but most interior doors — and all solid-core doors — should use three hinges to carry the weight and keep the slab from sagging over time. Pre-hung units arrive with the hinges set and mortised at the mill.
What does door handing mean and why does it matter?
Handing describes which way the door swings and which side the hinges are on. Stand in the opening facing the door as it swings away from you — if the hinges are on the left it is left-handed, on the right it is right-handed. Getting handing right at the order keeps the swing correct for the room and the hardware.