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Replacing an Interior Door: Slab vs Prehung, Hinges, Bore

Updated 2026-10-31 · Sources verified 2026-07-20

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Slab or prehung is the first decision. A slab is just the door: you reuse the jamb and hinges, so the old door is your template, and JELD-WEN limits trimming to 'a maximum of 1/4 in ... Permit in Orange County: no permit needed. Exempt finish work under FBC 105.2 and Orange County's published list — but exempt work must still comply with the Florida Building Code. The full rule and its official source are below, with the code requirements and mistakes that trip up Orlando homeowners.

Key facts before you start

Slab or prehung is the first decision. A slab is just the door: you reuse the jamb and hinges, so the old door is your template, and JELD-WEN limits trimming to 'a maximum of 1/4 in ... from each side of hollow or solid core molded and flush doors only' (Masonite's sheet is stricter: 'Do not remove any more than 1/8 in off any one side'). A prehung unit replaces the jamb too and needs the casing off and a rough opening that is 'level and plumb ... The maximum allowable deviation is 1/8 in' and square within 1/4 in. Reuse the jamb when it is straight and the casing is worth keeping; go prehung when the jamb is cracked, the old door was planed to fit a crooked frame, or you are changing the size.
Measure the old door, not the opening: width, height ('The standard height for interior doors is 6 feet 8 inches'), thickness (interior slabs are 1-3/8 in; Schlage's prep sheet says a lock 'will not fit properly' on a door thinner than 1-3/8 or thicker than 1-3/4), hinge count and spacing, the lock bore and its backset ('2-3/4 in or 2-3/8 in to match other doors on site'). Handing: 'face the door from the side where hinges cannot be seen. Right handed doors open to the right, while left handed doors open to the left' (JELD-WEN). A prehung frame should be '1/2 in smaller than the rough opening width/height'.
Let it acclimate and keep it flat: 'Allow doors to acclimate for at least 24 hours to local conditions before installation or finishing', stored 'off of the floor' at 30-50% relative humidity. Masonite: 'Do not store or install your door in a damp, or freshly dry-walled building. Keep the door at least 10 feet away from heating registers, and away from direct sunlight.' In an Orlando house that means inside with the AC running, not in the garage.
Slab swap, hinges: 'Position the hinges on your door using the existing door as your template for hinge location. Mark the mortise areas with a utility knife, or butt hinge marking tool. The barrel of each hinge should extend at least 1/8 in outside the surface of the door', then 'Chisel mortises ... to a depth that will allow hinges to lie flush'. Two hinges on a hollow-core, three on a solid-core, four on a door 84 in or taller. Starting from scratch on a jamb: top of the top hinge 7 in down from the head jamb, bottom of the bottom hinge 10 in up from the slab bottom, and the slab's hinge marks '1/8 in smaller than the distance from the head jamb to the top of the top hinge. This will allow 1/8 in gap between the slab and head jamb.'
Slab swap, hanging: 'install door by slipping top hinges together and inserting pin part way. Do not set pins all the way until the job is finished', then the lower hinges. 'If the door does not fit opening, plane door edges using old door as a template', keeping the latch edge's '2 or 3 degree bevel' that 'maintains a 1/8 in clearance between the jamb and latch edge'. Hinge screws: '3/4 in minimum through hinges into the slab and frame'; on a solid-core door, 'install a #9 x 2-1/2 in screw in the center hole ... in the top two hinges' so it bites the stud.
Lock prep on a blank slab (Schlage): centerline '38 in from finished floor, or to match other doors on site'; backset 2-3/8 or 2-3/4 in from the edge; '2-1/8 in hole saw' for the cross bore, drilled from both faces so the second side does not blow out; 'Measure and mark 1/2 door thickness' on the edge and drill the edge hole with a 7/8 in bit for a mortise faceplate or 1 in for a drive-in latch; chisel a '1-1/8 in mortise for latch' so it is 'flush with door edge' and a '1/16 in mortise for the strike'. JELD-WEN notes the bore on a factory-prepped slab 'is usually 44 in from the top of the slab'.
Prehung install (JELD-WEN JII109): two people; remove the shipping clips and the nails holding the door closed; set the unit in the opening and 'level the hinge side of the jamb. Use shims fastened through the jamb and stop with 10d finish nails approximately 2 in from the top and 2 in from the bottom'; then 'Level the latch side of the jamb in the same manner ... Ensure the jamb is not twisted and that the spacing between the jamb and door is uniform on all sides'; shim the head in the center; re-check, then 'Nail securely in place through the stop, jamb, shims and into the studs every 12 to 16 in'. Casing goes on with 4d finish nails every 12 to 16 in. 'Failure to install into a square, level and plumb condition could result in denial of warranty claims.'
Floor clearance: prehung 'frames extend below the slab to allow for different floor heights. The jambs can be trimmed as needed before beginning installation, however make sure to leave adequate space to allow air to pass under the door according to ventilation codes'. Measure to the finished floor you will have, not the subfloor, if new flooring is coming (see the vinyl plank guide), and trim the top and bottom of a slab equally rather than all from one end.
The garage door into the house is the one interior door with a code rule. Florida Building Code, Residential R302.5.1: 'Openings from a private garage directly into a room used for sleeping purposes shall not be permitted', and the door to any other room must be 'solid wood doors not less than 1-3/8 inches in thickness, solid or honeycomb-core steel doors not less than 1-3/8 inches thick, or 20-minute fire-rated doors'. A hollow-core slab from the interior-door aisle does not qualify there, and a pet door cut into that door voids the rating.
Permit: Orange County's no-permit list is finish work ('painting ... Replacing flooring ... cabinets or countertops in the same location'), and a like-for-like interior door is treated the same way; nothing published says otherwise. Widening or moving an opening is framing, and in a load-bearing wall it is structural work that needs a building permit. Finish all six sides of the slab 'as well as the frame' before you call it done: JELD-WEN ties the warranty to it.

The permit answer

No permit needed. Exempt finish work under FBC 105.2 and Orange County's published list — but exempt work must still comply with the Florida Building Code.
Source: https://codes.iccsafe.org/s/FLBC2023P1/chapter-1-scope-and-administration/FLBC2023P1-Ch01-SubCh02-Sec105.2

Orange County and the City of Orlando run separate permit offices with separate portals — and your mailing address alone doesn't tell you which one covers your home. Check which permit office covers your address →

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Frequently asked questions

Do I need a permit for an interior door replacement in Orange County, FL?

No permit needed. Exempt finish work under FBC 105.2 and Orange County's published list — but exempt work must still comply with the Florida Building Code.

Are there specific building-code requirements for an interior door replacement?

The garage door into the house is the one interior door with a code rule.

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Sources

https://images.thdstatic.com/catalog/pdfImages/4c/4cb06ad2-90c7-4826-b829-5defd7366184.pdf
https://images.thdstatic.com/catalog/pdfImages/73/7339d7ab-069c-48a6-bc7d-1c390e2c8c28.pdf
https://pdf.lowes.com/productdocuments/b3467431-2468-4243-93a7-f957eb5d3bbf/15608940.pdf
https://us.allegion.com/content/dam/allegion-us-2/web-files/schlage/installation-documents/115799_Schlage_generic_door_prep_knob_lever_no_holes-a.pdf
https://up.codes/viewer/florida/fl-residential-code-2023/chapter/3/building-planning#R302.5.1
https://engageorange.ocfl.net/fast-track-permitting-services/faqs

This guide is general informational content, not professional or legal advice. Codes and county rules change — confirm permit requirements with your local building department, and use a licensed professional for electrical, gas, structural, or main-line plumbing work.