Separate the slab from the complete opening
A door slab is the moving panel. A prehung unit includes the slab and its frame. Replacing only the slab can preserve sound jambs and trim, but it still requires hinge, lock, bevel, and clearance fitting. A prehung replacement addresses more of the assembly but can involve interior casing, exterior trim, flashing, threshold height, siding, flooring, and a storm door. Quotes should state which approach is included.
Air leakage is not always a failed door
A draft may come from compressed weatherstripping, an uneven threshold, a missing sweep, a latch that does not pull the slab tight, or gaps between the jamb and rough opening. Weatherstripping is useful only when the door closes squarely against it. Thick seals added to a misaligned opening can make latching worse without controlling leakage.
Water management is different from air sealing
Exterior caulk is one part of a water-managed opening, not the entire system. Head flashing, sill pan or sill detailing, threshold support, exterior trim joints, and drainage direction all matter. If water appears at one lower corner, document the opening during rain and look above it before assuming the bottom seal is solely responsible.
Ordering before diagnosing creates expensive risk
Nominal door sizes do not describe every older opening. Wall thickness, floor height, brickmold, siding return, hinge location, swing, handle clearance, step height, and storm-door projection can affect the unit. Final measurements should be made by the person responsible for fitting the product, after the repair-versus-replacement scope is settled.
When repair or replacement is more likely to make sense
The strongest decision considers operation, water, security, fit, and finish work together.
| Condition | Likely next step | Reason |
|---|---|---|
| Sound slab and frame with loose hinges or failed seals | Repair and adjustment | The main assembly still performs its structural job. |
| Localized jamb or trim damage | Targeted component repair | Only the failed material may need rebuilding. |
| Warped or delaminated slab with sound frame | Consider fitted slab replacement | The moving panel is the primary failure. |
| Widespread rot, distorted frame, or failing threshold | Consider a prehung system | Several interdependent parts need correction. |
| Recurring water with an unclear path | Investigate before ordering | A new unit can leak if the surrounding opening remains wrong. |
This guide covers general repair planning. It is not a structural, electrical, plumbing, environmental, code, or real-estate inspection. Conditions involving licensed trades, regulated materials, major building systems, or an immediate safety concern should be evaluated by the appropriate professional.