Interior Doors: What Actually Matters and Why

Interior doors have gotten lost in a sea of style trends and renovation show shorthand. As someone who replaced every interior door in a 1940s bungalow — thirteen doors over two years — I learned everything there is to know about what makes them work, what makes them fail, and what actually matters when you’re choosing them. Today, I will share it all with you.

Materials

Solid wood is what I ended up with throughout my bungalow, and I would not go back. Oak for the main living spaces, maple for the bathrooms. The weight of a solid wood door closing is unmistakable — there is a finality to it that hollow-core panels simply cannot fake. They also provide genuine sound attenuation, which matters enormously in a house where people keep different schedules. The maintenance concern is real: wood requires painting or staining and does expand in humid summers, but a properly fitted solid door handles this without sticking if the joinery is right.

Composite and engineered doors are a legitimate alternative for people on tighter budgets or in climates with extreme humidity swings. They resist warping better than solid wood and cost substantially less. The visual difference is detectable at close range — the grain patterns have a regularity that reveals their manufactured origin — but from across a room they read well. For closets, I used them throughout without reservation.

Hollow-core doors are appropriate for closets and secondary spaces where sound control and substantiality are not concerns. Putting them on a bedroom in a house with young children or a partner who keeps different hours is a decision you will regret. The sound transmission is genuinely that different from solid alternatives.

Door Types and When to Use Them

Panel doors are the default in most pre-war and traditional homes for good reason — the raised or recessed panels break up the surface in a way that reads as architectural rather than purely functional. My bungalow called for five-panel doors throughout, which required some searching to find profiles that matched what had been original. Getting the profile right matters in period homes; a three-panel Shaker door in a Craftsman house reads as an anachronism.

Flush doors — completely smooth, no visible frame or panel — belong in mid-century modern and contemporary interiors. They look deliberately minimal. In a house with significant architectural character, they often read as cheap even when they are not.

Sliding and pocket doors solve real problems in tight spaces. Pocket doors, which slide into the wall cavity, are the more elegant solution but require building them into new construction or a significant remodel — the wall cavity has to be sized and framed for them specifically. Barn door hardware mounted on the face of the wall is the retrofit alternative that became fashionable a decade ago. The look has been somewhat oversaturated by now, but it solves the space problem legitimately.

French doors between living spaces are, when done right, genuinely beautiful. The glass panes allow light to pass between rooms while maintaining a visual separation. They require more wall space than any alternative and the hardware needs to be carefully considered, but when I see them in homes with the right proportions I have never seen a better solution for the interior connection between a dining room and a living space.

Hardware

The hardware is what you touch multiple times a day, and cheap hardware reveals itself quickly. Mortise locks — the kind that sit inside the door edge rather than in a cylindrical hole — are the period-appropriate choice for pre-war homes and noticeably more substantial in operation than cylindrical locks. The lever handles I chose are oil-rubbed bronze, and matching them across every door in the house required some sourcing effort but produced a consistency that reads as intentional design rather than accumulated decisions.

Hinges matter more than people realize. The hinges carry the weight of the door across decades of use, and undersized or underbuilt hinges will allow the door to sag and eventually fail to latch properly. Three hinges on heavy solid doors, properly mortised into the jamb rather than surface-mounted, are the appropriate specification.

Installation

I tried to install the first door myself and the project took most of a Saturday to complete reasonably well. The subsequent twelve I had installed by a carpenter who did all of them in a day and a half. The economics and quality considerations point in the same direction for most people. Door installation requires the jamb to be perfectly plumb and square, the hinges to be precisely mortised, and the strike plate to be located exactly where the latch will meet it. Any significant error in any of these produces a door that sticks, fails to latch, or swings open under its own weight. These are the kinds of errors that are irritating every single day.

What I would do differently: order all doors at once from the same source, which ensures consistent profiles and pre-machined specifications. Measure every opening before ordering because no two openings in an older house are exactly the same nominal size — the carpenter who installed mine had to trim three of them.

Sound and Energy Considerations

The energy argument for interior doors is modest compared to the sound argument. Solid doors between temperature zones — a bedroom suite, a home office — do reduce heat loss at the margins and allow different zones to be heated or cooled differently. The sound argument is much stronger. A solid-core door reduces sound transmission by roughly 20-25 decibels compared to hollow-core, which translates in practice to the difference between hearing a conversation clearly and hearing that someone is talking. For home offices, bedrooms, and music rooms, this is not a marginal improvement.