There’s a little parlor trick I like to pull when I’m doing consulting at people’s homes. I ask them what year their home was built, and before they can answer, I quickly stop them with a raised hand.
"No, don’t tell me," I insist. After a brief show of Kreskin-like concentration, I give them my guess with a flourish. I’m almost always within five years of the correct year of construction. Often, I’m within two years, and occasionally I’m right on the money. The look of astonishment on the homeowners’ faces is always gratifying.
Like most parlor tricks, this one is easy to explain. It relies on a simple and rather prosaic yardstick found in every house: its doors. Unless the place has gone through one of those ghastly home-improvement-emporium "renovations" — in which case the owners would not bother to call me in the first place — the doors are usually original to the house, offering a clear indication of when the place was built.
Right off the bat, a quick glance at the door panel arrangement will usually get you within 10 or 15 years of the construction date. For example, very tall doors with pairs of narrow vertical panels are a dead giveaway to Victorian-era work, yielding a construction date between 1850 and 1900. This broad range can be further narrowed using another test: The more ornate the doors, the later in the 19th century the house was built.
Doors with four stacked horizontal panels, on the other hand, indicate a Craftsman-era pedigree — roughly 1900 to 1925. Those with a single large recessed panel indicate a vintage between 1925 and 1950 or so. Doors with no panels at all — so-called flush or slab doors — point to a modernist-era construction date between the early 1950s and 1980. Molded hardboard doors imitating various traditional panel arrangements point to a construction date between 1985 and the present.
The type of lockset that’s installed in a door furnishes other clues. If the door has a mortise lock (evidenced by a tall, skinny plate in the door edge and doorknobs fastened to a square shaft by setscrews), the house almost certainly predates 1925, although such locks were still used in basement rooms and garages for another decade or two.
On the other hand, doors with just a small rectangular latch plate in the door edge invariably mean the house postdates 1920 — the year when Walter Schlage invented the easier-to-install cylindrical lockset that quickly drove the mortise lock off the market.
Doorknobs, too, have a tale to tell. Mortise locksets with ornate metal or glass knobs suggest late 19th-century construction dates, while those with plain white, brown or black glass knobs are more typical of early 20th-century houses. Cylindrical locksets with knobs resembling giant glass jewels easily peg a home’s construction date between 1920 and 1935.
Even hinges can provide clues. Ornate hinges with spiky ornamental pins typify Victorian-era houses. Hinges with plain leaves and ball-tipped pins hark from the Craftsman era, but remained popular through the Depression. Hinges with plain, flat-tipped pins indicate houses postdating World War II, while those with round-cornered plates are a hallmark of mass-produced prehung doors, putting a home’s construction date after 1970.