How Old Is This Old House?

The first time a real estate agent took Ian Stewart to see the old saltbox farmhouse on a rocky hillside in Ghent, N.Y., he knew he wanted to buy it.

“It got its hooks into me. I loved it. It had a warmth to it,” Mr. Stewart said.

One question continued to nag at him long after the sale went through, however: Exactly how old was the house?

The agent told him the building went back to 1900, but Mr. Stewart, a historic preservationist with a longtime interest in the Dutch architecture of the Hudson Valley — “You can call me a giant history nerd” — knew it was considerably older. It might even date to the late-18th century, he believed.

To find out, he hired William Flynt, of Dummerston, Vt., a historical consultant who practices dendrochronology, a method of dating houses by studying tree-ring patterns in the timber used to build them.

The results would not quite turn out as Mr. Stewart had hoped.

Dendrochronology has been a critical tool in climate research for more than a century, allowing scientists to study long-term changes in weather by measuring the size of tree rings. At Columbia University’s Lamont-Doherty Earth Observatory, dendrochronology has been used to study the impact of climate change on tropical trees in the Andes and evergreens in the Alaska tundra, among other things.

Over time, computer technology has vastly increased the amount of data that can be used to analyze ring patterns, making the process much more accurate, said Edward R. Cook, a research professor at the observatory.

Dendrochronology has also proven valuable in determining the age of old wooden structures, often with eerie precision.

The process involves drilling pencil-sized slivers from the wood in the house, sanding them down and then comparing them to a large computerized database of ring patterns from the same region. The results can often tell you what year the wood was cut, and sometimes even the season.

“When it works, it takes away speculation. It allows you to nail down correctly when specific events occurred — not just the initial construction, but alterations and additions,” said Myron Stachiw, an architectural historian who uses the technology often.

Mr. Flynt, one of a small handful of working dendrochronologists in the United States, has surveyed more than 250 buildings and other structures throughout the Northeast over the years. He typically takes a month or more to “dendro” a house and charges anywhere from $1,500 to $4,500, depending on its size and complexity.

The process can leave a lot of homeowners feeling pretty let down. Vintage houses almost never prove to be quite as old as their owners think they are, Mr. Flynt said.

“Most houses I do, people tend to feel they’re earlier than they are. In some cases they just want to confirm it’s as early as they thought, and it’s not. I’m sure in some cases I’ve disappointed people,” he said.

The farmhouse Mr. Stewart bought in the Hudson River Valley had some features associated with late 18th-century architecture, such as hand-hewn beams and wide-board flooring.

Researching local property records, Mr. Stewart learned that a member of an esteemed Nantucket whaling family, Elihu Coffin, had owned a house in the area in the late 1790s. Could Coffin’s house and the one he had bought be one and the same?

A month after extracting samples, Mr. Flynt sent back his report. The wood in the house had been felled in 1843, well after Coffin had died.

“I have to say, I was a little disappointed. I’d always wanted to own an 18th-century house,” Mr. Stewart said.

Dendrochronology works by turning what used to be educated guesswork into a science.

In the past, pinpointing a house’s age depended on poring through old documents such as deeds and census records.

“But none of that is very definitive,” said Ben Haavik, team leader of property care for Historic New England, which owns 38 properties throughout the region, most of them open to the public.

Local officials often recorded when land was sold but not when house construction began, Mr. Flynt said. “You can sometimes find it in tax records — if you can find the tax records,” he added. “Sometimes the records got lost or the town hall burned and everything disappeared.”

Radiocarbon dating, which measures the rate of decay of radioactive carbon in once-living organisms such as plants and animals, can also shed light on a building’s age, but only within a very broad time period, Mr. Flynt said.

As a result, architectural historians trying to date buildings have had to look for materials and styles associated with a particular time period. A certain method of framing a house might indicate that it was built by English settlers in the early 18th century, for example.

But that approach can be contaminated by what Mr. Stachiw calls a “cultural lag.” Builders can and did continue to use traditional construction methods long after they had lost favor with the industry as a whole or been replaced by newer styles.

That’s still the case, Mr. Stachiw points out. “Even today, what’s happening in L.A., doesn’t get out to deepest Oklahoma for a while,” he said.

The swamp of uncertainty created by previous methods sometimes encouraged local legends about a building’s provenance to fester.

“These stories and myths get woven into the fabric of various communities, and often they achieve mythological proportions, which may be misused,” Mr. Stachiw said.

He himself has been involved in surveys of several properties on Martha’s Vineyard, and “every single one we sampled has been 30 to 50 years younger than earlier identified,” he said.

Mr. Flynt once worked with a TV film crew producing a documentary about the Salem witch trials in the 1690s. They spent an entire day at an old house in Peabody, Mass., long rumored to be the home of John Proctor, who was executed as a warlock in 1692.

But while Proctor’s family was leasing the land at the time, Mr. Flynt was able to establish that the house itself didn’t get built until 1726 at the earliest. The footage filmed at the house was quietly shelved.

Such experiences can often be a tad deflating for local historical societies that may have spent years bragging about a property’s age.

“Everyone who owns a historic house would love to say they have the oldest house in town. They have promoted it. Now they have to say they’re wrong,” Mr. Stachiw said.

In 1968, Mark Danforth’s parents bought and restored a house in Tolland, Conn., that was known to have served as a tavern in the late 1700s. They wanted to live in a place with historic character, he said. “My parents’ friends thought they were crazy. They were living in a nice house, and they sold it and bought this house,” he said.

But for Mr. Danforth, who was 8 at the time, watching the restoration sparked a lifelong interest in local history. “It was very exciting. They were tearing out walls and ceilings, and we’d find little artifacts, like an old bake oven. A child’s shoe with a brass buckle. Parts of an old weaving loom. Old bottles,” he said. “It was a neat thing, just a really neat thing to live through.”

The building was known locally as the Sergeant John Cady House, after a wealthy colonial military officer who owned land in the area in the 1720s, and it would later be designated as such by the National Register of Historic Places, which surveyed the property in the 1980s.

But Mr. Danforth was skeptical. Records indicated that Cady had sold the land on which the house was built to another family in the 1740s, but they said nothing about a house existing at the time, Mr. Danforth said.

Just before selling it a few years ago, Mr. Danforth paid for a dendrochronological survey of the house and learned it had actually been built no earlier than 1753.

While the results proved to be something of a disappointment, it was also a relief to know the truth, Mr. Danforth said. His family had spent years debating just how old the house might be.

The Hamilton, Mass., farmhouse that Kevin Kaminski and Maureen Clarke have spent the past decade renovating came with a plaque saying it was built “circa 1800,” and certain architectural features suggested it might actually be older.

As ardent environmentalists, the couple hoped to use the property to demonstrate that a colonial-era building could be made energy-efficient and even reserved the domain name “netzerocolonial.com.” But first they had to find out how old the house really was.

“We love it, and when you love a thing, you want to understand its history,” Ms. Clarke said.

But Mr. Flynt was able to establish that their house was built no earlier than 1835.

“We did want it to be older. But we love it no less now that we know it’s relatively younger,” Ms. Clarke said.

Not every old house is a suitable candidate for testing. Because pine is much more sensitive to microclimate variations, it’s harder to compile a definitive set of data on tree ring sizes in a particular region, which means buildings made of it rarely yield good results, Mr. Flynt said.

Fortunately, houses erected in the Eastern United States tended to be made of much more suitable woods such as oak or hemlock, he added.

Then there’s the fact that old farmhouses tend to have been changed a lot over the years, with numerous additions and alterations, making it harder to nail down a specific date. Timber framing in one part of a house may suggest one year, while a beam in the room next door suggests another.

Mr. Flynt tries to correct for that by extracting wood samples from as many places in the building as possible, but at times the ambiguity simply can’t be resolved.

Another factor that can complicate things: early American builders sometimes repurposed older wood they scavenged from other properties. But Mr. Flynt said reused wood tends to have telltale holes and marks that make it easy to identify.

It’s also possible that an early builder may have cut down wood without using it for a while. But they probably didn’t let it sit around for too long, Mr. Cook said. “There has to have been a good reason to stockpile wood. They wouldn’t cut logs unless they needed them. These were very practical people,” he said.

Since discovering that his house was not as old as he’d hoped, Mr. Stewart has done a little digging into its history. What he has found is a less illustrious story but still an interesting one, he maintained.

Public records in Ghent suggest that the property was sold by Elizabeth Morehouse to a farmer, Martin Henry, in 1843, the year the house was built. It stayed in the Henry family until 1894.

Details remain sketchy, but Mr. Stewart said he believed the house was originally a small farmstead. He has found remains of a barn and chicken coop on the property, as well as an old garage that dates to the 1940s.

As he tries to piece together the house’s story, dendrochronology has provided “the hard and fast scientific reality” that forms the basis of his research, he said.

“There are so many people who make wild leaps with old houses.” he said. “If that’s what you need to believe to cherish your old house, go for it. But I think houses tell a much more interesting story without having to fabricate their history.”

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