Exactly how old is that historic house?
Consultant uses dendrochronology to date properties
The first time a real estate agent took Ian Stewart to see the old saltbox farmhouse on a rocky hillside in Ghent, New York, he knew he wanted to buy it.
“It got its hooks into me. I loved it. It had a warmth to it,” 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 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 late18th century, he believed.
To find out, he hired William Flynt, of Dummerston, Vermont, 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 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 effect 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.
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, 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 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, 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, 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,” 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.
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,” 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.
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, Massachusetts, 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, 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.
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.
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 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, 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 had hoped, 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.
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.”