Flue Fire Prevention

It is a chilly October evening. A couple in Southampton is entertaining a handful of friends at their home before they all head out to dinner on Main Street. They light a small fire and reminisce over glasses of dry merlot and hors d’oeuvres.

With 15 minutes until their reservation time, they toss a few glasses of cold water over the flaming logs and leave, assuming the dull roar they hear from the chimney is just the fire extinguishing.

Not quite.

Unburned tars and soot—known as creosote, which builds up inside the chimney during every fire—has ignited. The chimney shaft, or flue, warps and cracks. The flames dart out, licking the wood framing and setting the whole house ablaze.

When the couple returns, all that’s left is the brick stack. Their home is in ruins.

This isn’t an unfamiliar tale on the East End. Though in recent years, the number of flue fires has dramatically decreased, according to Southampton Town Chief Fire Marshal Cheryl Kraft. Last year, there was only one local flue fire, she said, which is down from between five and 10 from each of the last two years.

“The old knock on wood, we’ve been having a pretty sane time of it,” Ms. Kraft said during a recent interview. “January was short-sleeve weather, but when it happens, it’s a devastating experience. Left unattended, a flue fire can cause a lot of damage. More people are changing over to inserts.”

Last year, Westhampton Beach Stove & Fireplace saw an overall drop in sales, according to owner Julie Dismore. But sales were brisk for wood, gas and pellet fireplace inserts.

“We put a stainless steel-tubed liner all the way up and down your chimney flue. So if that gets really hot, there’s no cracks in it, no leaks,” Ms. Dismore explained during a telephone interview last week. “If you have an old masonry chimney, if there’s cracks in the flue tiles, that heat is going to eventually get into the wood behind it and cause harm to your house.”

Typically, an insert costs about $5,000, Ms. Dismore reported. She added that those with inserts still need an annual inspection and cleaning, which start at $199.

“I’m not trying to push chimney sweeps, but if you are going to use the fireplace, the investment of a professional coming in to inspect and repair is really worth the cost,” Ms. Kraft said. “If you’re a do-it-yourselfer, you can use a mirror to look up the flue. But really, you’re better off getting a professional.”

Chimney sweeping is the surest way to prevent a flue fire, Ms. Kraft explained, though they weren’t such a problem until the 1930s—when fireplaces became mood-setters, not household essentials or primary heat sources.

“These kinds of fires were less common because people would leave fireplaces running,” she said, noting that the creosote would never harden. “They did cooking on their wood stove, they used them for long periods of time and then wouldn’t allow them to cool down in between. Now, people use them intermittently and, especially, if you don’t have well-seasoned wood or if you’re using soft woods, what happens is you don’t have complete combustion.”

The unburned creosote begins lining the flue, layer upon layer, until it begins to resemble a burnt marshmallow: a gummy mess with portions that are hard and glazed, Ms. Kraft reported.

It is highly flammable, she said. But there are ways to cut back on its buildup.

First, don’t burn garbage—including paper products that may have a plastic finish—or construction materials, such as 2-by-4 pieces of finished wood. Load the fireplace with seasoned hardwoods and make sure there’s a healthy draft to complete combustion.

“If not, the product itself, actually, is what becomes burning. It’ll reach a temperature that will allow it to ignite on the flue wall and as the heat rises, it starts burning upward,” Ms. Kraft said. “That’s when you start hearing the sound. The usual analogy is a roar like a freight train.”

There are other telltale signs that something may be wrong, according to Eastport Fire Department Chief Ryan King.

“Sometimes you might see the air rushing out, hear a popping and cracking sound in the chimney area. The fireplace might start to burn more dramatically in the fireplace itself,” Mr. King said. “Call 911 immediately. Don’t take any chances. That’s the best thing you can do.”