Investigators in Middlebury, Connecticut, are looking into a possible connection between a fire that destroyed a 10,700-square-foot home and the application the same day of spray-foam insulation in a low-ceilinged attic.

A local television news report quoted unnamed fire officials as saying the cause of the fire was polyurethane foam insulation that “spontaneously combusted” in an attic. But on Monday, investigators in Middlebury were careful to say the cause of the July 3 fire had not been determined.

Pinning down a cause officially could be weeks away, Fire Marshal Jack Proulx said.

Proulx said, however, that technicians had been in the house applying foam insulation in an “attic crawl space” on the day of the fire. They were working over a part of the house that connected an indoor pool area with the rest of the house. The technicians were outside the house when the fire was detected.

The house at 725 Break Neck Hill Road was owned by Larry Janesky and his wife Wendy. According to a story in The Hartford Courant, the couple bought the property in 2007 for $5.37 million. It was assessed by the town at $2.95 million.

Janesky owns Connecticut Basement Systems, a basement waterproofing company based in Seymour, Connnecticut, and has written on the topic for Fine Homebuilding magazine. He also owns a company called Dr. Energy Saver, also based in Seymour, that does energy assessments and upgrades, including spray-foam application.

Whether his own crews were working on the house isn’t known.

Foam linked to earlier fires

Three fires in Massachusetts, one of them resulting in a fatality, were linked to the application of spray foam insulation in 2011. Fire investigators suspected the fires were caused by excess heat generated by curing spray foam, according to a July 2011 news story by GBA senior editor Martin Holladay.

Both open- and closed-cell polyurethane insulation is sprayed from a gun that mixes two compounds together. The ensuring chemical reaction that creates the insulating foam is exothermic (that is, it produces heat). If the foam is sprayed in a layer, or “lift,” that’s too thick, or if an insufficient length of time is allowed between lifts, the foam can smolder or burn.

In one of the 2011 fires, a technician named Robert Cowhey was spraying an open-cell, soy-based foam called SoyTherm50 when the fire broke out in the attic of a house that was being renovated. Cowhey died in the blaze.

The Massachusetts fires prompted State Fire Marshal Stephen D. Coan to issue a memorandum to every fire department in the state, warning about possible scenarios that could lead to heat build-up and possibly a fire.

“Based upon this information, the Division of Fire Safety is recommending that you work with your building officials to determine if such applications are taking place within your community and, if so, to also make contractors in your communities aware of this potential fire hazard and encourage that they follow application instructions accurately,” the memo said.

A fire at a net-zero house under construction in Quebec has also been linked to the application of spray foam insulation.

A hot day, a tough fire

Middlebury Fire Chief Paul Perrotti described the fire at the Janesky’s house as a “hot attic fire” that spread rapidly after it was reported about 4:00 p.m. on July 3 as temperatures climbed past 90 degrees.

Fire crews were on the scene within minutes, he said, but were unable to contain the fire. They cut a hole in the slate-covered roof to vent the fire, but the procedure apparently didn’t slow the blaze down. Fire companies from surrounding communities were called in to help.

Perrotti said he had been told at the scene that foam insulation had been sprayed in the house that day, but he said it was not possible to say that was the cause, and he referred questions about the investigation to Proulx. The state fire marshal’s office deferred all comments to Middlebury investigators, although the office said it was possible they had been called to assist.

Although Perrotti said the fire appeared to originate in the attic, or close to it. He also said he had been contacted by the manufacturer of the foam insulation after the fire, but he didn’t recall the name of the company.