LYNNWOOD — Firefighters train to be speedy.

Modern homes tend to burn faster than older ones, studies show.

It wasn’t until the past few years that researchers have looked into how fire behaves under various conditions, said Acting Battalion Chief John Puetz, of the Lynnwood Fire Department. Experiments have shown what happens when a nearby door is left open and how construction materials react to fire.

Before the mid-1980s, houses and furniture were typically made of wood. Now, they are more likely a mix of synthetic materials such as plastic, glue and foam, Puetz said.

Man-made materials are easier to manufacture and ship, and they help conserve trees. But the volatile material also acts as kindling.

Important decisions often are made within 10 minutes.

That’s the time it takes for a roof to collapse once flames get into the house’s frame. Older homes with wooden structures might allow crews up to 30 minutes, Puetz said.

He keeps a few places around town on his radar. As more people move to south Snohomish County, housing in Lynnwood has developed quickly. A hotel and two large apartment complexes are planned for construction, and another complex is under review. That doesn’t include the apartment construction site that burned earlier this year near Scriber Lake.

A group of six firefighters who recently joined Fire District 1 traveled to North Bend on Tuesday for training. They met with Puetz and other instructors at the Washington State Patrol Fire Training Academy. Lynnwood and Fire District 1 are sharing resources under a contract while they explore a merger.

Instructors and firefighters reviewed techniques to extinguish fires safely during those crucial 10 minutes after the house’s frame catches fire. During that time, firefighters face the challenges of preserving life and property, dousing the flames and watching out for their own safety.

When Puetz trained at the fire academy about 18 years ago, he was taught to break the windows of burning homes. They thought it cooled the temperature inside. Recent studies show this tactic fuels the fire by providing fresh oxygen.

An open door has the same effect.

Homeowners can help contain a fire in their house by closing doors behind them as they head outside to safety.

District 1 Capt. Jason Isotalo drew out the possible movement of house fires on a whiteboard in one of the academy’s classrooms. The six firefighters played out those scenarios in an empty warehouse where wooden pallets were set ablaze.

The training is based on the results of studies conducted by organizations such as the UL Firefighter Safety Research Institute. One of the experiments simulated a burning living room.

The front door was left open and fans pumped air through the windows. Within a minute and a half, the temperature near the front door rose from 75 degrees to more than 550 degrees.

A person can’t voluntarily touch 400-degree heat, Isotalo said.

In those 90 seconds, the temperature in the living room doubled. Everything in the room ignited. That moment is called a flashover. Anyone inside wouldn’t have time to get out.

“If you see flames floor to ceiling, you know everything is on fire,” Puetz said.

Caitlin Tompkins: 425-339-3192; ctompkins@heraldnet.com