We live in a neighborhood of early 20th century bungalows. Sadly, homeowners and house flippers have ruined most of these old houses by removing walls and built-in cabinets in a misguided attempt to remake the interiors into the style that just won’t die: mid century modern. While I’ve been a lone and contrarian voice on this issue, a recent story in the Washington Post tipped me off to an unintended consequence of this open floor plan trend: greatly increased fire danger both for residents and the firefighters who put out those fires. It turns out that all those old walls, doors, windows and traditional flooring materials had a purpose: they made our homes vastly safer.
How much safer? According to research by Underwriters Laboratories (“Analysis of Changing Residential Fire Dynamics and its Implications on Firefighter Operational Timeframes“), in a small, traditional house with individual rooms you’ve got almost thirty minutes to get out before a fire flashes over. In an open floor plan house you have under five minutes, which means that firefighters probably won’t even get to your house before it becomes a raging inferno.
U.L.’s research uncovered a number of alarming trends that they summed up as “larger homes + open floor plans + increased fuel loads [i.e. large sectional couches] + new construction materials = faster fire propagation, shorter time to flashover, rapid changes in fire dynamics, shorter escape times, shorter time to collapse.” It turns out that nobody was considering fire safety as trends in materials and living arrangements have changed in recent years. While the number of structure fires has stayed the same since the 2000s the death rate has increased (U.S. Fire Service Fatalities in Structure Fires 1977-2009 Rita F. Fahy, Ph.D. June 2010).
Let’s take a closer look at some of the unintended consequences of open floor plans and modern materials.
Open Floor Plans
U.L.’s research proves conclusively that open floor plan interiors create fires that spread faster and are harder for firefighters to control.
Another trend in homes is to remove walls to open up the floor plan of the home. As these walls are removed the compartmentation is lessened allowing for easier smoke and fire communication to much of the home. In the living spaces doors are often replaced with open archways creating large open spaces where there were traditionally individual rooms . . . Combining of rooms and taller ceiling heights creates large volume spaces which when involved in a fire require more water and resources to extinguish. These fires are more difficult to contain because of the lack of compartmentation. Water from a hose stream becomes increasingly more effective when steam conversion assists in extinguishment, without compartmentation this effect is reduced. The simple tactic of closing a door to confine a fire is no longer possible in newer home geometries.
Building codes for commercial spaces require a certain amount of compartmentalization. Residential codes don’t require the same level of fire prevention through compartmentalization. In the interest of fire safety, perhaps it’s time we start requiring more walls in new homes and prevent those house flippers from removing walls in old homes.
Synthetic Furniture
Another big factor in house fires has been an increased use of polyurethane foam in furniture. It turns out that foam is more dangerous than the cotton it replaced. I will add that fire spreads faster in particleboard, plywood and MDF than in hardwood (see Flame Spread Performance of Wood Products). All reasons not to pick up that cheap mid-century crap at Ikea! Add the factor of the clutter we all have (also made mostly of synthetic materials) and you’ve got a recipe for tragedy.
Building Materials
The U.L. report goes on to note the superior fire retardant characteristics of traditional lath and plaster over modern drywall.
As drywall compound is heated it dries and falls out exposing a gap for heat to enter the wall space and ignite the paper on the back of the wallboard and the wood studs used to construct the walls. Gypsum wallboard also shrinks when heated to allow gaps around the edges of the wallboard. Plaster and lath does not have the seams that wallboard has and therefore does not allow for heat penetration as early in the fire. This change in lining material allows for easier transition from content fire to structure fire as the fire has a path into void spaces.
Too bad that hardly anyone knows how to do lath and plaster work anymore.
Traditional windows also vastly outperformed modern windows when it comes to fire safety.
The legacy window glass was held in place with putty like substance and there was room in the frame for expansion of the glass. The modern glass was fixed very tightly into the frame with an air tight gasket and metal band, to provide better thermal insulation. This configuration did not allow for much expansion and therefore stressed the glass as it heated and expanded.
Home Size
Small and tiny house proponents will be happy to hear that small is better when it comes to fire safety. The bigger the home the bigger the fire. And the increase in two story homes means fewer paths for egress and more danger for firefighters.
Conclusion
The stark truth is that a small, old house with traditional furniture is a lot safer than a modern open floor plan home with clutter and big couches. House flippers should think twice before ripping out that nice old lath and plaster wall.
