Fires that start within walls can be extremely dangerous and cause immense damage before being detected. A fire starting in a concealed wall space has the potential to spread quickly and unseen throughout a building. Knowing the common causes of fires originating in walls and being aware of warning signs can help identify issues early and prevent tragedy. This article will examine how fires get going inside of walls, what conditions allow them to grow, and how to spot indicators of a hidden blaze.
Common Causes of Wall Fires
There are a variety of ways that fires commonly begin inside of walls. Some of the most frequent causes include:
Electrical Wiring Issues
Problems with electrical wiring are one of the leading culprits of wall fires. Wires inside walls can short circuit or arc, creating intense heat that ignites nearby combustible materials. This is especially dangerous in older buildings where wiring is not up to modern safety codes. Warning signs of faulty wiring include flickering lights, outlets that spark, and breakers that frequently trip.
Light Fixtures
Heat from light fixtures installed inside walls, such as recessed lighting or track lighting, can ignite insulation, wood framing, or other flammable materials if the fixtures are too close. Using bulbs that are higher wattage than recommended or have loose connections also increases fire risk.
Rodents and Wildlife
Rodents are prone to chewing on electrical wires, potentially exposing the conductors and causing shorts or sparks within walls. Birds and other wildlife can also introduce ignition sources by building nests near heat sources. Flammable nesting materials can easily catch fire.
Wood Rot
If water intrudes into a wall from leaky pipes, roof leaks, or flooding, it can cause wooden structural members to rot and decay. This decaying wood is very easily ignited by even a small heat source.
Nearby Heat Sources
High temperatures from stoves, ovens, chimneys and furnaces on the other side of a wall can slowly ignite materials in the wall through thermal conduction. Insulation helps protect against this, but heat can spread through cracks and gaps.
Combustible Materials
Many materials commonly found inside walls can easily catch fire, including wood studs, drywall, insulation like fiberglass or cellulose, wiring coverings, and vapor barriers. Once ignited, these materials provide fuel for the fire to grow.
How Fire Spreads in Walls
Once a fire has started within a wall, there are several ways it can spread outwards:
Vertical Cavities
Most interior walls have cavities that run vertically from floor to ceiling between studs. Flames and heat travel upwards through these cavities with ease, impacting walls on upper floors within minutes.
Utility Openings
There are often openings in walls where utilities like pipes or wiring penetrate. Fire spreads through these openings into adjacent walls or between floors. This allows a fire to expand beyond the room where it started.
Horizontal Cavities
In multi-story buildings, walls usually have horizontal cavities where floor joists rest on top of wall studs. Fire spreads through these cavities to impact surrounding rooms.
HVAC Systems
Heating and cooling ducts that pass through walls can transport flames and smoke through a structure. A fire can spread room to room via HVAC systems.
Attics and Crawl Spaces
Most walls have gaps at the top or bottom where they meet attics or crawl spaces. This allows fire to spread to these concealed spaces from where it can rapidly expand outward.
Chimneys and Flues
Chimneys create a vertical shaft that a fire in a wall can use to reach the roof. Likewise, flues for furnaces and water heaters provide access from a lower wall to upper spaces.
Windows
As a fire burns inside a wall, window glass eventually cracks or breaks due to thermal stress. This provides oxygen that can fuel the fire’s growth and allow flames to vent outward.
Warning Signs of a Wall Fire
Because wall fires start out of view, being aware of certain signs is crucial to detecting them in early stages when they can still be readily extinguished:
Unusual Odors
Burning or electrical smells that have no obvious source may indicate a hidden fire smoldering inside a wall.
Discolored Walls
Smoke stains or dark areas on walls can hint at heat damage from an unseen fire spreading vertically in a wall cavity. However, soot marks are often not visible until significant fire damage has already occurred.
Cracking Paint or Wallpaper
As fire spreads within a wall, it dries out materials like plaster and wood causing paint or wallpaper to crack and peel away.
Hot Spots on Walls
Feeling for hot areas along walls can identify heat radiating from an unseen fire. Use caution to avoid burns.
Sparks or Smoke
Visible sparks or smoke emanating from cracks or gaps in walls are clear signs of fire. However, this only occurs once a fire is fairly large.
Power Outages
Fires started by electrical issues will often cause short circuits that lead to power failures. Loss of power combined with odd smells or noises warrants investigation.
Preventing Wall Fires
There are several effective ways to reduce the chances of a dangerous wall fire in your building:
Routine Electrical Inspections
Have wiring thoroughly inspected by a qualified electrician at least every 10 years to identify any wiring issues before they lead to fire.
Address Leaks Promptly
Promptly repair any water leaks and dry out soaked walls to prevent decay that makes wood framing prone to ignition.
Seal Penetrations
Seal openings around pipes, cables, ducts, and vents passing through walls to reduce chances of fire spread. Use fire-rated materials.
Insulate Around Heat Sources
Ensure insulation adequately separates potential heat sources like chimneys and appliance flues from combustible wall components.
Firestop Systems
Install fire-rated walls or wall components containing firestopping materials proven to impede flame and heat transfer.
Monitor for Problems
Check for signs of electrical issues or moisture damage and address right away. Don’t ignore warning signs of wall fire hazards.
What to Do if a Wall Fire Starts
If you suspect or confirm a fire inside a wall:
Evacuate Immediately
Get out of the building right away and call emergency services. Do not try to put the fire out yourself.
Shut Off Power
Turn off electricity to the building to prevent sparks from fueling the fire until firefighters arrive.
Alert Others
Knock on doors and yell to notify others inside the building if safe to do so. Never re-enter a burning building.
Do Not Ventilate
Avoid opening windows or doors as extra oxygen can intensify the fire. Let the fire department ventilate properly.
Meet Responders
Go to your prearranged meeting place and direct the fire department when they get on scene. Provide any information about fire location.
Conclusion
Fires starting in concealed wall spaces are an extremely dangerous threat that can elude detection. However, being aware of common causes of wall fires, potential warning signs, and best prevention practices allows you to mitigate risks. In the event a fire does start in a wall, evacuate immediately and leave extinguishing efforts to the fire department. Quick reporting and safe escape must be the top priorities. With proper precautions, the chance of disasters from unnoticed wall fires can be substantially reduced.