Key Takeaways
- A carbon monoxide (CO) detector alerted a family to a hidden smouldering fire beneath their deck, even though the wood‑burner appeared extinguished.
- Firefighters arrived quickly and found that the fire had already burned through one structural joist, underscoring how rapidly hidden heat can compromise a home.
- While the CO alarm provided an early warning, Fire and Emergency New Zealand stresses that smoke alarms give broader coverage of fire‑related hazards and should be installed in every bedroom, living area and hallway.
- Heating‑related fires rise by about 29 % in winter; keeping flammable items at least one metre from heaters, wood burners and open flames significantly reduces risk.
- Regular servicing of wood burners—especially older units—and annual chimney sweeping are essential preventive measures recommended by fire safety authorities.
Incident Overview
On a chilly evening in late May, Marieke van der Slot‑Verhoeven and her family were settling in for the night when a shrill alarm pierced the quiet of their home. The device that sounded was not a traditional smoke alarm but a carbon monoxide (CO) detector, which had been triggered by an invisible threat lurking beneath the house. At first, van der Slot‑Verhoeven assumed the alarm was a false reading linked to her wood burner, which she had turned off earlier and believed to be cold. The family’s initial confusion quickly turned to concern as they realized something was seriously amiss, prompting them to investigate the source of the alert.
Early Warning from Carbon Monoxide Detector
The CO detector’s activation came as a surprise because the wood burner showed no visible signs of fire—no flames, no glowing embers, and the unit appeared intact. Van der Slot‑Verhoeven recalled checking the burner earlier that night and confirming it was out, leading her to doubt the alarm’s validity. Nevertheless, the persistent beeping compelled her to trust the device and search for any indication of danger. This moment highlighted how CO detectors can sense toxic gases produced by incomplete combustion even when there is no visible smoke, offering a crucial early‑warning layer that smoke alarms alone might miss in certain smouldering scenarios.
Identifying the Source
Following the alarm, van der Slot‑Verhoeven cautiously moved through the house and noticed a faint, acrid smell emanating from beneath the deck adjacent to the fireplace. Upon closer inspection, she observed thin tendrils of smoke curling out from the gap between the deck boards and the foundation. The smoke was not the thick, billowing plume typical of an open flame but a subtle, persistent haze indicative of smouldering combustion deep within the wooden structure. Recognizing that the danger was hidden and potentially spreading, she immediately dialed 111 to summon emergency services, trusting that professional help was needed to address a threat she could not fully see.
Rapid Fire Service Intervention
Firefighters from the Avalon station arrived within minutes, their swift response praised by van der Slot‑Verhoeven as “absolutely fabulous.” Equipped with thermal imaging cameras and portable gas detectors, the crew quickly confirmed that the source of the CO and smoke was a smouldering fire in the floor joists and beams directly underneath the fireplace. The blaze had been burning low and slow, consuming oxygen and producing carbon monoxide without generating enough heat to ignite visible flames. The firefighters proceeded to dismantle sections of the deck and flooring to access the burning material, applying water and foam to extinguish the smouldering embers while ventilating the area to disperse residual gases.
Assessment of Structural Damage
Once the fire was under control, a thorough inspection revealed that the smouldering had already compromised one of the primary joists supporting the deck and the adjacent interior floor. The charred wood showed significant loss of cross‑sectional strength, raising concerns about the long‑term stability of the structure if left unrepaired. Fortunately, the damage was confined to a localized area, and the fire had not spread to load‑bearing walls or the roof. Restoration plans now involve replacing the damaged joist, reinforcing surrounding framing, and inspecting the entire fireplace surround for any hidden heat damage that could precipitate future issues.
Limitations of Carbon Monoxide Detectors
Van der Slot‑Verhoeven expressed unease that her smoke alarm had not sounded during the incident, noting that the smouldering fire was located “just under our bed.” Fire and Emergency New Zealand acknowledged that while CO detectors can provide early warning in certain circumstances—such as this case—smoke alarms are generally more reliable for detecting the particulate matter and visible smoke produced by most fires. The agency explained that smouldering fires may produce insufficient smoke particles to trigger a photoelectric or ionization smoke alarm until the fire grows larger, whereas CO detectors sense the gas regardless of smoke visibility. Consequently, reliance on a single type of detector can leave gaps in protection, especially for fires that begin in concealed spaces.
Official Recommendations on Smoke Alarms
In response to the event, Fire and Emergency reiterated its standard safety advice: every home should have a working smoke alarm in each bedroom, living room, and hallway, with alarms interconnected so that activation in one area sounds throughout the house. They also recommended testing alarms monthly, replacing batteries at least annually, and upgrading to dual‑sensor (photoelectric/ionization) models that respond to both smouldering and flaming fires. For homes with fuel‑burning appliances like wood burners, the agency advises installing a CO detector in addition to smoke alarms, positioning the CO unit near sleeping areas and at least five feet away from fuel‑burning equipment to avoid false readings.
Winter Heating‑Related Fire Increase
The agency highlighted a concerning seasonal trend: heating‑related fires increase by approximately 29 % during the winter months. Colder weather drives greater reliance on wood burners, portable heaters, and open fires, which, if misused or poorly maintained, can ignite nearby combustibles such as furniture, curtains, or bedding. The spike underscores the importance of heightened vigilance when temperatures drop, as the combination of increased appliance use and reduced ventilation can elevate both fire and carbon‑monoxide risks. Public awareness campaigns aimed at winter safety emphasize simple habits—like keeping flammable items at least one metre from heat sources—that can dramatically reduce the likelihood of accidental ignition.
Maintenance and Clearance Guidelines
To mitigate the risks illustrated by van der Slot‑Verhoeven’s experience, Fire and Emergency offers concrete preventive steps. Wood burners should be inspected and serviced by a qualified technician at least once a year, with particular attention paid to the integrity of the firebox, door seals, and flue connections. Older units, which may suffer from corrosion or wear, benefit from more frequent checks. Chimneys must be swept annually to remove creosote buildup—a highly flammable by‑product of wood combustion that can ignite and cause chimney fires. Additionally, homeowners should maintain a clear perimeter of at least one metre around all heating appliances, ensuring that couches, blankets, clothing, and other combustible materials are kept safely away. Installing a non‑combustible hearth pad and using a fire‑screen can further contain sparks and embers.
Lessons Learned and Community Safety
The incident served as a stark reminder that hidden dangers can lurk where they are least expected, and that early detection hinges on having the right safety devices in place. While the CO alarm gave the family a crucial heads‑up, the absence of a sounding smoke alarm revealed a potential blind spot in their detection strategy. Moving forward, the van der Slot‑Verhoeven household plans to install interconnected smoke alarms throughout the home, test all detectors regularly, and adhere strictly to the recommended clearance and maintenance practices for their wood burner. By sharing their story, they hope to encourage neighbours and fellow residents to review their own fire safety setups, especially as winter approaches, thereby reducing the chance that a smouldering ember will go unnoticed until it threatens lives and property.