Balloon-frame construction had a huge impact on cities in the 19th century. Cities like Chicago expanded upwards and outwards practically overnight with this new method of construction. With lumber size becoming standardized and nails mass produced, carpenters could build a multi-story house in just a few days without the need of a master carpenter. However, with the innovative construction method came a serious threat — the hidden open vertical voids allowed fire to travel to the upper floors within minutes. Today, understanding balloon framing isn’t just a building construction history lesson for firefighters, it’s a matter of life and death.
What is balloon framing?
St. Mary’s Church in Chicago was built in 1833 by architect Augustine Taylor. For around $400, Taylor managed to construct a 36x24-foot church by using unskilled labor and new type of assembly. Taylor eliminated the use of mortised beams and fittings and replaced them with lightweight pre-cut studs, with the entire building held together with mass-produced nails. Many worried the structure would blow away, but it stayed in place and set off a building trend that would change the nation. It was perceived as light and frail, kind of like a balloon, hence the name “balloon construction” or balloon-frame construction.
In residential construction, balloon framing replaced traditional timber framing, which required a highly skilled tradesman to hand cut each beam to width and length. With the introduction of long and lightweight factory-cut studs, balloon framing allowed wall studs to run the entire height of the building. This permitted landowners to build their homes by themselves or employ labor at a lower rate. Balloon frame remained popular until the middle of the 20th century and was eventually replaced by platform framing. This method calls for each floor to be constructed one at a time, adding natural fire stops between floors — the modern-day standard. Even though balloon-frame construction is now obsolete, it still exists in many older neighborhoods, and understanding its construction is vital to firefighters safety.
What do firefighters need to know about fighting balloon-frame fires?
One of the most significant problems with balloon-frame construction is its weakness to fire. The continuous vertical wall spaces that run from the foundation to the roof creates what is commonly referred to as the “chimney effect.” This structural design allows heat and smoke to travel rapidly between floors, reaching the attic or upper levels before visible signs appear.
The floor joists are nailed directly to the long vertical wall studs, rather than separating floors like modern platform construction. This does not produce a natural fire stop to slow vertical fire spread. When there is a fire on the lower floor and it moves into the wall, it can travel unrestricted to the upper floors before being detected.
How to identify balloon framing
The first and most critical step is to engage in pre-incident planning in your district to identify balloon framing. Take time to ride your territory and find structures that appear to be balloon framing. Train your crew to recognize common visual signs:
- Narrow, tall residential homes, often built before 1940, are prime candidates.
- Wood siding, steep-pitched roofs, and homes located in historic districts or older urban neighborhoods are common signs.
- Look for the lack of significant foundation-to-roof architectural breaks that may suggest continuous vertical wall cavities. This is a hallmark sign of balloon framing.
Once identified, these structures should be flagged in department preplanning systems, whether digital or hard copy. Additionally, ensure that Computer-Aided Dispatch (CAD) systems are updated to allow for notes that can be shared to alert responding crews. These structures should also be added to district maps, so all shifts are familiar with their location and characteristics.
Balloon framing firefighter tactics
There are several firefighting tactics that are unique to balloon-frame structures.
Size-up at balloon-frame structures
A strong initial size-up is vital when responding to a fire in a balloon-frame structure. Look for any sign of smoke of fire at the roof line early on. Also check for any visible fire or smoke emerging from more than one floor, especially in areas not directly above the known fire room. Remember, if you see flames on the first floor and in the attic or second floor, this strongly suggests that the fire is running the wall voids. This vertical spread may appear disconnected from the main fire room, leading to initial confusion about fire origin or extent.
Balloon-frame fires can be misleadingly quiet in the early stages. A fire that appears to be confined to a room on the lower floor may have already extended vertically behind the walls spreading to upper rooms or the attic. Firefighters should remain alert of conditions that look too calm on upper levels and conduct early checks for concealed extension. A good sign is the lack of stratified smoke on lower floors, with the smoke traveling up those vertical wall openings like a chimney — the aforementioned “chimney effect.”
Thermal imagers at balloon-frame fires
A thermal imager is an essential tool, not only at balloon-frame fires but all structure fires.
During your 360-degree size-up, use your TIC to:
- Scan exterior walls vertically from basement to roofline.
- Scan upper-level walls and ceiling areas for hidden heat signatures (when interior).
- Focus on areas near chases, stairwells and corners where fire can travel rapidly.
If your TIC reveals significant heat but no visible flame, it may signal pre-flashover conditions inside the wall cavity, warranting immediate action like opening the wall to visibly check with extension or ventilation.
Those hidden voids are small rooms that can build flashover conditions just like a larger room. Crews should remain alert for sudden changes and report any findings to the Incident Commander.
Ventilation of balloon-frame structures
Vertical ventilation must take place soon in the incident to release heat and stop fire from moving up through wall voids. It is vital to remove the heated fire gases as vertical fire spread can quickly compromise the structure and endanger interior crews. Ventilating the structure in these situations must be both aggressive and tactical, with a focused effort on releasing hidden heat and smoke to help interior search and rescue operations and support effective fire control.
Fire suppression efforts in balloon-frame structures
A fire in a balloon-frame structure is rarely considered a bread-and-butter fire. This is one fire for which an alternate method of extinguishment should be considered.
Traditional direct fire attack at the seat of the fire may not be sufficient in balloon framing. Even after knocking down visible flames, hidden fire can continue to burn inside the wall cavities and travel upward or downward. Piercing nozzles can be extremely effective in this situation. These tools penetrate drywall or lath-and-plaster surfaces to deliver water directly into concealed spaces.
Swedish fire services commonly utilize the Fognail piercing nozzle system to combat fires in concealed spaces, such as those found in balloon-frame constructions. The Fognail system is designed to deliver high-pressure, low-flow water fog into areas that are otherwise difficult to access, effectively cooling fire gases and suppressing flames within wall cavities and voids.
Fog nozzles can also be used at a wide-angle setting to apply a fine mist into wall voids, attics or ceiling spaces, absorbing heat and limiting flame spread. When possible, crews should cool suspected hot spots, even if there are no visible flames, especially in multi-story areas where fire may be spreading vertically.
Overhaul conditions at balloon-frame fires
Overhaul in balloon frame structures can be very time-consuming. Crews should be prepared to:
- Pull multiple sections of wall and ceiling materials across all floors.
- Inspect chases, plumbing runs, stairwells and behind baseboards. This is where the TIC really shines, as it allows you to inspect without opening every wall.
- Consider using a Pyrometer, a non-contact thermometer that measures temperature by detecting the thermal radiation that is emitted by an object. It allows for quick, remote temperature readings of any surface. It’s an affordable tool for the company officer.
Final thoughts
Balloon framing is a powerful example of how building innovation can come with hidden risks. While it helped shape America’s cities, its design presents unique dangers for modern firefighters. By recognizing these structures and preparing ahead of time, crews will be better prepared to save lives and property — and themselves. It’s what we know before we arrive that can make all the difference. Be safe and train hard.
