Stronger Structures with Balloon Framing
What is a Balloon Frame Wall?
A balloon frame wall is a wall that is framed to the full height of the structure, allowing for a continuous load-bearing surface. When we talk about trusses, this means the wall is framed all the way to the roof or, more commonly, to the ceiling line. For example, with a scissor truss, the balloon frame wall is framed up to meet the truss itself.
The primary reason for using a balloon frame wall is to prevent creating what is known as a hinge point. If a wall is framed flat next to a vaulted ceiling, there is a weak spot where outside forces like wind can push the wall inward or outward. In severe conditions such as hurricanes or tornadoes, that hinge point becomes a failure point where a vacuum outside the building could pull the wall out. By attaching the top of the wall directly to the ceiling, the structure becomes much more rigid and resistant to those forces.
Historically, walls were often framed to an eight-foot height regardless of whether there was a vaulted ceiling above. This practice left a hinge point at the transition, making the wall more likely to flex. Balloon framing solves that problem by extending the wall to the actual slope or plane of the truss.
Why Truss Dimensions Matter
In order to properly balloon frame a wall, you need accurate truss drawings from your manufacturer. These diagrams provide the critical dimensions, including horizontal break points and vertical heights, that indicate exactly where the truss transitions from flat to vaulted.
Without these precise dimensions, the wall cannot be framed to match the truss accurately. Even being slightly off at the bottom of the slope can translate into a major error at the top of the wall. This is why it is essential to work directly from the manufacturer’s specifications instead of trying to project the slope with a framing square.
Framing Tips for Balloon Frame Walls
If you are framing in a region where a double top plate is standard, it can be helpful to frame the wall with a single top plate until the trusses arrive. Once the trusses are set, you can add the second plate. This allows for easier adjustments if needed.
Balloon frame walls are typically found on the exterior of a building next to a vaulted ceiling. They may also be used alongside stairwells, where a floor diaphragm is not present to provide stiffness. These walls should always be clearly noted on the plans and called out by the designer or architect. Roof truss layouts often include a matching note to indicate balloon framing as well.
Special Considerations for Scissor and Vaulted Trusses
When framing to match scissor trusses or vaulted trusses, it is important to understand where the slope begins. The slope usually starts inside the wall rather than directly at the outside edge. For instance, with a two-by-six exterior wall, you may come in five and a half inches flat before beginning the slope up to the ceiling pitch. The truss will then pitch back down to match the opposite wall.
Other variations include single-slope vaults where a truss ties directly into the side of a wall. In those cases, you need to confirm whether the truss will have a seat cut built in or if the framer is expected to add a beveled plate on top of the wall to create the seat. It is important to verify this detail with the manufacturer before construction to avoid misalignment.
Wrapping It Up
A balloon frame wall is an exterior wall framed to match the slope of a vaulted truss. The key to building it correctly lies in using precise truss dimensions, both horizontal and vertical, as provided by your manufacturer. Make sure you know whether the truss will be delivered with a flat seat cut or if you will need to adjust the top of the wall with a beveled plate.
The best practice is to measure directly to the break points rather than relying on projection methods. Balloon frame walls are often built flat on the floor and then stood up, so accuracy from the beginning is critical.
These walls are becoming more common, especially on the West Coast, where codes often require balloon framing next to vaulted ceilings. While they can be a challenge, proper preparation and communication with your truss manufacturer will ensure a smooth installation.
If you have questions, reach out to your truss manufacturer for guidance. Having the right measurements and understanding the requirements will save time and prevent costly errors. Balloon frame walls may require extra effort, but the strength and stability they provide make them well worth it.
