In this historic framing method, builders use exceptionally long vertical lumber to form the exterior walls, with the upper floor joists nailed directly to the sides of these continuous studs. Because the wall cavities are uninterrupted from the basement to the attic, they create natural chimneys that allow fire to spread rapidly between floors. Building codes have largely replaced this method with platform framing, though renovators still encounter it in older homes.
You can't just blow insulation into a balloon frame without adding fire blocking at the floor levels first.
When renovating one of these older structures, inspectors will almost always mandate the installation of horizontal firestops inside the wall cavities.
Also heard as
- Chicago construction
Related terms
Stud
A vertical framing member that forms the core framework of a wall.
Sill
The lowest horizontal structural member of a building, window, or door frame.
Wall plate
A horizontal timber laid flat along the top of a wall to support roof trusses or floor joists.
Firestop
A specialized material or system used to seal openings and prevent the spread of fire.