In balloon-framed walls, the studs are continuous from the mudsill all the way to the top plates on the uppermost floor where the rafters rest.
I’m in the process of renovating an early 1900s home that was constructed using the old balloon-frame method. There were no headers or jack, king, or cripple studs used. When I replace the windows and doors, is there a requirement to install headers and jack, king, or cripple studs, or should I match the methods used throughout the rest of the over 100-year-old house?
— George Carr, via email
Mike Guertin: Balloon-framed walls are different than platform-framed walls; in balloon-framed walls, the studs are continuous from the mudsill all the way to the top plates on the uppermost floor where the rafters rest. Floor joists on the second and third floors are supported by let-in ledger boards, and the joists are usually nailed to the side of the studs. The ledgers essentially act as headers and the studs surrounding the doors and windows act as jack studs, transferring the loads around the openings. Openings on non-bearing exterior walls (walls running parallel to the floor joist system) often don’t have a ledger.
Since your home is an existing structure, you may not have to upgrade the framing unless the replacement windows and doors are larger than the existing wall openings. I’ve replaced windows in many balloon-framed homes and have not been required to reframe the rough openings. However, if you enlarge the opening size, the local official may require you to install platform-style framed headers, jacks, and kings.
To see the codes relevant to your situation, check sections “R102.7: Existing Structures” and “R102.7.1: Additions, Alterations or Repairs” in the 2015 IRC.
From Fine Homebuilding #266