question about framing and load capacity


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Old 11-02-16, 11:48 AM
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question about framing and load capacity

Can someone explain to me just how structurally sound are old houses with balloon framing ? I have a pre war house that was build in the 1920s. Like most pre war houses/buildings in NYC, the ceiling is pretty high (9' to 10' I think). My house also has a tall enough to walk attic thats about 7' at the highest point.

I'm just amazed how every is hold up by 2x4 framing from the exterior wall and a big (8x8?) beam running across in the basement. i guess my question is i don't understand how the floors are on top of 2x10 joists but the joists are hold up by just 2x4 studs.
 
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Old 11-02-16, 12:42 PM
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Still the case (for the most part) that everything above the first floor is supported by 2x4s and exterior sheathing. Balloon framing didn't go out of fashion because it wasn't strong, in fact in some ways (resistance to wind shear) it's stronger because there are no hinge points. It went out of fashion for several reasons: First, the tall stud cavities required fire blocking in every bay to prevent fire from quickly growing up the open stud bays. Second, really long 2x4s were a lot more available (and cheaper) back then. Third, the style of construction now allows the house to be built one story at a time and it is easier to work off floor decks along the way, so it is faster and easier to build.

Floor joists need to be bigger because the load on them is in their weak direction. The primary load on the studs is along the long dimension and is a compression load...wood is quite strong in compression.
 
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Old 11-02-16, 04:46 PM
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Balloon framing is still required in some cases and plenty strong.
In CA exterior walls with a scissor truss above must be ballooned framed, each stud must go up to the bottom of the truss/top plate.
If they trust it here, it should pass anywhere.
 
 

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