Hi I was wondering if anyone can answer a question about bearing walls. I was always under the impression that bearing walls would have to be built directly over one another so that the loads can transfer straight down. But someone recently told me that they can be offset up to 6″…is this true?
I hope that is a straight forward question. Thanks for any responses.
Replies
In my experience there is no rule of thumb for this. But I've been wrong before. I have set bearing walls farther apart than 6'' more like 20'' but they were designed by an engineer. Typically bearing walls should be stacked. Off setting them would depend on the amount of weight they will bear and what size the joist members are.
All depends on what's under it.
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It depends. but my rule of thumb for no more than a 2 story house is that if the wall is perpendicular to the joists under it, the offset can be up to the depth of the joists with solid lumber. I wouldn't begin to try an offset with Ijoists or open web floor trusses with an engineer to say so.
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What Piffin says, offset equal to joist depth, is what current code says. Larger offsets can be done if an engineer signs off on it. In older buildings, pre-dating the current code, you also find larger offsets. My house has some.
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A remodel I did last year had the first floor bearing wall 30" off the basement girder. It was very noticeable. The floor had a good sag going. I built the new wall over the girder then I had to jack and sister the floor joists to take out the memory
But, the house stood like that for 45 years before I came along
Thanks all....that bout answer my question.
In structures class, they teach that anything beyond the center third of the support (in this case, the wall below) is some form of cantilever. What form, as noted in a previous post, depends on how everything is assembled.
That "third" can be a bit dicey to define, too. Say, just for argument, the lower wall was a steel T section that was 6" wide and 96" tall. The "middle third" of that has to be measured as a moment ar from the centroid of the member. This quickly turns into a relatively esoteric physics & vector problem, and does not answer your question.
We'd have to know a lot more--orientation to joists, deck construction, the "design intent" (like is the deck carrying a cantilever; is there to be a 'clear span' under the bearing wall, above; etc.)