Given the reactions of studs from the loads above them, how much does the bottom plate distribute the loads over the surface the bottom plate lays on?

  • $\begingroup$ I'm thinking of 2x lumber on concrete, 16 to 24 inches on center, with the length of the wall much longer than the height, but would prefer a generalizable answer if possible. $\endgroup$ Jan 16 '18 at 15:12
  • $\begingroup$ How thick's your concrete? $\endgroup$
    – AndyT
    Jan 16 '18 at 15:19
  • $\begingroup$ How thick the concrete needs to be depends on the maximum psi of the bottom plate, right? That's why I'm asking the question. $\endgroup$ Jan 16 '18 at 15:26

Talking about lumber studs and 2x double bottom plate, under normal load applications and type 5 construction, the base plate as prescribe by applicable code, such as type 5 sheets handed out in the building departments, are adequate and no calculation as for the distribution of loads is needed.

So an even distribution is assumed!

However if there is concentrated load on a 3x or larger size post, it has to be calculated and dealt with, with additional possible load factors and penalties for discontinued loading and other special cases.

  • $\begingroup$ In the case where a point load is large enough to require a tripled stud so that that calculation is required, how can the distribution be estimated? $\endgroup$ Jan 16 '18 at 15:10
  • $\begingroup$ Any chance of providing a reference to a table or book for calculating such factors and load penalties? $\endgroup$ Jan 16 '18 at 16:32
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    $\begingroup$ I can rephrase relevant parts of code from my reference, except I am not sure it work in your case. I would as a first estimate assume the load passes right through the bas-plate. In city of Los Angeles you have to multiply by 2.8 post loads tributary to overturning moment from a shear wall on a higher level supported by a beam or a wall. Need to check the whole building! $\endgroup$
    – kamran
    Jan 16 '18 at 18:37

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