"DaddyMonkey" wrote in message
...
If deflection is the vertical movement of the floor joist span measured
at midpoint, there needs to be a set (known) weight to obtain this
measurement.

A small child standing on the center of the joist will give a different
reading than an elephant.


I am sure not an expert on these matters. From what I can read in my
reference books the deflection factor is based on live load (as in a floor)
or dead load (as in a roof).

Children are permitted in residential construction. Elephants are not
likely.

I'm lazy or I would get the book and quote the "load per square foot"
factor.


Colbyt