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RE: stacked joist members

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How old is the house?  What does the floor feel like when you walk on it?  If it just a 1-3/4 x 3-3/4 floor joist, the deflection with a 40 psf live load is 3".  Is there  much deflection in the floor?  What is the flooring?  How is it attached to the joists?  

If the floor is not deflecting or bounces when walked on, the two pieces must be acting together.  Is it possible to remove a joist?  To qualify the structure a load test could be used.

We once worked on a project where the 1" tongue & groove flooring was removed to expose the floor joists.  There were so many joists that were cut and/or notched that it was hard to believe the floor withstood the heavy loads on the structure.  Part of it may have been the flooring redistributed the loads.  We had temporarily shored the floor from below before removing the flooring.  

Gary Loomis, PE


Dear List:
I've just seen floor joists comprised of two members
(each 1¾ " x 3 ¾" ) stacked on their narrow edges in
an old house being renovated. The entire floor (joist
span 12', o/c=16")  is made up of these joists. They
don't appear to be fastened and the mating line
between members is hard to detect.  Can this
arrangement be considered as a single 1¾ " x 7½ "

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