Floor support??

[Terrance Wong]

Steve,

I'm an architect so I know a little bit about structures. Cutting the such a deep notch will weaken the joist greatly...if you notch a 2x10 halfway through, you're essentially left with a 2x5.

Every member will undergo two stresses. A bending moment stress (greatest in the middle of the span), and a shear stress (greatest at the ends, close to a support).

In your configuration, the doubling up of the joist would strengthen the ability to resist shear by about 100%, but would only strengthen the moment by 50%, which of course is better than nothing.

That's why plumbers and electricians are suppose to drill holes down the middle of joists. The top section can still resist compression, and the bottom of the joist can resist tension.

If you want to get the most out of doubling up, is to remove the wire, drill a new hole, than reinstall.

People often double up joists to reduce deflection, but really you should also double up the structural stud walls so that the loads are tranferred down to the foundation.

Regards,

Terrance