I want to reinforce the main level floor in my house by installing sections of 2x10 between the floor joists from underneath. My basement is unfinished so the joists are exposed. I don't have support pillars in my basement as the house is supported by an iron I-beam to meet the code requirement, but this minimum code is not enough and I get too much bounce in portions of the floor. My plan is to run two lines of 2x10 along the length of the floor, each line being half-way between the wall and the I beam.

My question is this - would I achieve greater reinforcement by installing the 2x10s parallel to the floor joists/I beam? Or would it be stronger to "box in" the open section of floor by installing the 2x10s parallel to the floor at the bottom of the joist opening.

Thanks for everyone's input.

__________________
Jonathan

2011 Mazda2
2000 E320 4Matic Wagon
1994 C280 (retired)