On one side of my basement stairs,the doubled 2x10's that frame the opening, only one of the 2x10's sits fully on the steel I-beam. I plan on supplmenting this 2x10 by sistering a third 2x10, running it back 10 feet from the I-beam. (I am unble to run it the full 14 feet) I will then bolt the three 2x10's together. My home was built in 1969, and there is no sagging or deformation at this time. Will this do the job.