The floor joists in our 1992 house (new to us) was notched more than
50% in 2 places (to install the A/C ducts) & drilled in another area to
install several small copper pipes. I had 2 contractors come out &
look at the notched floor joists & give an estimate for repairs. One
said it was no problem because: (1) the house is 15+ years old & there
was no evidence of buckling in the floor; (2) the notches are close to
perpendicular support beams in the crawl space and near the concrete
block framework for the crawlspace. A second contractor said it needs
to be repaired & the house may not be up to code because of the
notching (although it is commonly done by contrators when installing
ductwork.

2 questions:

1. Is this a problem that needs to be repaired? (Even though there is
no evidence in the home that it is causing a problem & the places where
the joists were notched are not supporting any heavy pieces of
furniture.)

2. Can I do this repair myself?

- I have an idea of what needs to be done (i.e., scrape out a flat
spot, pour concrete foundation, get 2 concrete cinderblocks [or
concrete blocks designed specifically for this job], then install 2
jacks for each cut out. But what type of jacks? and how tight should
the jacks be against the floor joists to give it enough support?