reinforcing floor joists in crawlspace

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?
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snipped-for-privacy@gmail.com wrote:

Functionally, the house seems to be o.k. It may not meet code. If you want to "fix" the condition, I wouldn't use jacks as permanent support. Lay down some temporary supports to spread the weight and use jacks to lift the joist slightly above level. Install concrete footings and masonry piers to support joists at level. remove jacks. TB
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snipped-for-privacy@gmail.com wrote:

Functionally, the house seems to be o.k. It may not meet code. If you want to "fix" the condition, I wouldn't use jacks as permanent support. Lay down some temporary supports to spread the weight and use jacks to lift the joist slightly above level. Install concrete footings and masonry piers to support joists at level. remove jacks. TB
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1. If it aint broke, don't fix it.
If you planned to install a heavy hot tub or billiard table right over the spot, I might have some concern.
Any jacks or supports you install do not need to push up hard against the house, they are there to prevent flexing of the joist if a load is placed over it.
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I lean toward this needing fixed, things have a way of going south over time. Whoever cut them was an idiot. I would have the A/C ducts moved to a location where they don't require cuts, and marry new joists to the compromised ones.
I am not a carpenter or engineer, so ymmv.
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Dude, seriously not enough information to help you.
My answers would only be dripping in sarcasm
Engineers get paid for this kind of inspection and solution. DIY, no because of the way you state the problem and your solution.
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Some support can't hurt. It may never be a problem, but with simple support, it can prevent it from being one in another 20 or 50 or 100 years. There are limits on what you can cut out and be code compliant, as well as where it can be cut. I'm not sure of what the code is though so find out for sure.

That can work. The jacks must be a mechanical type, like a screw jack. Bottle jacks can leak over time and then you have no support. Since you have no sag yet, they should be snug, not lifting anything at all. The base must be solid so it does not sink, thus not giving any support.
Only a professional with proper credentials can say what "must" be done but some support is better than no support. As long as you don't lift and stress anything you can do no damage.
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