Installing a new beam in crawl space.

Old 04-11-19, 12:38 PM
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Installing a new beam in crawl space.

I'm new here, hope you can help. I bought a house for about $20,000 in Jackson Michigan. I am renting it out very cheaply to a family that needed a stable housing situation. Unfortunately, the situation hasn't proven to be as stable (literally) as hoped. The floors are sagging, and it seems to be getting worse. In the crawl space, there is a large beam (6x8) that supports the joists. The joists are 2x8s that run 28 feet in total, with the beam about a foot off of center. When inspecting the home, I didn't notice that the beam is notched 3/4 of the way through at every joist! Essentially, the beam is actually a 2x6. In the below picture, the beam is on the right, and the joist on the left.

The 2x8 beams (18" OC) are already spanning further than L/360 deflection allows (Only counting the first story loads of 10 dead+40 live) which is about 12 feet. With the undersized beam, it is like they are spanning twice the allowed length. The obvious solution seems to be to put in a new beam to support the joists. Determining the tributary area, and summing the load is simple enough. The house is 30 ft wide so it's 18,000 pounds. Then I select a number of piers (3) and can easily size them depending on soil bearing capacity (2000 psf). Then I have to select a beam that can span between my columns. The beam will be supported with jacks so we can raise it slowly into position. So far so good (I hope).

Now I am stuck on what to do at the connection between the new beam and the sill plate. The bottoms of the joists are at the same height as the bottom of the sill plate. The sill plate also has some past carpenter ant damage, and the beam meets the sill plate at a window. See the picture below.

Now the question is what I should do? I have though of a few options:
1) I can place a new beam directly under the old one, and connect them with hardware of some sort.
2) I can put the new beam offset from the old beam in a location where the sill plate rests directly on the stone foundation and there is no insect damage. I am unclear of how to attach the beam to the sill plate or foundation in this case. Could I get the equivalent of a giant joist hanger?
3) I could build additional piers very close to the existing foundation and support the new beam from them. A single joist would be supported by the cantilevered beam after the last pier. This could happen under the existing beam, or somewhere else.
4) Another solution that the hive mind comes up with.

Any help you can give would be much appreciated.

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