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Discussion Starter #1
I have a floor beam under our house that is cracked/split at a knot, and has been that way for several years, with no known problems. I thought this might have been caused by an earthquake, but now read that this is common at knots. I am located in No. Cal., and our house is constructed (as many in this area) with 4x6 beams, or joists, on aprox 4' spacing with a 2x6 subfloor; over a crawl space. The last time I looked at the beam, it did not appear to be sagging. I have been reading a great deal on joist repairs lately, and it appears I could sister this beam with 2x6's on each side. I would plan to support the beam with a jack;...a bottle jack is usually recommended, but I've never seen a hyd jack that doesn't bleed down, unless it has a collar lock. Wouldn't a screw type support jack be more stable ? The 4x6 beams are fir, so is fir the wood to use to sister it? I've seen treated wood and maple, oak or mahogany suggested. I've seen some recommend 1/2 " bolts and some just go with screws. I am thinking a combination, with adhesive on the sistering 2x6's. I could take a picture, but not sure how to post it here.
 

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Discussion Starter #4
OK, It'll be a day or 2, as I have to go under and crawl the length of the house. Not bad once I'm there, but emptying closet to get under is a pain.
 

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Discussion Starter #5
OK, took a little longer than I figured. The beam is a 4x6, 81" from ledger to post support. Cracked area starts 15" from ledge, and is 16" long, then 50" to the post support. The adjacent beam in forground is 18" on ctr, to cracked beam, and then 34" to ledge in background. There is a gap to the subfloor, just above the beam, maybe 1/32". Appears it is worsening from a couple yrs ago, so I better do something this summer.
 

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I think your easiest fix is steel flitch plates on the outside. Jack the left side up to the proper elevation and then through bolt with steel plates on each side so that the cracked area is sandwiched. I would run the plates all the way back to the end of the joist on the wall and stagger lag bolts 8" o/c top and bottom. You would probably want to extend the plates 30" beyond the crack on the right end. Hold the plates back a half inch or so from the top of the joist to make sure you can pass the plates over the wall. 1/4 plate shoudl be good enough and 3/8 lags should work.

What I have outlined is just a spitball (or maybe buck-tooth) design. I haven't designed timber framing for several years. I suggest you contact a local engineer for a full evaluation and repair procedure. I imagine it wouldn't cost but two or three hundred.
 
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