Really old house with beam deflection


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Old 05-08-08, 07:16 AM
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Really old house with beam deflection

I have a house that was built in the 1740s. The 6x8x16 that supports the attic floor is sagging. The floor joists are mortise and tennon and pegged on 24” centers. The beam is not cracked. My idea is to lift the sagging beam back to level, support the ceiling with 2 temporary walls (the temporary walls will be 2 2x8s screwed together and supported by screw jack poles 4’ on center. Is this over kill or inadequate? ) then cut out the floor joists. Then sister an lvl beam to each side of the 6x8, through bolt the lvls and use joist hangers to reattach the joists.
My questions are how wide lvl or how many lvls should I use in the 6” space I have between the second floor ceiling and the attic floor. Or because of the 6” limit should I consider steel plate? And if so how thick? A ½ inch plate on both sides? Lag bolts to the original beam? Lag bolts instead of through bolts because drilling accurately through all that would be difficult to say the least.

Thanks in advance!!
 
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Old 05-12-08, 06:43 AM
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Just a few thoughts...my gut would be to go with a steel flitch plate however you wouldn't be able to re-hang the joists on the beam. And bolting a couple more LVL's to the sides would make it 9" wide and that's just getting rediculous, and perhaps inadequate. Why not replace the whole beam? That way you could sandwich an appropriately sized steel plate between two pieces of lumber, still allowing you to hang your joists. Below is a link to a good resource for building a flitch beam. You will notice however that the tables do not give allowable loads for beams of depth less than 8". It is my opinion that 3/16" or 1/2" plate would be sufficient, get verification from a local professional that can see it with their own eyes.

http://www.toolbase.org/PDF/DesignGu...litchplate.pdf
 
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Old 05-14-08, 07:05 AM
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First off thanks for the feed back!!

First off thanks for the feed back!!

I don’t mind going 9” wide if it will work. I could go wider if it is appropriate. I’m pretty much a one man show so getting a 16’ piece of steel plate into my attic poses some logistical issues to say the least. But having said that if it is the way to go I will have to deal with it.

Any and all suggestions are greatly appreciated.
 
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Old 05-14-08, 11:29 AM
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well i do understand the logistics of the flitch beam i suggested are somewhat daunting, unless your lou ferrigno before you make a decision on anything, see what your local building officials would suggest, maybe they have an alternative for you.
 
 

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