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Sagging Joists


Angus Mc's Avatar
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Join Date: Apr 2007
Posts: 1

04-05-07, 08:02 AM   #1  
Sagging Joists

Hey out there,
I've got a century old farmhouse with 2x8 joists running up to 16' in some rooms on the first floor. These joists are mortised into oak beam which are pretty level due to the addition of posts. My idea is to rip out the old joists, bolt a ledger onto the beam and then tie the new 2x12 or 2x10 joists into the ledger using a shelf or hangers or both. I've put beams under one floor as an experiment but the mortised ends move up or down depending on which side of the room you're walking. Any feedback?-Angus Mc

 
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Jampac's Avatar
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04-05-07, 07:24 PM   #2  
I'm facing the same problem with my house, I was planning on sistering a new 2x to the existing one and using a double joist hanger on the ends. I never thought about the mortised end of the old 2x moving with it being nailed to the hanger.

 
Mephistopheles's Avatar
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05-04-07, 10:11 PM   #3  
....engineer.

 
hammerash's Avatar
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05-27-07, 10:57 PM   #4  
same situation here--107 year old house with rough cut 2x8 spanning 16'. Not sure what you mean about oak beam and posts? where are they? Sorry but am new to this. I don't think I have anything like that. I was just thinking of doing what I think you tried-putting beam (LVL perhaps) underneath joists with posts at ends. I don't understand how you are going to put 2x10 or 2x12 in? Isn't there only about 8" between your sill plate and bottom of subfloor (or in my case there is no subfloor-the hardwoods are right on joists!) since you have 2x8 now?

Bill

 
stickshift's Avatar
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05-28-07, 12:48 AM   #5  
It would, as previously mentioned, be prudent to consult with an engineer on this.

 
hammerash's Avatar
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05-28-07, 07:26 AM   #6  
I already did. I had structural engineer out for something else-my now bankrupt contractor had footer for my addition poured about 3" too high so now we have to figure out how to lower floor so it will line up with my existing floor. My problem is really bouncy floor in old house (deflection) and anything you can do to shorten the span will decrease deflection. In my case, what I mentioned will work fine as a beam underneath the joists shortens the spans they have to carry. But I don't have the mortised beams and posts that were mentioned so I was just curious about that and what it looks like structurally. My joists rest on foundation (the are directly on the mortised stone foundation with no sill plate that I can see!) and carry simple span of about 16'. They didn't have pressure treated back 107 years ago I guess! So why don't the joists rot since they are sitting right on foundation? Maybe cause it is stone and not block or poured concrete and maybe doesn't have moisture problems associated with those types of foundations?

Bill

 
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