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Old 01-06-2014, 03:09 PM   #1
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Joist pulling away, floor sag


Hi All,

I purchased a ~100 yr old home in Toronto almost 5 years ago, and am getting ready to attempt some more serious repairs. I have a joist that is pulling away from the support beam, and above it is a noticeable sag in the floor. It doesn't seem to have moved at all in since I have lived here, but I thought it's time to take care of it properly.

I've got some picks below. You can see that the previous owner has added that newer 4X4 with the platform on top (the one with the smoke detector on it) in what I assume was an attempt to fix this. The close-up shows the joist pulling away. Also, the old 4X4 to the left is bending slightly, but not as much as that picture makes it look.



EDIT Repost of second pic apparently didn't work.



So is the correct move to replace that new 4X4 post with a properly footed support post and jack the floor up?

Or should I be following another procedure? Will the joist pull back towards the beam as it is jacked up? Should I install the new post somewhere else?

Thanks for any suggestions. I will be working with a more experienced friend on the job itself, but just wanted to know if I am pursuing the right solution for the problem.


Last edited by jerkbag; 01-06-2014 at 04:58 PM. Reason: This type of link not allowed
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Old 01-06-2014, 04:19 PM   #2
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Joist pulling away, floor sag


For some reason your close up picture didn't post. Back a 100 years ago there were no coated nails like today, they were like our common nails today (uncoated) so they didn't have much holding power.

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Old 01-06-2014, 04:46 PM   #3
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Joist pulling away, floor sag


Can't quite follow your explanation because of the missing pic. But you mentioned jacking up a sagging beam?
If it's 100 years old, the beam will have undergone long-term creep and it may be very difficult to get it straight while not disturbing other parts of the structure.
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Old 01-06-2014, 05:02 PM   #4
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Originally Posted by tony.g View Post
Can't quite follow your explanation because of the missing pic. But you mentioned jacking up a sagging beam?
If it's 100 years old, the beam will have undergone long-term creep and it may be very difficult to get it straight while not disturbing other parts of the structure.
Okay. So maybe just put a proper post in without trying to raise anything? Based on their position, would it be best to replace the newer post, or the bent one to it's left? The sag is on the beam running left to right in the top photo, sagging towards the right at the join.
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Old 01-06-2014, 09:39 PM   #5
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Joist pulling away, floor sag


In your older house, they used a lot of green lumber then- air dried rather than kiln dried so it was much wetter when framed- up to 250% moisture content; real heavy. After framing- the boards dried- more shrinkage across certain directions than others, depending on how it was cut out of the log. Yours is 'plain-sawn" looking at the growth rings on bottom/side; https://www.google.com/search?q=pict...2F%3B386%3B355

This tangential cut; "To complicate things, wood shrinks different
amounts in different directions. Shrinkage parallel
to the annual growth rings (tangential shrinkage) is
twice as much as shrinkage perpendicular to or
across the annual rings (radial shrinkage)."--------- so your board pulled away from the other right after framing when it dried to the house's moisture content.http://www.google.com/url?sa=t&rct=j...F7SWzQ&cad=rja

Coated nails may have helped in dry wood but most coatings (except nylon) lose 50% withdraw power shortly after install and either will lose 75% withdraw power in wet wood, pp.5,6: http://www.google.com/url?sa=t&rct=j...XLQM9w&cad=rja

IMO, jack the new post, add a shim there, fasten it. Add a metal tie strap to secure long-term.

Gary
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Old 01-06-2014, 09:51 PM   #6
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Joist pulling away, floor sag


I should have taken some pictures of the joists in my wife's mom's old place. It was so bad in some places, they were not even on the beam. We could not figure if they were just cut too short, or had shrunk almost 12" in the 100 years that the home had been built.
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Old 01-06-2014, 10:01 PM   #7
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Joist pulling away, floor sag


Quote:
Originally Posted by Gary in WA View Post
In your older house, they used a lot of green lumber then- air dried rather than kiln dried so it was much wetter when framed- up to 250% moisture content; real heavy. After framing- the boards dried- more shrinkage across certain directions than others, depending on how it was cut out of the log. Yours is 'plain-sawn" looking at the growth rings on bottom/side; https://www.google.com/search?q=pict...2F%3B386%3B355

This tangential cut; "To complicate things, wood shrinks different
amounts in different directions. Shrinkage parallel
to the annual growth rings (tangential shrinkage) is
twice as much as shrinkage perpendicular to or
across the annual rings (radial shrinkage)."--------- so your board pulled away from the other right after framing when it dried to the house's moisture content.http://www.google.com/url?sa=t&rct=j...F7SWzQ&cad=rja

Coated nails may have helped in dry wood but most coatings (except nylon) lose 50% withdraw power shortly after install and either will lose 75% withdraw power in wet wood, pp.5,6: http://www.google.com/url?sa=t&rct=j...XLQM9w&cad=rja

IMO, jack the new post, add a shim there, fasten it. Add a metal tie strap to secure long-term.

Gary
Thanks Gary, that is dead on.
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Old 01-07-2014, 08:06 AM   #8
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Joist pulling away, floor sag


Quote:
Originally Posted by Gary in WA View Post
In your older house, they used a lot of green lumber then- air dried rather than kiln dried so it was much wetter when framed- up to 250% moisture content; real heavy. After framing- the boards dried- more shrinkage across certain directions than others, depending on how it was cut out of the log. Yours is 'plain-sawn" looking at the growth rings on bottom/side; https://www.google.com/search?q=pict...2F%3B386%3B355

This tangential cut; "To complicate things, wood shrinks different
amounts in different directions. Shrinkage parallel
to the annual growth rings (tangential shrinkage) is
twice as much as shrinkage perpendicular to or
across the annual rings (radial shrinkage)."--------- so your board pulled away from the other right after framing when it dried to the house's moisture content.http://www.google.com/url?sa=t&rct=j...F7SWzQ&cad=rja

Coated nails may have helped in dry wood but most coatings (except nylon) lose 50% withdraw power shortly after install and either will lose 75% withdraw power in wet wood, pp.5,6: http://www.google.com/url?sa=t&rct=j...XLQM9w&cad=rja

IMO, jack the new post, add a shim there, fasten it. Add a metal tie strap to secure long-term.

Gary
Thanks Gary! This is really helpful. Do you know where I could find a good guide on proper procedure? Would I use a temporary post with jack to raise beam slightly, and then shim the existing post?

shane
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Old 01-07-2014, 01:18 PM   #9
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Joist pulling away, floor sag


We can tell you how, but need another picture of the carrying joist that the stairs are supported from. A little farther back to see the spans.

Gary
PS. That was "boom" time around here and people didn't want to wait a year for the lumber to air dry once they used up the yard reserves. I first got a taste of carpentry (between diesel mechanic jobs) helping my neighbor build his addition- all with green lumber- back in '71 - when we had an abundance of KD lumber- he swore by it.
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Last edited by Gary in WA; 01-07-2014 at 01:23 PM.
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Old 01-07-2014, 01:20 PM   #10
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We can tell you how, but need another picture of the carrying joist that the stairs are supported from. A little farther back to see the spans.

Gary
gotcha I'll take some more when I'm home, thanks.
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Old 01-07-2014, 07:33 PM   #11
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Joist pulling away, floor sag


okay here are some more pictures. Let me know if you need more explanations for any of them.









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Old 01-07-2014, 09:34 PM   #12
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Joist pulling away, floor sag


If this image depicts what's going on, then I would just jack up the joist/beam and tighten up its connection to the other joist/beam with a couple of LedgerLoks. If things are overspanned and you still have a sag, then the post will still be needed. Jack the joist to desired height, shim the gap between joist and existing post, or replace post with a longer one.
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Old 01-08-2014, 12:23 PM   #13
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Joist pulling away, floor sag


I'd replace the sistered studs with a real post though it appears previous owner just laid a landscaping paver on the slab and came off that. Remove the flat 2x4. This would not be a proper footing to distribute any loads to the earth. Do not remove the other post near the new one, it looks original and is required because only a single header joist above is insufficient for the tributary loads on the joist it's carrying without doubling for the span., IMO. I'm surprised the builder didn't double joist at the top of stairs (carrying joist) as he did the headroom end (bottom of stairs) properly though maybe a post there would have constricted the walk room to stairs too severely.

You could use Timberlocs or just 20d spikes (a lot less $$), but that is not why I needed more pictures. As you just had a 5.0 last week, you really need some metal strapping to tie the post to both the header joist and the carrying joist against seismic activity. A 12" section bent around the corner (horizontally) and nailed will tie them together (gap tightening or not). Use post bases or angle brackets to secure the bottoms against kick-out and/or dropping.

Add some strapping to help support/secure the top of stair stringers to the carrying joist, required by all building codes. Cut the end of stringer off- plumb and flush with the back of the carrying joist (opposite stairs) so strap starts 12" down the stringer- bends around/up the back of the joist to floor. You might think about sistering a 2x4 to the sides of the stringers for added support as the material left after the riser/tread notch is less than 5"- our code minimum, yours may be similar. And you have only two stringers with storage in basement.

With your existing knob&tube wiring -- be careful of covering with insulation (as in the attic) to prevent fires.

Gary
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Old 01-08-2014, 02:30 PM   #14
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Joist pulling away, floor sag


Thanks Gary! I think I've got all this, though I might come back with more questions once I begin to tackle it. Just a couple for now:

1) Should I break the concrete and put this new post on a proper footing? And if so, would it's proximity to the second post mean having to replace that one as well?

2) Although I will tie them together, should the new post be positioned to support the header or the carrying joist? Or should I attempt to position it so that the intersection of the header and carrying joist sits in the center of the post?

thanks again,
shane
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Old 01-08-2014, 07:31 PM   #15
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Joist pulling away, floor sag


1. Not yet.....the second one in appears original and extends down below the slab to a proper footing. I would leave that post alone, or shim/replace to lengthen it.

2. Hard to see the stringer/joist connection- it (stringer) appears to be level cut and extend past/under the carrying, perpendicular joist. If so, that is a weak attachment.

3. Is there room to add a hanger on the carrying joist to support the header joist (where gap is at)
? On the existing new flat 2x/post? If the stairs are hung from the carrying joist, a post should be at that joint- where it is now. That would require digging/pouring a new footing under the slab.

Gary

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