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Wood Girder Failure

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jerseyshore

jerseyshore

Structural
May 14, 2015
711
Just went to check out a crawlspace girder because the owner noticed some cracks and a big dip in the first-floor. Double 2x12 spanning approx 8'. Apparently the crawlspace used to be pretty wet and was recently encapsulated.

A contractor had previously installed a 17' attic beam to open up the kitchen wall and of course neither post aligned with the crawlspace piers so they are both sitting on the midspan of this crawlspace girder.

I get down there and find one of the two plys of this girder totally destroyed. Like a combination of a shear failure and compression failure.

In the first photo, you'll see what I thought was a 2x on top of this beam, but no, that's the top 2 inches of this ply totally split clear from the rest of the member and crushed down at least an inch. The 2nd and 3rd photos show this as well.

I've seen a lot of bad crawlspace beams, but don't think I've ever seen one completely sheared off at the top like this.

Any thoughts here if this would really be a shear failure near the top or more likely a constantly damp beam that just crushed because of this new point load.

Will also post the 4th and 5th photos showing the adjacent span of this girder (no point load, just uniform floor loading) with the nails splitting that ply in half as well.

20230530_110446_n70c7b.jpg

#1
20230530_110516_q1swny.jpg

#2
20230530_110459_evaino.jpg

#3
20230530_110306_qb8zgn.jpg

#4
20230530_110313_wi4vmq.jpg

#5
 
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Photos are not very clear.

Can you sketch what you can see to make it better so that we can make sense of the photos.

You can see it in real time but we can't.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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I think the white stuff is the paint or coating they use when encapsulating these crawlspaces. I see it from time to time since encapsulation is very popular in this area.

I can post some additional pics and a sketch when I get home sure.
 
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Jersey Shore crawlspaces are the worst, and my hat is off to you. I'm getting a crawler cam this year. Getting too old to snake crawl through a crawlspace.
 
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Most crawlspaces are a mess around here. No slabs, hanging insulation from the moisture. Ridiculously small access openings. Then once you're in there you have to crawl thru an even smaller opening to get into the second crawlspace. They suck, but it is basically endless work.
 
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Added a very rough sketch and another photo.

This one is pretty clear cut, the entire girder is going to need replacement, I was just more curious if anyone had seen a similar type of failure. And if you would even consider this a shear failure so close to the top. Water is bad for structures, but sure is good for business.

sketch1_n3fm4t.jpg


20230530_110348_yefl1k.jpg
 
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Did you probe the girder to check for rot? That is the only time I have witnessed a failure like that.
 
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Looks like the paint doesn’t go into the cracks, so maybe this is differential shrinkage of axial/tangential grain, brought on by recent low humidity from encapsulating. The nails pinning the beam would restrict movement to result in splitting if one board where quarter sawn and the damaged one flat sawn. Some softwoods can have reaction wood that can have very high differentials, but this may be cupping from the board drying outside-in.

Édit: radial and tangential shrinkage not axial. Question is what is happening? Board is split and so the beam is compromised, and floor is sagging. Why did it split? It looks to be cupping, possibly from curved flat sawn grain, that dried out unevenly. Wood grain, tree rings, tend to want to straighten, and this board has high 2:1 shrinkage ratio and brashness.
 
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I didn't find any obvious signs of rot, that's why I posted to see everyone's thoughts.

It was clearly a very wet crawlspace because there is pretty good crushing happening where the girders are resting on the piers. Super common in this area where the crawls are damp or wet. The current owner said it was a mess when he bought it a few years ago so he got it encapsulated.

I've seen a million open-up-a-kitchen-wall beams that a contractor has put in on the first floor, but they don't do anything below the posts in the basement/crawlspace. And from time to time there are issues, but never a totally crushed piece like this, especially since this was only done in the last few years and isn't supporting some crazy load.

Factoter, this is what I'm thinking as well. I think an actual shear failure is unlikely, and the previously high moisture content that got dried out pretty rapidly caused some serious issue. I didn't realize it before, but in that 3rd photo you can see a nail near the top above the crack, possibly restricting that movement.
 
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Thank you Jerseyshore for the pictures and dirty work. Was a time when I was one of the useful idiots, sent for implementing corrective measures. Crawlspaces bring back many memories, but now encapsulation has become a regular thing, it seems like not such a bad job? One fellow referred to it as crawling around all day on your belly like a lizard. What’s wrong with a full basement?
 
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I'd say 1 out of every 10 crawlspaces have encapsulation around here and they vary in niceness.

I love me full basements. In the rest of the state everyone has basements, but around here, water level is just a couple of feet down. In most of these older houses, they dug down a couple of feet until they hit water and just put the crawlspace/ yankee basement floor just above that.

It's the height that is brutal. Those 16-24" crawlspaces where you can't even sit up are the worst ones.
 
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jerseyshore said:
I think the white stuff is the paint or coating they use when encapsulating these crawlspaces. I see it from time to time since encapsulation is very popular in this area.
Click to expand...

I usually see this in remediated crawlspaces that have had rot/high moisture levels. Just did one and the rot was hard to see and probe but it was there enough to weaken the beams.
 
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The fun ones have dehumidifiers cranked to the max, and the 2x10 girders measure 8.75" deep. I've measured furniture with higher moisture content. Not so great for the drywall, though.
 
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