Glulam Beam Checking
jackofalltrades777
| Posted in General Questions on
In hot/dry climates, like the desert southwest, is it normal for new glulam beams to check? Had some glulams delivered and installed in just under 1 week and experienced some noticeable checking. The manufacturer claims it’s “normal” for new beams to do that, especially when being installed in a hot/dry climate.
Just wondering if it is and when does checking become a structural issue?
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Pictures?
picture posted
Here are some pics...
The APA claims this...
Yes but that's for posts, where all the forces are in compression. With a beam the top is in compression, but the bottom is in tension, so it's much more important it is connected to the rest of the beam.
To me that looks a bit worrying. If that crack extends right though, the beam effectively becomes that much shallower. Depth is primarily what gives beams strength. So for instance, if you halve the depth of a beam, it becomes four times weaker.
The initial engineer that looked at it believes it is okay but he stated they can run long lag/timber screws through the bottom board. He said the glulams were 70% oversized for the application so there is a large safety factor built in.
I guess it's another regional thing, but glulams here are reserved for where they would be visible as part of the architecture. In a basement or crawlspace, that would have been done with LVLs.
A few links that may be helpful if you wanted to do a little more evaluation on your own:
https://rosboro.com/wp-content/uploads/2021/10/APA-EWS-R475E-EVALUATION-OF-CHECK-SIZE-IN-GLUED-LAMINATED-TIMBER-BEAMS.pdf
https://www.bc.com/wp-content/uploads/2019/06/BG-1-Glulam-Checking.pdf
Thanks for the links. Per the article. The checking appears to affect the shear/horizontal loads more while bending and tensile strengths are virtually unaffected.
Not sure how that would apply to an ICF wall and a SIP roof. Not much shear issues with ICF walls. I've never seen an ICF "rack" like a wood frame wall would in high winds. Just my amateur observations, since I am not an engineer.
"The checking appears to affect the shear/horizontal loads more while bending and tensile strengths are virtually unaffected. "
That's true if the checking occurs in the parts of the beam close to the ends. If it occurs in the middle third of the span, especially if it de-laminates the plies at the bottom, then it is definitely affecting the amount of deflection it can resist. You can see that reflected in the decision tree (figure 4) in the link.