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Notched compression face of cantilevered glulam

Notched compression face of cantilevered glulam

Notched compression face of cantilevered glulam

On a project that I am working on I have a 24ft span 5.5x16.5 glulam ridge beam, with 2ft cantilever each end. Well the Architect doesn't want to see a full 16.5" deep ridge at the exterior of the cantilevers.
I searched here and on the APA website and all I have found is the typical information about notching and drilling holes in simply supported glulam beams.

Please refer to the attached pdf of what I am proposing.

What are your thoughts?

Dl & Lr at the 2ft cantilever portion is 210plf & 320plf respectively.


RE: Notched compression face of cantilevered glulam

Be aware that the inner lams have significantly less extreme fiber bending capacity than the outer lams. Precise values can be found with a little digging. I'd try APA-EWS if you can't find them in your books. Your cant is short, so might be OK. A diagonal cut from column face to cant tip, rather than a 90 degree notch would help a lot

RE: Notched compression face of cantilevered glulam

I'd be fine with this. Presumably low stresses and consequences or failure not too dire.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: Notched compression face of cantilevered glulam

Thanks for your input. Yes the bending stress due to the cantilever portion is only 130psi, so even at lower grade inner plies this is well below the allowable. I guess I am just concerned with the plies separating over time.

RE: Notched compression face of cantilevered glulam

Looks o.k. to me too. But, I’d change a couple things, I’d use a 1.5" or 2" dia. auger, or hole saw, not a .5" drill for the reentrant corner radius, they’ll have half a chance of hitting that and cleaning it up a bit. I would countersink the lag screw head and washer so the head was about .4" above the bot. of the beam. That way, if there is any beam shrinkage the head can move down a bit without being driven into the bearing surface.

RE: Notched compression face of cantilevered glulam

I don't see too much to be worried about regarding the stress levels BUT... as you write, "concerned with the plies separating..."
I agree it is a concern as I have seen that plenty of times, usually in older (25 years or more) conditions.
I would guess that a penetrating sealant would be the best approach for this concern.

Regarding the "lag screw" you are showing... IF I was going t use something like that, I would choose a small diameter (like 1/8") continuous threaded structural screw and probably use two of them over the 5 1/2" width.

RE: Notched compression face of cantilevered glulam

Did you determine what the Fc was for the lower grade inner plies? Just curious what the approximate ratio is to the end plies.

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