I’m curious if anyone knows what type of holes are typically allowed to be drilled through glulams? I need to put a couple of 3/4″ holes through a 5 1/8 x 12 glulam near the end for cable.
thanks,
erik
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You can only drill holes in the middle third of span, both horizontally and vertically.
1) Square and rectangular holes are not permitted.
2) Round holes may be drilled or cut with a hole saw
anywhere within the shaded area of the beam.
3) The horizontal distance between adjacent holes shall
be at least two times the diameter of the larger hole.
4) Do not drill more than three access holes in any 4-foot
long section of beam.
5) The maximum round hole diameter permitted is:
1" in a beam 6" to 7.5" tall
2" in a beam 9" or greater
6) These limitations apply to holes drilled for plumbing
or wiring access only. The size and location of holes
drilled for fasteners are governed by the provisions
of the National Design Specification¯ for Wood
Construction.
7) Beams deflect under load. Size holes to provide
clearance where required.
You say you want to drill a hole near the end. If this something like say a garage door header beam and the ends are resting on 2' or so of wall then you can drill anywhere except within a few inches of where it starts to free span over the opening.
That "middle third" rule can be confusing, if you read it wrong. I think you're saying the middle third from edge to edge, not end to end. Right?
So convenient a thing it is to be a reasonable Creature, since it enables one to find or make a Reason for everything one has a mind to do. --Benjamin Franklin
You are reading it right about edge to edge. The middle third is over the free span area, and like I said anything sitting on the wall except close to the edge where it starts to span is fair game.
All this info is from the Boise Glulam Beam Specifier Guide.
I always keep the manufacturers info on site just in case there are any inspectors questions.
Holes are up to the manufacturer. It depends on things like where the hole is and how heavily it's loaded. Contacting the manufacturer is the only way to get a definite answer.
Rules of thumb - Like drilling in the middle third of the span - Won't carry any weight if you have a building inspector to deal with.
FWIW,
Drill one in my neighborhood without a letter or stamped drawing and you will be looking at a "Red Tag" from my local BI's.
BI's here do not mess around with engineered lumber, if you can't show it to them in official form then forget it.
Contact an engineer or the manufacturer is my advice .