I know I asked before here about drilling lams and was refrenced to the drilling of engineered joists thread. So here is the proper information. Page 19.
http://www.rosboro.com/techref-glulam/techguide060326.pdf

They are all brand specific, another manufacturer may require/allow something else.

I'm going to have to disagree about that "manufacturer specific" caution.

The sheet referred to in this thread, as wellas other artwork referred to in discussions about I-joists, are nothing more than gussied-up versions of what is available from www.apawood.org

This is the website of the "Engineered Wood Association," a trade association that operates in a manner similar to NEMA. It is safe to consider their info to be "industry recognised consensus standards."

Of course, you still have to know the material you are dealing with!

"know the material" And its loading, and, and, and.....

The safest bet is always the engineer responcable, and if not the data for THAT manufacturer, as 'gussied up' wont cut the mustard when the big $$$ back charge is in contest. CYA!

[This message has been edited by e57 (edited 06-05-2006).]

If your pushing the limit with 1 1/2" bits, multiple holes, etc. you should use the data from that manufacturer.

If you stay safely in the guidelines. Your good.

Know the material.. its wood. With a round hole. The info from the Glulam and I joists is relative in 1 main way. Stay in the middle.

Other manufacturer specs should be close to, if not the same.

IMO.

What about the glulams with the pre stamped holes every 18 inches or so? They are not really punched thru very far, but are they intended to be knocked out (more like beat out) with a hammer? Is it okay to knock them out from any section, since they run the full length of the beam?

BigB thats the I joist we are talking about. I call em engineered floor joists.. but don't really know what they are called.

Heres the link for that tread. https://www.electrical-contractor.net/ubb/Forum1/HTML/006716.html

After re reading that thread I see e57's has a bunch of bad stories about drilling lams.

Whatever the rules may be, one thing drilling structural members and roofs have in common is:

If you screw up, it's going to cost you plenty to get it fixed if you're wrong.Be double sure you're right!

[This message has been edited by renosteinke (edited 06-07-2006).]

If the structure is engineered, you need permission from the engineer before you can put any holes in any member.

"I see e57's has a bunch of bad stories about drilling lams"

Darn straight I do!

I even know a good post tension story, I was in the building at the time, and knock on wood it wasn't me.

Gluelams (or other engineered beams like LVL) distribute stresses a bit differently than I-joists do. With I-joists, so much of the moment of inertia is concentrated at the flange that you can get away with a lot of holes in the web without impacting the strength of the beam by more than 2-3%. Since the cross-section of the gluelams are straight, you don't get the clear-cut flange/web, and a comparable hole will have a larger impact on the strength of the overall beam. Also, generally, these beams are used in situations where the shear stresses are significant, in which case little or no drilling may be acceptable. If it's a standard application (simple floor joist or floor beam) then the manufacturer's specifiers guide will have all the guidelines. (There are differences between the manufacturers, and between manufacturer's product lines- grade of 2x used, type of ply, thickness of ply, etc, so you have to be careful here.) But you really need to check with the engineer- if the member is borderline in strength for the application, the % reduction in strength caused by your hole could cause it to fail or to bounce uncomfortably.

Same goes for 2x members. Dead center in the beam is almost always the best place to drill as it has the least impact on a simply loaded joist. Stress for cantilevers and for continuous spans over a bearing wall is a special case and NOT centered mid-span, but 1/3 span, with a disproportionate amount of the weight of the floor borne by the mid-span support. So, if you've got a large floor held up by 2x4 studs in the middle, please don't go boring 2" holes through them! (Center-boring a 2x4 with a 2" hole decreases buckling strength by 20% and cuts bearing capacity by more than half- though once the drywall/sheathing is up, there is a composite action and the decrease in strength is less pronounced.)

Joists and rafters (and other simple beams) gain strength by the cube of their height, but lose strength by the 4th power of their length- as most people here know, the top is in compression and the bottom in tension. The middle of the beam is (generally) neutrally loaded. Drilling a 1.5" hole in the center of a 12" LVL will reduce the bending strength by less than 1%; drilling a 1.5" hole at the edge of that same reduces the bending strength by 40%! (Even more if it was a square-cut notch and not a round bore) In both cases, shear strength is reduced by about 12%. Of course, this is assuming a simple beam with continuous loading; the engineer will be easily able to point to the beam and tell you exactly where you can drill without causing problems.

[This message has been edited by SteveFehr (edited 06-12-2006).]