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#120231 04/03/05 12:27 PM
Joined: Oct 2000
Posts: 3,671
Likes: 2
Admin Offline OP
Back on 12-07-04, a thread was started in the NEC forum, "What do you guys think?'" , where the drilling of holes in engineered wood I-joists was discussed.

As luck would have it, at that time I was dealing for the first time with I-Joists. The attached pic shows the results.

On the left side, you can just make out my first run of MC, as it winds back and forth through the totall non-aligned factory knock-outs.

On the right, you can see some much neater runs, which took advantage of holes drilled according to the manufacturers' spec sheet- made available to me through this forum.

Thanks, all!

- renosteinke
[Linked Image]

[Linked Image]

[Linked Image]

#120232 04/03/05 07:29 PM
Joined: Jul 2002
Posts: 8,423
Likes: 3
What sort of material is that in them I-Beams?.
Is it some sort of Laminated Timber?.
I was always told that all penetrations though large wooden beams, had to be on the centre-line of the vertical width of the beam.
I'm told that the compressional forces on the beam materials are zero at this point.
Sorry to pick holes in your work, mate. [Linked Image]
Nice pictures!. [Linked Image]

[This message has been edited by Trumpy (edited 04-03-2005).]

#120233 04/03/05 10:01 PM
Joined: Mar 2001
Posts: 333
Mike, the center web is OSB(oriented strand board) and is probably about ½" thick. The compression and tension forces are dealt with the 2x3 top and bottom chords.

#120234 04/03/05 11:18 PM
Joined: Oct 2004
Posts: 276
reno could you pass along the URL for that datasheet? I have had many a debate with (blockhead) co-workers in real life about this and I would love to see some datasheets that I might pass on. At my shop it seems each guy has his own opinion about what can and can't be done to I beams and Glue-Lams..

#120235 04/04/05 12:26 AM
Joined: Mar 2001
Posts: 333

#120236 04/04/05 09:41 AM
Joined: Aug 2003
Posts: 1,374

Ryan Jackson,
Salt Lake City
#120237 04/04/05 10:35 AM
Joined: Jan 2005
Posts: 5,349
Likes: 1
Cat Servant
Thank you, Ryan. The link you posted is essentially th same as the one posted in the thread I was referring to....I had thought I'd made it easy enough to find the thread from last December.

With the spec sheet in hand, I was able to allay the fears of those who had been taught "no holes," etc. I really don't know how the job could have been completed had I been confined to the "knock-outs."

As a general practice, I did try to place my holes closer to the middle of the web, but I also had many long pulls, and the ductwork usually filled the space, forcing me to work near the edges.

The spec sheet says "an 1 1/2" hole may be made anywhere in the web." I took full advantage of this, as my holes were 7/8".

These joists have webs made of a material similar to particle board, and most seemed to be about 3/4" thick, though some had webs as thick as 1 1/2". The 'flanges' are of pine lumber, approximating a 2x4 with a milled slot for the web. They are manufactured to order, and are made in any length you want. The lumber part is spliced with glued finger-joints, and the webs appear to be butt-glued with a hot-melt glue. Joints are, of course, staggered.

#120238 04/04/05 12:51 PM
Joined: Aug 2003
Posts: 1,374
These joists really are an engineering marvel. When you consider that many of these allow an eight inch hole to be drilled right in the middle of the span, and it does nothing to the structural performance...truly amazing.

Ryan Jackson,
Salt Lake City
#120239 04/04/05 06:37 PM
Joined: Jul 2002
Posts: 680
Are you using a generic spec sheet or one from the the manufacturer of that particular joist??

#120240 04/05/05 06:37 PM
Joined: Dec 2004
Posts: 161
"the webs appear to be butt-glued with a hot-melt glue."

Are you sure? I certainly wouldn't want to be upstairs with a fire rageing below in a building constructed with hot-melt glue! [Linked Image]

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