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#120231 - 04/03/05 12:27 PM I-Joist Drilling  
Admin  Offline

Joined: Oct 2000
Posts: 3,447
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]

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#120232 - 04/03/05 07:29 PM Re: I-Joist Drilling  
Trumpy  Offline

Joined: Jul 2002
Posts: 8,217
SI,New Zealand
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).]

Let's face it, these days if you're not young, you're old - Red Green grin

#120233 - 04/03/05 10:01 PM Re: I-Joist Drilling  
stamcon  Offline
Joined: Mar 2001
Posts: 329
So San Francisco CA
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 Re: I-Joist Drilling  
trollog  Offline
Joined: Oct 2004
Posts: 276
San Diego California USA
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 Re: I-Joist Drilling  
stamcon  Offline
Joined: Mar 2001
Posts: 329
So San Francisco CA

#120236 - 04/04/05 09:41 AM Re: I-Joist Drilling  
Ryan_J  Offline
Joined: Aug 2003
Posts: 1,374
West Jordan, Utah, USA

Ryan Jackson,
Salt Lake City

#120237 - 04/04/05 10:35 AM Re: I-Joist Drilling  
renosteinke  Offline
Cat Servant
Joined: Jan 2005
Posts: 5,316
Blue Collar Country
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 Re: I-Joist Drilling  
Ryan_J  Offline
Joined: Aug 2003
Posts: 1,374
West Jordan, Utah, USA
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 Re: I-Joist Drilling  
walrus  Offline
Joined: Jul 2002
Posts: 680
Bangor Me. USA
Are you using a generic spec sheet or one from the the manufacturer of that particular joist??

#120240 - 04/05/05 06:37 PM Re: I-Joist Drilling  
gideonr  Offline
Joined: Dec 2004
Posts: 161
Edinburgh, Scotland, UK
"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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