ECN Forum Forums Photo Discussion Forums Photos for General Discussion I-Joist Drilling

A few helpful hints when working with I-joists:
1. Use a uni-bit to drill holes; it works much faster than an auger, flat bit or hole saw.
2. Be very careful when driving staples into the I section. The wood chip composite acts very much like plywood and starting the staple is difficult, but it is even more difficult to keep from over driving it once it starts to puncture the chip board. I recently received a bad shock when the back of my right hand touched the tips of a staple that was over driven by someone else through the other side of an I-joist. It took me 5 minutes to find the problem because it was not readily visible. And when I did find it, I also found that all the staples that the previous "electrician" had put on that cable were over driven. A couple of my men had some trouble with this and one them purchased a staple gun that shoots staples on romex which works very well. And although cost of the staples is somewhat high, the time savings is significant.
3. I noticed in two of the photos that the mc cable is touching a plastic water line. This is a no-no. Water flowing through the line causes vibration in it and this will eventually rub a hole where it contacts the cable.
4. Don't be concerned with KOs that the manufacturer puts in the joist. Most of the time they don't line up because the carpenter didn't lay them off. Secondly, using the uni-bit I mentioned in #1 above is just as fast if not faster than beating out the KOs. You can drill small diameter holes (1.5 inches or smaller) anywhere except in the top or bottom cords of the joist. Don't touch these at all.
Bob


[This message has been edited by ironman (edited 04-14-2005).]

For us non-US guys, what's a "uni-bit"?

Gideon.

Unibit = Step Drill UK)
Screwfix; D15976
alan

Thanks, Ironman....it sure looks like the MC is touching the line, but there is actually a small space. Another detail that you could not have known is that this is actually a drain line from an A/C drip pan- the water lines on this job are either red or blue poly?.
Luck did play a role...the MC was there first:-)

hey reno, was just wondering why you didnt just drill a large hole down the center of the joists and run all of your wires through that hole?? instead of drilling a bunch of them? just a thought..

The centre of the joist lengthwise has the highest bending stress, the ends the highest shear stress, so it's sensible to avoid these places. Regs usually say between 0.25 and 0.4 of the length of the beam.

Gideon, I don't quite follow you. Are you saying that you should avoid the center of the span?

Mako, I suppose I could have tried something like that...but what you don't see is that, for most of the run, it is rare for two cables to run together for any distance. Also, ther are two completely different electrical systems (240/120 and 480/277), and I tried to separate them as much as possible, to reduce the chances of wires getting mixed up.

Gideon, your comment, while similar to some I'd heard before this job, highlights the importance of getting the mfr specs. In this case, the specs made clear that I could make a small hole ANYWHERE in the web- which often became important, as I dodged around pipes, ducts, and the like.
This also relates to Mako's comment....not only is it a lot easier to drill a small hole, the specs were a lot less restrictive.