John,
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.
Nice pictures!.



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

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. http://www.osbguide.com/osb.html
steve

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..

Here are some links for hole info. http://www.trusjoist.com/PDFFiles/2031.pdf http://www.lpcorp.com/productfiles/1782LPI20W32US00904.pdf http://www.gp.com/build/DocumentViewer.aspx?repository=BP&elementid=3022

steve

Info here as well:

https://www.electrical-contractor.net/ubb/Forum18/HTML/000053.html

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.

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.

Are you using a generic spec sheet or one from the the manufacturer of that particular joist??

"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!

Always use a sheet that comes from the manufacturer of your specific joist

I saw these joists being made on 'This Old House' via satellite, when Norm (or Steve?) visited a manufacturer. The glue used was 'Recorcinol', which is a catalyst wood glue, ( ie sets by a chemical reaction ) so it won't melt in a fire, just chars.
Rest easy,
Alan

The glue might not melt in a fire, but the web of the joist sure does...rather quickly at that. The only drawback to these is just how quickly they fail in a fire.

Ryan, I will have to beg to differ as to the performance of these joists, and other wood products, in fires.

People see wood, and they think of a blazing campfire. The fats is, as demonstrated daily in ASTM fire tests of various assemblies, wood generally chars, slowly burning through and gradually losing strength. Wood also is a poor heat conductor, so the heat of the fire is not transferred nearly as quickly through the material as it would be with metal.
The bigest surprise is that, where the strengths of the materials are comparable, and especially in a "load bearing" application, wood constructions have a performance in these fire tests virtually identical to steel.
(Not to write steel off....steel can be much, much stronger, allowing for grearer spans, etc.)

I have seen this with all forms of wood products, be they timber, plywood, or engineered.

Interesting...the fire jobs that I have had to inspect the joists failed much quicker than the other wood elements.

Structural steel beams, columns etc. have to be protected by a fire retarding casing, or by 'intumescent' paint, which foams into a carbon-rich protective shell on burning.
This is because at around 660F the iron molecules re-arrange into a "different metal", similar to the structure of aluminium or copper. (BCC molecular lattice changes to an FCC lattice). At around this temperature, though steel actually increases in strength, it becomes very brittle and shock sensitive- known as 'blue-brittleness' due to that being the color of the metal (often seen in tempered tools). Higher than 660F, the strength falls away fast, and by 1550F will rupture at less than 2 tons/sq in. Being a good heat conductor, it will rapidly attain the above temperatures in a fire if not sheathed. If you look at photos of burned buildings, you often see the steelwork has sagged or collapsed. The point of sheathing is to retain some structural integrity long enough to give the occupants of a burning building time to get out. Eventually, practically all common building materials fail in a fire, but wood in thick sections chars slowly, even if directly exposed. I'm not quite so sure about those thin webs, they sure won't give 30 minutes grace once alight, and are a critical structural element of the beams. But, they are usually sheathed themselves by the flooring and ceiling plaster-board (sheet-rock?)- which by the way is a good fire protecting material.
Alan

Guys from my experience as a Fire Officer,
I'd say that given a high enough temperature, anything will burn.
Concrete will burn and that is one of the first things that we look for in an Arson investigation, where an accelerant has been used.
Every material known to Man has an Ignition temperature.

quote
"Every material known to man has an Inition temperature."

Except French barbeque charcoal.

Alan.

I would sooner have a lam beam or tue wood then a prefab truss!!! the nail plates pop off under heat and the truss literally falls apart!!!! Kills alot of Firefighters......

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.

http://search.ebay.com/unibit_W0QQfnuZ1

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.