# Drilling top flange of I-joist.



## Rikki

I was reading another thread about I joists, and this question came to mind.

This happens to me often. The top flange of an I joist is set directly below a wall that I have to drill down through. What's the compliant way to drill the top flange of an I joist?


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## MDShunk

When you're on your next I-joist job, grab one of the manuals stapled to probably a half-dozen different joists throughout the job. This is your "bible". 

The proper course of action when drilling the top flange of an I-joist is to install another I-joist next to it, or install squash blocks on either side of the hole.


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## rexowner

Generally, the right way is to find another way. I am not a structural
engineer, but AFAIK, if you cut the flange, a TJI is basically useless.

How to cut Engineered Lumber is spec'd by the manufactuer. Here is
what we usually encounter:
http://www.ilevel.com/top_literature.aspx
See the Structural Framer's guide.


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## Nildogg

Rikki said:


> I was reading another thread about I joists, and this question came to mind.
> 
> This happens to me often. The top flange of an I joist is set directly below a wall that I have to drill down through. What's the compliant way to drill the top flange of an I joist?


 
beam clamps?


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## Rikki

Nildogg said:


> beam clamps?


******.

Thank you to the other two for your suggestions.


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## Nildogg

Rikki said:


> ******.
> 
> Thank you to the other two for your suggestions.


 
You asked Jerry.


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## rexowner

As long as I am getting in over my head here....

Are you talking about an I-joist parallel/under the wall you need to
drill down, or an I-Joist perpendicular?

Obviously, if it's perpendicular, the best thing would be to move over
to not drill the joist.

If you are talking parallel/under, you would need another beam (e.g.
installing an I-Joist next to it as suggested by MDShunk) next to it.

Squash blocks transfer point loads from top-to-bottom. If the
I-Joist is cut in mid-span, and is not supported along its length
from underneath, Squash blocks are not going to make up for the
compromised flange.


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## Nildogg

rexowner said:


> As long as I am getting in over my head here....
> 
> Are you talking about an I-joist parallel/under the wall you need to
> drill down, or an I-Joist perpendicular?
> 
> Obviously, if it's perpendicular, the best thing would be to move over
> to not drill the joist.
> 
> If you are talking parallel/under, you would need another beam (e.g.
> installing an I-Joist next to it as suggested by MDShunk) next to it.
> 
> Squash blocks transfer point loads from top-to-bottom. If the
> I-Joist is cut in mid-span, and is not supported along its length
> from underneath, Squash blocks are not going to make up for the
> compromised flange.


 
I think its already been established that its not been established.


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## MDShunk

Agreed. If the joist is running parallel with the wall above, and you can't just drill over a couple inches, another I-joist is your only alternative. The lumber yards around here will deliver one in an hour or so with a phonecall. Sometimes, that's your only choice. A 40-dollar i-joist can save you hundreds of feet of wire going some other route.


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## rbj

Rikki said:


> I was reading another thread about I joists, and this question came to mind.
> 
> This happens to me often. The top flange of an I joist is set directly below a wall that I have to drill down through. What's the compliant way to drill the top flange of an I joist?


Unless the TJI's are longspanned TJ570's (3.5" flange) there usually is no reason for not being able to angle a hole over the compression flange to the upper sole plate. I speak from first hand collaboration with Weyerhaeuser for books on dwelling construction wiring and past experience. 

Of course there are times at getting skunked by midspan situations, the best way around that is to avoid pulling NM to the floor joist midspan, but to drill up at the end of the joist to a perpendicular wall above. It sucks, but the GC loves you for it.


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## rbj

*Whoops*

TJI560 = 3.5" flange width.


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