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Floor Joists #153651 10/31/03 02:42 PM
Joined: Aug 2003
Posts: 1,374
R
Ryan_J Offline OP
Moderator
This is an E-mail I recieved this morning from a gentleman.

---------------------------------------------
Ryan,

Can I drill 4.125” holes through the ‘I-Beam’ floor joists (not cutting the 2x2 part, just the web) to get the duct work to the outside of the house for a bathroom fan? I need to drill through three (3) of them near the foundation wall.

John Doe

Senior Sales Manager

---------------------------------------------


How would you answer this question?

[This message has been edited by Ryan_J (edited 10-31-2003).]


Ryan Jackson,
Salt Lake City
Building Codes & Related References
Re: Floor Joists #153652 10/31/03 04:27 PM
Joined: Jan 2002
Posts: 1,457
E
Electricmanscott Offline
Member
Call the manufacturer. They have the engineering info on something like that.

Re: Floor Joists #153653 10/31/03 05:41 PM
Joined: Oct 2000
Posts: 3,961
Bill Addiss Offline
Member
Ryan,

I think Scott's is the only answer possible.

Bill


Bill
Re: Floor Joists #153654 10/31/03 05:42 PM
Joined: Aug 2003
Posts: 1,374
R
Ryan_J Offline OP
Moderator
What can you do without consulting the manufacturer?

I've seen holes for 8" round ducts that didn't create a problem.


Ryan Jackson,
Salt Lake City
Re: Floor Joists #153655 10/31/03 05:46 PM
Joined: Oct 2000
Posts: 3,961
Bill Addiss Offline
Member
Ryan,

If he's not talking about a wood beam I think the only safe answer is to consult the Manufacturer. From what I've learned about engineered beams they are manufactured with different material/characteristics in different places, simply put some parts are stronger than others.

Bill


Bill
Re: Floor Joists #153656 10/31/03 08:01 PM
Joined: Aug 2003
Posts: 64
E
eprice Offline
Member
He's talking about I-beam floor joists, ie. TJIs (from Trus Joist), BCIs (from Boise Cascade), LPIs (from Louisiana-Pacific), etc. Any lumber store that sells them should be able to provide you with an installation guide/flyer that has a hole chart showing what size and where holes many be drilled. Just be sure the hole chart is published by the manufacturer of the particular joists you are drilling. I try to keep one from each of the manufacturers in my office so that I can refer to the correct one.

Re: Floor Joists #153657 10/31/03 11:22 PM
Joined: Aug 2003
Posts: 123
P
Pinemarten Offline
Member
I call them 'micro-lam' beams.
Do they have pre-pressed 'knockout' holes for plumbers and electricians?


Here is a similar link about trusses.
Truss Discussion

(edited to shorten URL)

[This message has been edited by Webmaster (edited 10-31-2003).]

Re: Floor Joists #153658 11/02/03 02:32 PM
Joined: Aug 2003
Posts: 1,374
R
Ryan_J Offline OP
Moderator
This is the answer that I gave the gentleman:
---------------------------------------------
Mr. Doe,

It depends greatly upon where the holes are located in relation to the span. As a rule of thumb with I-joists, you want to stay towards the center of the span for large holes. I have seen holes that would accommodate an 8” round duct through the middle of the span without any problem. If you can, try to stay within the center 1/3 of the span. If you are drilling “near the foundation wall”, you may have a problem. If I were inspecting the job, I would ask for the manufacturer of the product to provide approval.



In my neck of the woods, the suppliers of these products are very helpful to provide this information free of cost. I would consider contacting the supplier (not necessarily the manufacturer) and get their advice.



I’m sorry I don’t have a better answer for you, but the rules for I-joists are not set in stone. They are different depending upon the manufacturer and other variables, such as span, spacing and sizing.

Hope this helps you, Ryan Jackson

---------------------------------------------

Great answers guys! That is exactly the way I view it. I think there is a fine line between helping someone with a question and praticing unlicensed engineering...I'm not willing to cross that line and glad you guys aren't either.


Ryan Jackson,
Salt Lake City
Re: Floor Joists #153659 01/08/04 09:25 PM
Joined: Jun 2003
Posts: 1,143
D
DougW Offline
Member
I know it's late, but down here, most AHJ's will red tag ANY cut micro-lam beam (AKA glue-lam). The TJI 'I' beams (the ones with particle board (OSB) in the middle and 2x2's on the top and bottom have a lot more leeway for access holes. Most Lam beams have to be special ordered with access holes, IIRC.

[This message has been edited by DougW (edited 01-08-2004).]

Re: Floor Joists #153660 01/09/04 10:35 AM
Joined: Aug 2003
Posts: 1,374
R
Ryan_J Offline OP
Moderator
Doug: I also red-tag modifications to engineered lumber. It seems as though they are pretty forgiving, about 90% of the time the engineer will crunch numbers and come back to say that everything is fine...


Ryan Jackson,
Salt Lake City
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