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#60837 01/10/06 04:04 PM
Joined: Aug 2005
Posts: 251
T
Member
This is probably a building code but...

Is there a reason we cannot drill a 1" hole in a floor joist 1.25" from the bottom of it?

I ussually drill them low because its easier to drill, easier to pull wire through, and your less likely to carelessly drill through other wires or plumbing. Other wires and plumbing are ussually supported in the middle of the joist so your hole would be under them.

This would be the joists in a basement for example.

I'm getting slack for this. They are wanting it in the middle third of the joists, the reason is probably structural support.


Shake n Bake
#60838 01/10/06 04:17 PM
Joined: Dec 2003
Posts: 751
E
Member
building code requires holes bored in joists and rafters to be at least 2 inches from the edges for structural reasons


Earl
#60839 01/10/06 05:10 PM
Joined: Mar 2005
Posts: 1,803
Member
Check out the 'prefab floor joists' post [lower on this page], for reasons why we don't drill holes willy-nilly in the extreme fibres of any beam.

Alan


Wood work but can't!
#60840 01/10/06 05:37 PM
Joined: Aug 2005
Posts: 251
T
Member
so 2" is safe?


Shake n Bake
#60841 01/10/06 06:00 PM
Joined: Feb 2003
Posts: 67
P
Member
2"s from the top or bottom of the joist and no greater than 1/3 the depth of the joist works for me as an inspector!

#60842 01/10/06 09:49 PM
Joined: Dec 2004
Posts: 209
H
Member
I don't have my code book handy, but I seem to remember no more than 1/4 the depth of the joist for holes.

#60843 01/11/06 04:25 AM
Joined: May 2003
Posts: 2,876
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e57 Offline
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"the reason is probably structural support" Yep!

Yes, do see this thread... https://www.electrical-contractor.net/ubb/Forum1/HTML/006716.html


Mark Heller
"Well - I oughta....." -Jackie Gleason
#60844 01/11/06 07:19 AM
Joined: Aug 2001
Posts: 335
S
Member
Picture what drain gutter guys call a "B" bend ... that's a bend "on the flat" ... we electricians refer to it as "the way you're not supposed to bend 2 wire NM cable". This is the same effect you get on joists with the compression and tension of the joist bending "on the flat". As the joist flexes down (from the static or dynamic forces) the fibers on top of the joist compress while the fibers on the bottom stretch (tension) but the fibers in the center have the least amount of change. That's why the engineers tell us to drill the holes in the center. In real life do the joists actually stretch enough to make a difference? Who knows; that's why they (engrs and architects) get the big bucks.


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