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Hole drilled less than 2" from bottom of floor joist

Hole drilled less than 2" from bottom of floor joist

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Old 04-09-14, 09:46 AM
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Hole drilled less than 2" from bottom of floor joist

I was running coax cable and a friend offered to "help" me. I was very clear to only drill in the center of each joist (never within the bottom or top 2"). Anyways, I was working in the crawlspace and he was working in the main basement. I came back and found he'd drilled one hole out of spec

It's a 1" diameter holr (no idea why as I said to use a 3/4" bit and also not particularly round). It's 1-3/4" from the bottom of the joist (2x8 1920's era wood).

Looking in the basement I found a couple of places where someone previous to my ownership had drilled as close as 1" to the bottom of the joist to run romex though these were closer to the end of the joist. I've lived in the house 10 years and there are no cracks at these locations.

I'm not sure how concerned I should be about this new one at 1-3/4" ?

The standard fix seems to be to glue/nail a 12"x8"x1/2" piece plywood to each side of the joist (overlapping 6" on each side of the hole). If I do this can I drill a matching hole in the plywood at the same incorrect height and rely on the ply to strengthen or do I have to abandon the hole and drill a new hole? I don't really want to be drilling a new hole anywhere near to this existing one?
 
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Old 04-09-14, 09:07 PM
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I'm not sure how concerned I should be about this new one at 1-3/4" ?
That 1" hole there presents no problems at all. It does not present a structural integrity issue.

The major reason for staying away from the bottom of the beams with wiring is so that if the ceiling is sheetrocked the screws don't hit the wires.
 
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Old 04-10-14, 01:09 AM
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Interesting.

IRC R502.8.1 Sawn lumber.
The diameter of holes bored or cut into members shall not exceed one-third the depth of the member. Holes shall not be closer than 2 inches (51 mm) to the top or bottom of the member, or to any other hole located in the member.


I'd assumed the 2" from top/bottom rule was to protect the integrity of the joist (since the bottom is the "tension edge"; not sure about the top) but I can't find anything that specifically states the rationale behind the 2" rule so maybe it is to protect from nails (subflooring or drywall).
 

Last edited by dorkshoei; 04-10-14 at 01:27 AM.
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Old 04-10-14, 03:30 AM
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A hole of consequence, say 2" in diameter could pose structural problems if drilled too close to the edge, hence the rule. A 3/4" hole is of little consequence. Invading the space any closer to the edge will compromise driving fasteners, so it is a two edged sword. Rest easy.
 
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Old 04-10-14, 03:55 AM
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There is a practical side as well, as the location of some joists means they are just providing a nailing place for the floor above. Others are in heavy traffic or load areas where one might be concerned. Regular wood will usually sag over time if under a load and that joist has had plenty of time to tell you what is above. I suspect you could (not saying to do so) completely remove that joist and doubtful anyone above would know the difference. It might put a little spring in their step, but it's not going to come crashing down.

Bud
 
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Old 04-10-14, 05:13 AM
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For about 40 cents each, install a nail plate under the offending holes to protect from ever being hit by another nail or screw in the future. I sometimes recess my nail plates so they don't leave a bulge in the drywall.

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