Is it OK to drill holes in floor joist?


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Old 09-16-04, 09:06 PM
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Is it OK to drill holes in floor joist?

I have 40 year old lumber measuring 1 and 5/8 by 7 inches and a span of 10'-8". The joist is not under a load bearing wall, and they are 16 inches on center.

I need to be able to drill two 2 and 1/2 inch diameter holes from about 36 inches to 46 inches from the bearing end. The holes are for furnace PVC exhaust and intake piping.

I assume that the holes would need to be centered vertically and more than 1/3 of the span from the bearing end.

Is it possible to make these holes in this application? Where can I locate tables with this information?

Thanks
 
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Old 09-16-04, 09:42 PM
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don't have the table in font of me, but my opinion for the price charged, is drill the holes, put in the new plumbing, and go on about you're business.
 
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Old 09-17-04, 04:46 AM
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2.5" PVC as exhaust piping for a furnace, really.

May I suggest that you discuss this with your local building officials.
They have boring tables as will as require slopes and information about fire prevention and carbon monoxide poisoning.
 
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Old 09-17-04, 09:36 AM
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I think he said

(2) one half inch holes not 2.5". I am with dell on this drill and go on.
 
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Old 09-17-04, 01:00 PM
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Not Permissable

Originally Posted by danski0224
I have 40 year old lumber measuring 1 and 5/8 by 7 inches and a span of 10'-8". The joist is not under a load bearing wall, and they are 16 inches on center.

I need to be able to drill two 2 and 1/2 inch diameter holes from about 36 inches to 46 inches from the bearing end. The holes are for furnace PVC exhaust and intake piping.

I assume that the holes would need to be centered vertically and more than 1/3 of the span from the bearing end.

Is it possible to make these holes in this application? Where can I locate tables with this information?

Thanks

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

You cannot bore these holes legally for several potential reasons:

1)Boring a hole 2 1/2" in diameter is not permitted (at least under the 2003 International Residential Code) in lumber 7" deep.

The maximum size a bored hole can be in a floor joist is no greater than D/6 where "D" equals the depth of the floor joist.

In this case, "D" is 7 and D/6= 1.166inches or 1 3/16" maximum bore size.

Your proposed bore size for the holes exceeds the maximum diameter allowed by over 1 full inch and would not be allowed.

2) Also, hole boring must be confined to the first third from the bearing ends only and there shall be no bores in the middle 1/3 or any floor joist.

Where "L" equals the length of the joist, L/3 is the maximum distance from each bearing end in which bores can be permitted.

For your 10' 8" joist, L/3= 128/3 or 42 11/16ths inches. According to your specifications you wish to bore beyond this maximum third by about 4" ie 46"), thereby boring into the middle 1/3 of the floor joist where boring is unpermitted under all circumstances.

So according to the information you have supplied and under the IRC 2003 Code, your proposed boring would not be legal and the pipes would need to be located under the joists.

IRC 2003 Codes sections cited: R502.8 and Figure R502.8

Your local code may vary but will reference the tables required for notching and boring.
 

Last edited by homebild; 09-17-04 at 06:04 PM.
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Old 09-17-04, 02:51 PM
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HOMEBILD,

Thanks for the info.

The vent piping cannot go under the joists because a trap would be created.

I was hoping to go over one more bay to avoid a bush, but the joists change direction where the bush is located. Oh well, time to get the pruning saw....
 
 

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