# Drilling floor joists



## renovation07 (Dec 3, 2007)

I need to add a 4" dryer vent for an electric dryer. The cavity in the basement that the vent comes through now has many pipes, drains and wires that will make things difficult. The next cavity over is empty. Can I drill a 4" hole in a 2x10 floor joist? The house is old and had hard (oak) joists. The one I want to drill is not under a wall.


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## Kingfisher (Nov 19, 2007)

No:no: Can you make the transition some where else like before you enter the space where the dryer connects?


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## AtlanticWBConst. (May 12, 2006)

No, don't do it.


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## chris75 (Aug 25, 2007)

Holes bored in joists must not be within two inches of the top or bottom of the joist, and the diameter of any such hole must not exceed one-third of the depth of the joist.

If they were bigger than 2x12 joist you would have been okay...


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## ponch37300 (Nov 27, 2007)

Can youuse elbows to go below the joist and then back up into the next cavity? Don't know if this is up to code on venting but thought i would throw it out there. Hopefully someone else will chime in on weather or not this is a good idea. 

I just looked at the ibc and all it said was a maximum of 25 ft of dryer vent and each 45* bend decreases this by 2 ft and each 90* decreases by 5 ft. unless you use long radius bends. So if you don't mind the vent dipping below the joist you should be able to jump it into the next cavity by using 90* or 45* bends.


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## chris75 (Aug 25, 2007)

ponch37300 said:


> Can youuse elbows to go below the joist and then back up into the next cavity? Don't know if this is up to code on venting but thought i would throw it out there. Hopefully someone else will chime in on weather or not this is a good idea.



Never a good idea to "trap" a dryer vent... and probably most likely a code violation...


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## chris75 (Aug 25, 2007)

ponch37300 said:


> I just looked at the ibc and all it said was a maximum of 25 ft of dryer vent and each 45* bend decreases this by 2 ft and each 90* decreases by 5 ft. unless you use long radius bends. So if you don't mind the vent dipping below the joist you should be able to jump it into the next cavity by using 90* or 45* bends.


The IBC is minimum, you still need to use the manufactures instructions, which usually allow up to 70' of duct run...


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## skymaster (Jun 6, 2007)

Atlantic; Hi just for my info mainly; putting all the extra work aside; would it be possible to double header off the adjacent joist, cut it back and hanger it onto the new header? Like one would do for a skylight installation.Then he would be able to NOT trap the line just turn it and go out the rim joist a bit farther down?
Jack


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## Mike Swearingen (Mar 15, 2005)

Although it may be "difficult" to go through the cavity where the existing vent goes through, it looks like the alternatives are even more difficult. I would just go through the existing vent space.
Mike


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## skymaster (Jun 6, 2007)

Mike: Challanges are FUN! LOL LOL. just put in some temporaries, cut the offending joist, header it off, hanger is ROFLOL just drilling a hole and go out is BORING :laughing: :yes:


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