# Max sized hole in rim joist



## stubits (Dec 30, 2008)

Ok, so I am trying to figure out what the maximum sized hole allowable is in a rim joist.

I would like to put two holes (relatively close to one another), both for 4" vents, a bathroom exhaust fan and a dryer vent. The rim joist is 2x12 and the location for the vents is more or less above a door and below a door. Also, there will be a deck ledger attached to the rim joist and the vents would have to go through the ledger board as well. The wall involved is load bearing.

Here is a drawing of what's going on...









And here is an idea of what I'd like to do...










And now for the questions...

So, is this permissible by code? 

How big of a hole can I bore in the rim joist? 

Is it OK for the vents to go through deck ledger board?

If there is a problem with the size of the hole in the rim joist, can I sister it or install a metal plate to compensate?

Any other thoughts?


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## Gary in WA (Mar 11, 2009)

3' from any openings into house- doors, windows, supply air ducting, etc.: http://docs.google.com/viewer?a=v&q...X-cV2r&sig=AHIEtbRqP1_bx_SQclGLup65cYgFwMvULw

Be safe, Gary


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## Houston_Bldr (Apr 27, 2010)

You're fine, just keep the holes tight and try to get them as close to the center of the board as possible. Also try to maximize the distance between the two holes. 

You could add some blocking near the holes that run vertically between the floors, and attach them directly to the existing 2x12. This would provide extra support, but may not be necessary.


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## stubits (Dec 30, 2008)

Gary- Wow, that is great and important info. Thanks for saving me the hassle with the permitting office. I would imagine a boarded up/closed up window doesn't count, right? 

Also, the 3' rule only seems to apply to a dryer vent, what about a bathroom vent? Or a kitchen exhaust? I realize it might be best practice NOT to have them close to a door/window but can it be done? 

And if it can, do you agree with HoustonBlg about going through the rim joist of a load bearing wall as well as a deck ledger? If so, do you have a code reference or other reference? Thanks!!

Thanks for saving me on this one and Houston, thanks a ton for your input.


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## Wildie (Jul 23, 2008)

I have vented through rim joists without a problem. 
However, cutting the ledger board would worry me! 
The rim joist is supported for its whole length by the sill plate, whereas the ledger board is just supported by its fasteners only!
Would it be possible to support the ledger with another ledger, underneath?


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## Gary in WA (Mar 11, 2009)

If there is a point load (window jack and king stud) directly above the hole, add a 2x4,?, to the top 1/2 for carrying the load to the sides of the rim joist. Add extra fasteners to each side of the ledger at the hole treating them as ends. No code, just common sense.

http://pdfdatabase.com/code-check-hvac.html

Be safe, Gary


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## kwikfishron (Mar 11, 2010)

Vents go through Rims and Ledgers all the time.


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## Chemist1961 (Dec 13, 2008)

Just thinking, I I have a neighbor who I believe put in one vent with a y splitter and a damper so the air cannot flow backwards to the second device, for his bathroom fans. I don't know if code allows this, especially if a dryer is involved but there could be an option for you worth researching.


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