# Floor Joist and bathroom venting



## tony.g (Apr 15, 2012)

bates;973155
Would there be any problem drilling this size hole in about 4-5' worth of floor joists?[/quote said:


> *There certainly would be a problem. On an 8" deep joist, 2 1/2" is about the most you should do.*


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## bates (Dec 4, 2011)

tony.g said:


> There certainly would be a problem. On an 8" deep joist, 2 1/2" is about the most you should do.


 
How am I to route the vent then?


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## tony.g (Apr 15, 2012)

bates said:


> How am I to route the vent then?


That's your problem; you asked if it would be OK to drill a 4" + hole through an 8" deep joist.

You have to work another way round for the ducting. Sorry, but you cannot compromise the structure for ease of getting a duct through.


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## sixeightten (Feb 10, 2009)

If that is only a half bath, you may have more options for venting the fan.


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## tony.g (Apr 15, 2012)

If it's a short run to the outside, will your Code let you use a smaller duct, (say 2") or has it got to be 4"?


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## Beepster (Oct 19, 2009)

Draw us a picture. Why can't you go the longer route that is parallel/in between the joists?

B


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## bates (Dec 4, 2011)

laugh if you'd like at my quick drawing. At work where I don't draw so I had to be quick. Anyways, oddly enough the joist run the same direction as the lines on the paper. 

Top picture is an overview layout of the master bed/bath

Bottom picture shows the change in ceiling height between the bathroom and bedroom (same height) compared to inside the closet height.


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## tony.g (Apr 15, 2012)

Can you get hold of flat, rectangular ducting of the equivalent cross-sectional area? Something like 2" deep by 8" across would do.


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## bates (Dec 4, 2011)

tony.g said:


> Can you get hold of flat, rectangular ducting of the equivalent cross-sectional area? Something like 2" deep by 8" across would do.


 

I'd have to give a look around, sounds like it's not an everyday home depot item?


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## tony.g (Apr 15, 2012)

Have a look at this, particularly diagram 3 on p2, showing the flat ducting (it looks to be 4" x approx 2"). There are adaptors from round to rectangular.

(its a UK firm, but your hd or lowes will have something similar; if the pic. doesn't come through, I can scan it and upload).

http://www.wickes.co.uk/content/ebiz/wickes/resources/images/gil/93.pdf


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## Jim F (Mar 4, 2010)

bates said:


> I'd have to give a look around, sounds like it's not an everyday home depot item?


I found the round to rectangular ductwork at one of those stores HD or Lowes. Please don't bore 4 inch holes in 8 inch joists.You will probably sell that house someday and whomever buys it will inherit that mess and curse you in effigy when they discover it.


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## Evstarr (Nov 15, 2011)

^
Assuming the upstairs tub doesn't come down on top of you first. ...


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## tony.g (Apr 15, 2012)

If its any help to get some extra clearance, you can notch the underside of the floor joists to get the ducting a bit higher up. This is allowable if the notch is not too far in from the ends of the joists, and not too deep.
See this;

http://arch.umd.edu/Tech/Structural...Wood_Products/Notching_&_Boring_Guide_A11.pdf

Most Codes have prescriptive rules for this - check yours. If you decide to notch them, don't go mad with it - you have a bathroom upstairs as well.


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## woody4249 (May 4, 2012)

Is the basement totally below ground level?
Is the bathroom on an outside wall?


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## GBrackins (Apr 26, 2012)

you can run your ventilation duct under the finished ceiling along a wall til you get to the joist bay when you can turn it up and go out. Then enclose the duct in a soffit box and covered with the same finish as the bath room.


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## Beepster (Oct 19, 2009)

bates said:


> laugh if you'd like at my quick drawing. At work where I don't draw so I had to be quick. Anyways, oddly enough the joist run the same direction as the lines on the paper.
> 
> Top picture is an overview layout of the master bed/bath
> 
> Bottom picture shows the change in ceiling height between the bathroom and bedroom (same height) compared to inside the closet height.


I don't get the pic...you haven't explained why you can't go the longer route in between the joists. 

Is it way way too far? Is there stuff in the way?

B


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