dryer duct construction

[John Arnold]

In the 2006 IRC, where it says that clothes dryer duct joints should run in the direction of air flow, that means the male ends should be pointing in the direction of air flow so lint doesn't get caught, right?

I keep seeing it done backwards, so just checking.

[Ray Norton]

Yes that is exactly what IRC G2439.5 says: "The male end of the duct at overlapped duct joints shall extend in the direction of airflow." But, since the reason is not stated in the code, we can only guess why, and lint could be 1 of several reasons.

[Luigi NI]

exhaust gases need to stay in the vent pipe until it gets outside

[James Duffin]

If I see metal duct and not the flexible vinyl or metal material I usually let it slide. Also the joints are usually taped so you can't tell which way the joints face anyways.

[John Arnold]

If I see metal duct and not the flexible vinyl or metal material I usually let it slide. Also the joints are usually taped so you can't tell which way the joints face anyways.

This was new construction with no dryer hooked up, so I could easily look down the duct inside the wall and see the male end up at the first joint.

[John Arnold]

exhaust gases need to stay in the vent pipe until it gets outside

Not sure what that has to do with the duct joint direction.

[James Duffin]

This was new construction with no dryer hooked up, so I could easily look down the duct inside the wall and see the male end up at the first joint.

Good way to look and see what's going on!

[Jerome Schrenker]

John
That is correct. It is to stop lint from collecting and that is also the reason for not allowing any fasteners to penatrate it.