Plumbing vent cap—Why is there a hole in it?

**jkwilson** · 08-29-2019, 05:58 PM

Up on the roof doing a midseason inspection today and noticed the plumbing vent cap has a hole in it. Hadn’t noticed it before. Went down to the neighbors and told him I wanted to look at his vent cap. No hole there. Seems like any rain coming in would go to the tank. Just seems like an oddity and can’t figure why it’s there.

**Justa5th** · 08-29-2019, 08:03 PM

Is it possibly a screw hole to hold cap on?

**jkwilson** · 08-29-2019, 08:36 PM

Originally Posted by Justa5th

Is it possibly a screw hole to hold cap on?

It’s a quarter or 3/8ths. Pictures of them on the web show about 50-50 with some having the hole and some not. https://www.etrailer.com/RV-Vents-an.../34474558.html

**Justa5th** · 08-29-2019, 08:49 PM

Originally Posted by jkwilson

It’s a quarter or 3/8ths. Pictures of them on the web show about 50-50 with some having the hole and some not. https://www.etrailer.com/RV-Vents-an.../34474558.html

The description says optional locking screw can be used to better secure the cap. I’m thinking it’s a screw hole. Maybe put a little lap sealant or silicone in it? I would bet it is sealed off unless you put the screw through it.

**gbkims** · 08-29-2019, 10:11 PM

I'd forgotten about the vent's hole. Yep there's a screw in there. It just keeps the cover from popping off.
I'd removed it to look at the pipe coming thru the roof, then reinstalled the cover and screw.
It didn't look like water would leak into the pipe from the hole.