My home was constructed about ten years ago, and no trap was installed under kitchen sink. Drain drops directly into floor. Counter top holding the sink rests against a half-wall, so It's obviously not vented. Just wondering if there's any connection between venting and use of a p trap. Should I install one?

You need a trap and a vent, but are you sure there isn't a trap below the floor, and a vent within some feet of the short wall? Look at your roof, and also down the chimney if you have one(although venting that way is no longer allowed).

I would install a trap, may even catch a Ring.

The easiest way to see if u have a trap and can not check from below.

Using a piece of string with a small nut as a weight, lower into sink drain until string gets slack. Mark string at top of drain. If u have a trap the bottom will be wet and the length will tell u how far down the trap is.

Chuck

Hi all...

I think Joypulv is correct in checking for the trap and Chuck nailed it by showing you how to check for it unableplumber... ;)

Do what Chuck suggested... if the string comes back wet then you are all set on the PTRAP and, most likely, if the PTRAP is under the floor so is the vent connection. Where the vent goes from there is another issue, but check with the weight and the string to confirm the PTRAP.

Good thinking, Chuck!

Mark