My house was built on a slab, there is a 2" PVC drain coming out of the concrete for my washing machine drain. There is no p-trap and it is the end of the sewer line. I am installing a cleanout as well as venting out the roof. My Question is am I required or should I install a p-trap.

My Question is am I required or should I install a p-trap.
Yes! You must install traps on every fixture that has a drain.(see image) If you don't you open your house up to the city sewer which will allow sewer gas to enter your home. Good luck, Tom

My house was built on a slab, there is a 2" PVC drain coming out of the concrete for my washing machine drain. There is no p-trap and it is the end of the sewer line. I am installing a cleanout as well as venting out the roof. My Question is am I required or should I install a p-trap.
When you say all fixtures does that include toilets?

I don't think it would include toilets as the trap is in the toilet itself

When you say all fixtures does that include toilets?

See the picture below and you be able to see the toilet installation, Thanks.

John

When you say all fixtures does that include toilets?
Of course. Toilets have a built in trap,(see johns image) as do most floor drains. Regards, tom