Is it normal i have to announce every time i enter a room?

Carry a spray bottle filled with stinking spoiled milk and spray them with it whenever you catch them beating off.

Try to ridicule them into doing the wanking in their private spaces. Don't announce yourself at all but be as silent as possible, and every time you catch them fapping yet again start to act as if you feel sorry for them.. like "dude, seriously, you still haven't found a girl or guy to fuck?" or start pretending you are trying not to laugh at them and look with a combination of finding it funny as fuck and sort of feeling sorry at the same time.

Also try to immediately do things that would kill any sense of arousal. No giving them time to sneak away start asking about the chores that still need doing or mention politics or ask if they spoke to their mother recently.

Basically causing them to realize that they should choose their fapping grounds carefully as fapping in shared rooms often is a doomed affair. And few things are more frustrating than fapping and having to stop with unfinished while being nagged and totally loosing the mood.

That's pretty shitty man, and downright rude/disgusting of them. Sounds like you just have to grin and bear it for the time being.

Whip it out and join them. This can go several different ways but for the most part will probably change the situation

It does suck, but, better off announcing your arrival than not. I had two roommates in college, one of whom would bang his gf (a craggy-looking, butt-ugly girl) at all hours, and, if you didn't somehow announce or advise you were there, you'd walk in on them. Not what anyone wanted to see, trust me.

Learned my lesson the night I went into the apartment, and found his gf peeing into a cup by the closet..Should have stomped my feet, sang, or called out, hey, I'm home..Would have avoided that mess.

Jerk off with them. It'll totally strengthen your bonds with each other!

Filthy fucking faggots