I'm 14 is it normal that I'm not allowed in certain rooms?

I come from a big family and am the oldest living at home.My sister is 12 and then my younger brothers are 6,4,2 and triplets are five months. There r some rooms in my house that im not allowed in,do you think that is crzy?Like my parents room i can remember being in ther twice in my life once when i was real sick n another time whn i brought one of the triplets in-but there is a code on the door n we have to knock to get our parents to come out.There is an adult sitting room that is always lokced n im not allowed in without permission n a games room with like a snooker table n fun stuff they ive been in onve with my dad-its totally unfair but my parents say they need adult kid free zones i just wanna be able to hang out wherever n go in the games room with my friends n im not allowed unless my dad is in there too-is it like this in most houses?