BuddyPress.org

Have a read through this post with particular reference to travel_junkies code which you should be able to modify to prevent access to certain pages/areas if user not registered/loggedout

https://buddypress.org/community/groups/how-to-and-troubleshooting/forum/topic/how-to-make-a-private-community/?topic_page=2&num=15#post-44616