What part of what I said isn't true, and by "a block next to them" do you mean on the left/right, or on the side (behind) that the hatch opens towards? Like I previously said, in A16.4 I had a kill pit that had 4 iron hatches, 2x2, at the top that opened downwards. It was so long ago, and I'm not big on building...just trying to make sure we all know how this and that works, so if I'm wrong, I'd like to know and be sure what is right.
EDIT: Funny story about my kill pit...A new player joined the server I was on through out A16. My base and kill pit with hatches were finished, and I would host horde nights for whoever wanted to join me (sometimes a dozen or more people would show). Shortly before horde night started a new player showed up to seek refuge with us down in my bunker. I showed him the hatches covering the shaft, opened them up, and before I could lead him to the public access door leading down into the upper part of the bunker, the poor guy jumps into the shaft and dies, thinking that was the way in. There were about 6 of us standing there, just looking at the hole the way Master Sergeant Farrel looked at Tom Cruise in Edge of Tomorrow when he tried to sneak off and got run over by the truck, lol.