Ceiling over Spawn?

[j0sh77]

On my server, we're planning on having a new world to have a war. Inside this world, I made a large rectangular prism of bedrock so nobody could get into the normal world. I'm going to make an age with only tundra and forest for each side of the war.

I'm having a problem creating a ceiling to the original world spawn room. If I build a ceiling, everyone spawns on top. I tried creating a forcefield (thinking it may work), but it resulted in the same thing.

Any ideas on how to fix this?

Thanks in advance!

[Teraku]

Minecraft has weird rules about spawning. How high is the ceiling above the spawn point?

[j0sh77]

I believe spawn is around 100 and the ceiling is at 256

[Teraku]

Can you post a screenshot?