Minecraft Ps3: Best way to destroy all the top and bottom without missing a single TNT?

I'm building a secret minecraft map, and need to figure out a good way to destroy an entire 50 x 50 ceiling with TNT and a supportive top layer, (Any material for ceiling will do) without 1 TNT being missed or accidentally falling onto bottom map?

Adell

You could:

1. Blow it up and rebuild the outer layer

2. Just break it(takes 4ever)

Blowing it up is the fastest

Jontron