Building a vault

BattleCorp

I'm in the initial stages of planning to build a strongroom in my shed. Nothing mad expensive to be stored inside, just stuff I'd rather not have stolen. I have the vault door so basically I've to build the room now, approx. 20m2.

Two questions. Hopefully not too stupid.

Which is cheaper? Concrete blocks or mass concrete?

Would blocks laid on the flat be strong enough for a strongroom? I'm thinking probably not.

scwazrh

https://www.boards.ie/discussion/2058283673/building-a-vault

Shutter and pour concrete with rebar is the best way for it .9” thick min.The roof is the most awkward part .Pre cast slabs are best if possible or joists reinforced with mesh over and also steel sheets .

BattleCorp

The only place I can put it won't allow me to install precast slabs. Not enough room to get them lifted in place.

I was thinking of propping plywood and pouring the roof. Then removing the plywood when everything was set. I mightn't be going ahead with it at the moment though, there's a problem with the vault door. If it can be fixed, I'll go ahead with the build. If not, I'll have to wait to get another door.

DOCARCH

Another option for walls would be reinforced hollow block.