door hanging

I want to build this small brick storage space in my garden, about 2m long, 1.4m wide, 1m high (the plan here isn't finalized). Probably add a simple fixed down wood and felt flat roof. I might add a metal door to the open side. Im wondering if this plan is strong enough - its small and short so...

Hi all, one of my internal doors is not hung properly but I don't know how to correct it. The problem is that won't stay at 90 deg, it keeps closing half way. It's a door between our lounge and a lobby which I'd like to keep open, but it just swings back to half way! It's a glazed 15 panel door...