(resent due to my news server apparently dying yesterday)

A shipping container that was originally supposed to be a temporary
workshop is now going to be a permanent fixture, the only problem is
the place gets hot in the summer and freezing cold in
winter. The cold I can deal with by wearing a few more clothes or
eating a few pies, the heat is more of an issue. Fitting windows
isn't really an option for security reasons and the trickle vents that
are fitted are hopeless. Working with the doors open helps a bit but
there is next to no shade in the morning and only a bit late on in
the day so that on an 18 deg C sunny day it is hitting 50 deg C at
roof level internally by mid afternoon and I can feel the hot air on
the back of my throat at 2ft6 below the ceiling. Running a fan means
running a generator which is expensive and noisy.

So I'm thinking of lining it out with ply and filling the walls and
ceiling with some rockwool. Could I just batten it out with 2x2
fixed with a grab adhesive and then screw plywood to it or will I need
a vapour barrier behind the ply?

Would an air gap be a good idea next to the steel and if so how big
will I need?

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