Storing tins in a damp environment

[Straight Shooter]

In my case i have had lots of fails...mostly with tinned goods , i have stored these indoors on a shelved system ...the shelves made from 2" x 1" batten to allow air through and ventilate ...i have cut a vent to the outside and temperature has been steady..and still failed ..... i have used insulation to try and counter the damage (RUST) improvement but still not right , so i moved the lot into a back of an old lorry body ...i insulated it all walls and floor back last year , this faces north so i thought this would do better keeping the prepps cooler , again the shelve system this time was the same, i opened up this week to check ....not at all good tins had signs of condensation label damage and some leaking (fruit tins and tomato tins ) were the worst ....all dried stores in mylar bags have done the best no signs at all of damage....all these stores are in plastic barrels and sealed ranging from 10 k to 60 k so this week i have loaded some new 30 k kegs with new tin stocks to see if this method is any better....very relevant post MB....i would be very interested to know more of the circumstances of how you manage to get your success ....i must be doing something wrong....can you describe your back room ....heat ...cold...insulation...position.