Regarding storing money in a hut, which is at risk of fire, this seems to be in conflict with Artscroll's note 30 on their page 42A3.
The Gemara seems to be saying that even if the fire risk did not contribute to the theft risk, that the custodian is liable due to being negligent in protecting it from fire. And the footnote seems to say that this is only if it was contributory.
Perhaps the Gemara is saying that there is a presumption that if he is negligent in any way, that he was also negligent in other ways, but that this presumption can be overcome if he shows that he was not negligent in any way which contributed to the actual loss?
And similarly, if the item he stored was metal coins that are not subject to fire risk, unlike paper money, that a hut is a fine place to store them?
How about if the item owner lived in a hut, and so did the custodian, is this sufficient that a hut is a suitable place?
And finally if he stored the money within a fire safe that itself was within a hut, if the fire safe if in plain site would be considered sufficiently guarded, could the presence of a hut over it cause the custodian to be considered negligent?
Dear Robert,
Artscroll's note 30 on 42a3 correctly explains the Gemara. Accountability in a case of "Starting with P'shia and ending in O'nes" is only if "the mishap was made possible by the act of negligence" (he was not negligent concerning the mishap - it remains O'nes - but he did bring about its occurrence). However, if the mishap would have happened anyway he is not responsible.
So metal coins can be stored in a hut and if the money is within a fire safe he is not negligent even if a hut is over it.
You also asked if a hut is sufficient when the owner and custodian live in a hut. A prominent Rav assumed the custodian to be still responsible unless the owner has used before custodians who guard inefficiently, thus showing that he does not demand a full watching. (If this really happens ask a Rav).
All the best,
Reuven Weiner