THE RAIN IN MAINE

We have a small, nondescript house, what's called "a camp" on a pond in central Maine. It was built with a total and complete lack of any architectural elements whatsoever. In fact, it's incredible the building exists at all, given that it is 100% devoid of any style at all. Its existence is a mystery.
One feature of this structure is a totally inappropriate nearly flat roof made of nearly nothing. Old and featureless, the roof has virtually no slope to it. It's an invitation to collapse from snow, so far avoided, and leaks, which have not been avoided.
I asked, "what should I bring back from home today?" Among the list of "a few things", including drills, dacron, epoxy, bread, rice, brushes, chips and sundry, she said to bring the old, mostly empty can of roofing tar, the idea being to attack some of the leaks in the roof.
Had we brought the tar earlier in the week, when the weather was fine, it might have been of use. But with the skies opening up moments after I arrived, and the forecast predicting steady rain for more than a week, the opportunity to make use of its leak-preventing properties will be delayed until we're actually not here.
Ah well. I suppose a few leaks here and there are better than goveling on the roof with black goop that will get all over everything and won't actually do squat to prevent leaks.