A correction, the waterproofing is a rubber plate extending from the lower edge of the socle to about ground level, not the upper edge. It would be quite ugly that way.

There's also probably a difference in weather patters between the south of Finland and Illinois. Rainfall is quite evenly distributed here. Heavy downpours here are probably not as heavy as in Midwest USA. Of course, you can have serious problems because of the local contours of the terrain here as well. And there is often flooding in river valleys in certain areas with very flat terrain.