Hi Kate - I had a similar problem with an office that I just moved out of - but ours leaked when they turned the sprinklers on not just when it rained!

In our case there were seams in the foundation which had separated over the years - to fix it we put a sealant over the seams - it worked and no more water wicked up into the office (I only wish I had done it a few years before)

The stuff we used started as a powder, mixed with water and then aapplied - it was the color of cement and was meant to seal against water (I obviously don't recall the name of the stuff) - we got it at a local home improvement store.

Canie