word of advice, DO NOT do this in a snowy/sub-zero region. I have a friend who has to replace some of the tiles here in Indiana every single year. They'll crack in sub-zero temps and leak like a sieve. They're best suited for warmer, moister climates. I'm not sure how your winters are in Iowa normally, but we routinely get around zero a few times a year and sometimes colder.
Thanks, good to know. I prefer archetectual fibreglass but the wife wants something closer to the 100 year old clay tile. Most contractors won't install or do any repairs to the clay or the fancy metal stuff.