I'm becoming a little more educated. I now know the difference between porcelain and ceramic tile, and sanded vs. nonsanded grout. Now we just need to find a supplier with a showroom....the local big box home improvement stores haven't carried a tile that called to us.
The floor joists are on 16" centers, and they are 2 x 10's. The native lumber was cut on site, so they are a full 2" by 10". I helped saw them almost 30 years ago. They span 14', and are covered by 5/8" subfloor.