Thanks Bill V. Very helpful. The spacing of the joist is 21" OC. The length of the joist are about 10', free span, but possibly 12' total taking into account the ends that sit on the plate. I had meant to ask on my post if there would be a tile size limitation such as 12x12 or 16x16. I was thinking of doing a small Versailles pattern where the largest is probably around 16x16. As I mentioned, this part of the house is joisted differently than the rest of the house, I think they where saving some lumber;) My DIA (dear inlaw ancestors) had this bathroom addition put on over the crawl space after they moved this small house from town and onto the farm. The rest of the house is sitting over a regular basement. My late DFIL and his sister hand dug the basement when they were teens. They used the horse team and a slip. DH remembers his dad talking about how hard the soil was. His DD said when the slip hit the hard soil and bucked, he'd end up on the backs of the horses. He must have been standing on the slip.

Don, you're making me faint with the removing the floor prospect! But my husband says you're probably right;(. Though he does think that we can get in there and do this job without the tear out. He has done a lot of stuff over the years being a farmer, jack of all trades, and in a past life an aerospace engineer (the math!). We have a 20 year old son who can crawl! So that space will be accessible. But I am listening to your caution of "You would be more inclined to do all the work properly" if the floor was taken out and area exposed. I added my link to the joist info request on the Remodeling Forum. Here is a link that might be useful: Adding Joist to Existing & Intact Floor

I just had a similar dilemma in my master bath. I ended up tiling to eye level. Lower just didn't look right. Much of this depends on the vanity, mirror, and light fixtures around the sink area. I would not do the 3 foot high around sink then change to eye level border around tub. I would do the vanity area with border at eye level and go all the way around, including the wing wall and tub area. It just seems like you would then be tiling to protect the walls from water splash. Which makes sense.

cabinetfanatic is right on. I didn't want to crawl under the house and follow all the wires. So what I did was remove the wall phone plate and connected matching wires together with B wire connectors (easy peasey to use) that I bought on amazon. (they were the same ones that were already used on some of the wires in the group of 4 sets (for 4 extensions throughout the house)...this is a 1970 house with spaghetti phone wires! Even though the wires are low voltage I wanted them secure to avoid any problems. Then I patched it using a patch kit. I made myself a note in my "info about my house" folder with photo of the open hole and wires for future homebuyer to use the connection if they need to dig it out. They might need to review that wiring if the extensions aren't working some day. Just as a courtesy. Our previous owners gave me the idea of a saving info like that.