My grandma eats sweets including homemade pies with 1-2 c sugar per pie, loves sweets in general, eats too many fried foods for my taste, doesn’t eat paint chips, bathes in a porcelain tub, and was JUST moved to a nursing facility this year since she’s losing her mobility (mind is still intact) and in another month she will be celebrating her 100th birthday. You don’t have to live in a bubble to live a long life. Much of your life expectancy is predetermined in large part by genetics. Use common sense and don’t lick the bathtub.

You are in a pickle here I think. If the wooden window is getting wet or has gotten wet in the past the job of waterproofing it will be very hard. Properly waterproofing a window is tricky and requires a little care and some speciality waterproofing products. Cutting the window's jamb level with the existing backer board is not a hard thing to do and a good first step. I might suggest you install some kerdi band to the wooden sides of the window with Kerdi Fix as an adhesive. Before any waterproofing steps are taken the old window should be sanded and check for damage. A product called "Wood Petrifier" could be used to repair soft spots on your window. An oil based priner and good quality marine paint for the window. Ideally you can tile the inside portions of the window jamb and have a sloped window sill. As Stacey mentions pictures go a long way to providing options. What was used as a backer board in the shower? Was any waterproofing measure used in the wet zone? If you like email me your pictures and I can upload them for you if your having troubles doing so. jfrwhipple@gmail.com

Tonight DH and I discussed how we want the contractor to finish the tub and walk in closet bumpout. And to what degree we want it completed. DH is an itch about doing things so-so, therefore it will be better to add the tiles ourselves, and do the painting as well. BUT, the electrical, the plumbing, the windows, the removal of the old pair of windows in the bedroom to allow entry into the new closet, that will be framed and cut by the contractor. Also, drywall and taped, but we will finish with a skim of plaster--or so DH thinks. I am ready to leave the closet drywall plain. I am fed UP with DUST. In the tub bumpout, I've decided I want it all beadboard...roof and walls. I think there is a synthetic beadboard mfg by a company with a name beginning with "A"...am I right? That would be very very water proof or moisture resistant. Of course the contractor will do the foundation, the framing, the roof as well. Our windows will be up high near the little rafter "tails" that stick out all around the house. The clerestory "lights" will be NON opening, and made of Lexan. DH says that if you make them less than 24 inches (they will be about 16) you do not have to allow for expansion/contraction of the Lexan. So each small panel can be caulked in and screwed down. That will give us natural light all along our northern exposure, and require no window treatments. I want these Lexan panels in the walkin closet also. I already have the wire closet kit to make high and low hanging racks and such.In fact, I might even get the contractor to install them for me. The top shelf rack will come about the height of the window bottoms. The roofline will just extend at its current angle, and we will lose a little closet height near the outer new wall...but not enough to create a problem. Having the "lights" up high will really take advantage of ambient natural light coming from the north, which is true and consistent all year long, winter and summer. For closet doors, I plan to get two pairs of bifold with frosted glass in the top panels, and louvered fixed shutters in the bottom panels. They can be installed later by us, because the brand I want is special order from Lowes. I also already have the tub fixtures/plumbing stuff ready to be installed. And the two short sconces and one longer double ended sconce for the sink, and the towel bars and racks and ONE grab bar. I plan on more of these grab bars, and will ask the contractor to place a lot of blocking in the walls while they are open. I am so excited. I've tried not to get my hopes up, this might not work out, but OH BOY I"M READY TO TAKE A TUB BATH. If the man is a professional, this job should not take very long, should it?

As Nancy in Mich said, tubs should be installed on a wet mortar bed to support the entire bottom of a tub. The OP says they had special access cut in the closet wall order "to do that mortar"...but that does not sound like a thick mortar bed, which is what is needed. The mortar bed would be put down under the tub before it's installed, which after removing the old tub or shower base should not be a challenge. Some of the comments mention that their tub cracked even though sitting "directly on the concrete basement floor", so that would be what cause the problem in that situation. Tubs are heavy, tubs filled with water are heavier, tubs filled with water and a person are the heaviest of all.