60" Bath Rough In Question - Please Help!

I inherited a somewhat gutted bathroom with a little work done in the home I just moved into. I want to buy a 60" soaking tub. This one:

https://www.us.kohler.com/us/Archer...ctDetail/Archer/425547.htm?_requestid=1361404

My question and potential problem is if I have enough space to do it. From cement board to cement board I have exactly 59". The home depot site says the assembled width of the bath tub is 60". I will be tiling the rest of the wall and it will be a bath/shower. How can I make the bath fit, is there any way?

Easy...start over. The TUB goes in FIRST, stud to stud. Then the cement board is installed, to slightly overlap the flange on the tub, but not touching the tub deck. It is sometimes necessary to shim the studs, so that the cement board will be plumb, not canted out over the flange.

So what you are saying is remove the cement board, there should be plenty of room for the 60" tub, install the tub, and then reinstall the cement board. No need to modify anything else? The tub I linked has a integrated tile flange which I believe remember hearing is important since I want tile to be layed on the walls.

First, cement will be poured to be level with the floor. Then the bathtub will be put in from there. Will this still be okay? The type of bathtub that I linked, is is the correct type for my setup? It includes an apron and from the manufacturer it says, "Thank you for your inquiry. This tub is not "free standing". It is a skirted tub that would be used in an alcove (would need framed walls on 3 sides) installation." I just don't want to order the tub after we figured out it can fit, but then realize it won't work in my setup. Please advise. thanks so much for the help guys!

You may need to remove much of the cbu to be able to get the new tub in there. Also, it likely calls for stringer(s) to support the long side, and may want them on the ends as well. Sometimes it's easier to notch the studs so the tiling flange then is flush with the studs when inserted. Otherwise, as Jombo mentioned, you may need to shim the studs out so you don't bow the bottom of the cbu. Depending on the size of the tile, you might get by ending it slightly above the tiling flange - you want more than 1/2 of the tile supported by the cbu. Also, install some vapor barrier (plastic sheeting or roofing felt) behind the cbu and lap the edge over the tiling flange. Cut it off after installing the cbu.

I don't see any water or drain roughed in yet

The drain is hidden and will have to be repositioned. The tub calls for this drain.
http://www.us.kohler.com/us/Archer%AE-bath-drain/productDetail/Non-Catalog/426252.htm

The ENTIRE wall system goes OVER the "tile flange", not just the tile. That is the FIRST 1 1/4" drain I have ever seen for a bathtub.

I just started shopping around for a new tub. I will be enlisting help for the install since I am new to diy but I plan to be involved because this is my first house and I want to learn diy skills. What I need to know in order to shop is the size of tub I need. Currently there is a one piece fiberglass shower/tub combo sitting in an alcove space that is 57" wall to wall. I want to install a drop-in tub (with a shower fixture, if that's important) and build a tile surround. Is it possible to put a 60" tub in this space? I don't understand all the technical terminology so please help me with a layman's answer. What is "cbu" anyway? Thanks.

The tub gets installed before the wall covering - it goes from stud to stud. The most common tub length is 60", while there are a few 54" tubs out there, what you have is a 60".