Iím preparing a bathroom for tile installation and Iíve been removing a 3/8 layer of glued down particle board that had vinyl floor attached to it. The particle board is attached to ĺĒ plywood. It looks like the cast iron tub is sitting on the particle board. So basically Iíve removed the particle board up to the point of where it goes under the lip where the tub meets the floor. I was hoping the particle board just butted up to the tub, but it goes under the tub. My question is what is the best way to deal with this? Should I just clean up the edge a much as possible and when I lay 1/4 hardibacker just run it up to meet with the rough particle board edge along the length of the tub?
That should work...have you checked the stiffness of the subflooring to ensure it is strong enough for tile? You shouldn't just assume it is. Normally, 3/4" plywood is near the minimum, and without knowing the depth of the joists, their spacing, and the longest unsupported length, you should not assume it is. It doesn't matter how big or small the room is, it is the design of the structure under it, on the entire floor that is important. If you check out www.johnbridge.com on the top of the forum's menu bar is a link to "deflecto" which will allow you to check, assuming you know the makeup of the floor structure. You need L/360 MINIMUM for ceramic, and L/720 for stone tile. Note, Hardi backer (and any brand of cbu) is NOT considered structural, so on a floor, 1/4" is fine. Tiling questions will get alot more action on John's site.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013