Ditto! I totally want to thank you for making the time to write such a detailed, informative and *helpful* post. Your thoroughness is outstanding and totally puts me to shame. We just lifted up the old vinyl, cleaned the subfloor, laid out the radiant heat mats and then did the SLC atop it. Here and there a piece of the wire popped out of the SLC and i wondered what I was doing wrong. I was told "not to worry, the mastic / tile will cushion it and it'll end up level." Um, okay. But so far so good (we're doing the marble mini hex tiles). Anyway, so we were nowhere near as thorough as you and I'm kinda scared how we'll ultimately pay for that ... This post is a Must Read for all who plan on tiling. Bravo to you for writing it. And Thank You!

I was waiting until one of the pros on this forum answered. Speaking as an amateur, I would advise against using an orbital sander on your walls. You are likely to take the paper cover off and end up in worse shape than when you started. Skim coating is the answer, and hiring someone to do it is your best bet. I watched a guy do it, asked a lot of questions and learned how to do it. But someone who can do it well will do it with far less sanding and dust. If you are going to do this yourself, do some reading on skim coating. You want joint compound, not spackle. Spackle is for holes. And you want to sand by hand, not a machine.

Hi everyone! Thanks for the feedback. The tile definitely wasn't ceramic. When we tried to pull it up, it just crumbled into tiny pieces. We didn't want to deal with the potential of asbestos (we don't know when the flooring was installed but the house is old enough where it was a concern) so we decided to cover it. Maybe that wasn't the smartest idea but that's what we did so we can only move forward! The "little mountains" aren't huge but definitely hurt when you step on them and range from just a little bump to extremely noticeable. This might be a stupid question, but can we just ground the lumps down so they're equal to the rest of the floor? If we go that route, is there something we need to do to afterwards before putting down the tile? And can someone explain why peel and stick tile in the laundry room is a bad idea? I've read mixed reviews about that type of tile, but my personal experience has always been positive (though I've never experienced it in a laundry room). Thanks for all of the feedback! I really, REALLY appreciate it.

@Avanti Respectfully, you have missed part of my inquiry. Per my three questions posed in the original post, I am considering using self-leveling to address the slope in the floor before setting the tub. Therefore, again, have you used self-leveling over OSB, and if so, what brand did you explicitly use? I am seeking alternatives to afford myself multiple options. If the answer is “No”, that’s fine. Although, please let's stay on topic We're getting further away from my original post when I am also not requesting instructions (see original post) but rather recommendations for alternative products (explicit brand names) based on one own’s experience that are OSB-friendly - provided options seem limited. Note: As mentioned in my original post, the only lightweight OSB-compatible self-leveling that I could identify - whether at Home Depot or otherwise given I have searched brands sold at Big Box stores, smaller local or regional retailers, and online-based retailers - including brands like Laticrete - and even communicated with an array of manufacturing reps - is by Custom Building Products.