Making some progress...

I finally put down the electric radiant heat for the bathroom that's been sitting in the box for over a year. It was relatively painless and really the main thing holding me back was fear of the unknown.

On top of a 3/4" plywood subfloor I used 1/4" USG Fiberock under the heating mat and 1/2" GP Dens Shield at the sink and tiolet areas. I used the Dens Shield because I had left over pieces from the tub wall installation. I poured 2 layers of self-leveling cement (SLC) on top of the heating mat (1st pour was 1/4" over the Fiberock, 2nd pour was 1/8" over entire floor). I did it in two pours because I could, realistically, mix only one 50lb bag of SLC at a time.

I used the tips that I got from one project closer and things went pretty smooth. The 2nd pour looked great this morning and I'm ready to tackle the floor tiles! At least we've had them for less than a year.

Lessons learned:

1) If you think you need to glue the heating mat down in more places, you probably should. In the 1st pour some areas of the mat got pulled up as I was spreading and then the SLC got under the mat. I had to spend a little more time pushing the mat back down. A little nerve wracking when you only have a 10 min working time for the SLC.

2) Don't pour too much SLC in one area to make the 5 gallon bucket mix lighter. A 50 lb bag + water is pretty heavy, plus handling it and being careful while walking on the radiant heat mat isn't fun. I ended up pouring a lot in one area because it was heavy and cumbersome then spent most of the time spreading the SLC from that area to the rest of the floor.

3) Make sure you have a plan for spreading the SLC. I had originally thought I could pour the SLC and spread from the doorway. I never would have been able to reach all areas from there and ended up spreading from the tub and jumping out of the bathroom after.