Shower process
I have built a number of showers the old fashion way using a sloped mortar bed, PVC shower pan and mortar bed. I am about to start a remodel and want to use Hydroban membrane and want to make sure I am on the right track. The shower is on a slab foundation.
clean existing concrete slab.
Install concrete wall board all the way to the floor.
tape and seal joints per wall board manufacturers recommendations
install FloFX drain approx. 1" above the slab.
lay modified thinset on concrete slab
lay dry pack mixture over wet thinset sloped 1/4" per foot from top edge of FloFX drain out to wall board
once dry, paint two coats of Hydroban over floor and walls
Am I missing anything?
Also, I cannot install a curbless shower but want to have a minimal height curb. If the drypack is 1" thick at the drain, the curb could be approx. 1-1/2" (plus tile thickness). Any issues with this plan?
Your plan looks spot on. A word of caution: Make sure your mortar bed is completely dry before you apply the Hydro Ban. I let mine dry for 5 days before I applied the hydro ban and because it was cold in my shop it still was not dry enough even though it turned light gray. Everything looked good but when I flood tested it, after 12 hrs bubbles formed in the Hydro Ban as the water vapor in the mortar bed was trying to escape. I redid it, this time letting it dry for 2 weeks and it worked good. A good way to test if there is still moisture in the mortar bed is to place a piece of plastic on it and let it sit overnight. If you remove it and there is a dark patch where the plastic was, there is still moisture evaporating. While it is not as big of a deal for a DIY to wait for the mortar to completely dry, this is the ultimate reason why we choose sheet membrane over liquid on the pans for our jobs. We can literally float the pan and cover it in membrane the same day if we need to. I have a tub of Hydro Ban quick cure that I will be experimenting with soon!