Cutting the base to size was easy. The instructions recommend scoring and snapping the base, as you would do with drywall, but with a product this costly I wanted to make sure I had a clean cut. So I cut first from the top, using a utility knife.
The weep drain was already in place. I checked that the floor was level, then nailed down a piece of 1/2-inch-thick Durock cement board in a bed of thinset.
I cut out the drain center and the bolt holes around the perimeter so that I could install the top half of the drain while the sealant set up.
I bolted the clamp ring onto the drain upside-down, flat-side down, so that the sealant and membrane fabric wouldn't squeeze up into the drainage grooves as the sealant set.
I measured and cut the 14-inch-wide perimeter membrane fabric, leaving enough for about a 4-inch overlap. Then, following the manufacturer's instructions, I prebent a 2-inch leg along one edge.
Next I installed the inside corner pieces, using two beads of caulk in continuous rings so that there would be absolutely nowhere for water to seep through.
After slitting the perimeter membrane to allow it to fold over the jamb, I squirted sealant onto the preformed corners.
I then measured the polystyrene curb cover that Noble had provided (this does not come with the ProBase kit), cut it to size with a utility knife.
I thinset the curb into place, making sure to get the mortar on both vertical legs as well as the top so that it would have good support.
I applied silicone sealant at the joint at each end of the threshold, per the instructions. Noblesealant 150 is incompatible with the polystyrene.
I then screwed the chrome plate into the drain assembly, positioned the plastic weep protector around it.
Finally, I filled the depression around the strainer with cement mortar — I use the bag form of Laticrete 3701.
Once the mortar in the base set up, I finished the job by installing Durock cement board on the walls.
I used cardboard to protect the shower base and also to create a gap at the bottom of the cement board.
I used mastic to adhere the Durock to the studs, making sure that the lowest nails in the cement board were no lower than the top inch of the membrane underneath.