On Site with ProBase

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.

I flipped it over and finished cutting from the back.

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.

The floor sheathing brought the surface flush with the drain flange.

I applied a double ring of Noblesealant 150 around the drain flange.

Sealant applied to the drain flange

After fine-tuning the fit of the base, I prepared to bond it to the floor.

I troweled out modified thinset with a 1/4-inch-by-3/8-inch square-notch trowel.

I set the base into place.

I firmly pressed the membrane into the sealant around the drain.

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.

Note that the bottom of the clamping ring is grooved to allow water to weep into the drain.

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.

I applied a double bead of sealant around the base to create a good bond.

I firmly bedded the 2-inch leg into the sealant, looking for a continuous line of squeeze-out.

Sealant squeezed out of the membrane joint

After sealing the overlap in the corner, I worked back around the perimeter with the caulk gun.

Additional sealant was used to thoroughly cover the joint between the wall membrane and the base.

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.

I pressed them into the corners, again looking for squeeze-out and tooling the edge with my finger.

The preformed outside corners were next, two per jamb, applied directly to the wood with sealant.

Again, I used plenty of sealant and tooled the squeeze-out.

After slitting the perimeter membrane to allow it to fold over the jamb, I squirted sealant onto the preformed corners.

I spread modified thinset over the exposed wood — back, top, and front.

Then I bedded the membrane onto the threshold with my trowel.

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 drive a few plastic-cap roofing nails on the outside of the curb.

I applied silicone sealant at the joint at each end of the threshold, per the instructions. Noblesealant 150 is incompatible with the polystyrene.

I let the sealant and thinset set up, then plugged the drain and performed a water test.

After covering the drain cap with duct tape to protect it, I marked the orientation with a pencil.

I then screwed the chrome plate into the drain assembly, positioned the plastic weep protector around it.

I adjusted it so that its orientation was correct.

I checking for correct tile height and slope with a level.

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.

Tiling was the final step.

The finished project

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