Our company not only installs trim and cabinetry but also focuses on bathroom and kitchen remodels ranging from cosmetic changes to complete renovations. Over the course of 15 years, we have installed $15,000 showers with full tile surrounds, mud floors, and copper pans, as well as $1,500, three-piece acrylic tub units. In the same time frame, a lot of new products have come onto the market.
On a recent project, we used one of those products. Instead of going with a traditional acrylic- or mud-floor tile shower, the owner opted for a cast shower floor. We selected one produced by Castico and ordered it through Home Depot.
We had several reasons for choosing this base. For starters, Castico offers multiple beautiful finishes and colors, including for the drain lid, which is provided with the unit. Bases are available with a right-side, left-side, or center drain. There are two texture options, both of which provide a slip-resistant walkable area. Budget was important on this project, and so the traditional approach using a plumber’s pan, mud floor, and tile install was cost prohibitive; the Castico shower floor eliminates not only certain materials but also some labor. The caveat is that the tolerances are tight for the area where it will be installed.
We started by demoing out the entire shower area down to the framework. Here’s where it got involved: Installation of a cast shower floor requires the walls to be absolutely plumb and square. On a 100-year-old house, that can be a challenge. We removed a lot of existing framing and squared up the corners of the shower area by moving and adding new wall plates. From there, we plumbed up the walls with new framing material. Next came the subfloor. The existing floor had a sag of about 5/8 inch in the center. We could have added a self-leveler to the floor but we preferred to remove the existing subfloor and sister new floor joists to the existing ones to level the floor out completely. We then installed Georgia Pacific Denshield 4x8 boards, glued and fastened to the framing using 1 1/2‑inch stainless steel screws. Denshield is a waterproof substrate for tile, but the seams still need waterproof mesh and thinset.
Once that was done, we created a template using 1/4-inch lauan and hot glue and transposed it to the shower floor. Using a hand-held tile saw with a water spout, we cut the shower floor to size. Cutting it was a breeze; you just have to remember to take it slow and let the saw do the work.
With the floor base cut to size, we applied waterproofing flanges (provided by the manufacturer) to the edges of the base with screws (also provided). The directions provided by Castico offer two options for installing the shower floor: Use subfloor glue, or use thinset mortar. We chose thinset, feeling that option would provide total support to the base, and we opted for the flexible version to allow some separation between the Castico floor and the existing framing. We mixed up a batch, applying it directly to the subfloor. Next, we back-buttered the shower floor and carefully installed it. (It took two people.)
We gave it 24 hours to set before sealing the flange with a waterproof silicone. Again, we allowed that to cure for 24 hours before starting the tile. Deciding to allow that time to cure was our choice. The floor was installed after the waterproof substrate was installed—contrary to an acrylic shower base going in first and the substrate being applied to the walls after. That was per the manufacturer’s directions. Tiling the walls was no different from usual, and once they were grouted, we applied a seal around the shower floor and the tile using a waterproof caulk.
Overall, we were impressed with the Castico shower floor. The unit cost about $650—well worth it, in my opinion. Compared with previous jobs of similar size and scope, it allowed us to save about $300 to $400 on labor and material. The installation of the shower floor did have a slight learning curve, but we will definitely use it again in the future.
