Shower Wall Panel Installation Guide

These instructions apply to CASTICO alcove shower wall panel sets (2, 3, and 4 panel). For corner kits, see Corner Shower Wall Installation Guide.

Read the full guide before starting. These instructions are not all-inclusive, and images in the printed guide are for illustration only. We strongly recommend a professional installer if you have any doubts about the process.

Available sets

All panels are 84" tall and 1/2" thick.

Set	Size	Side walls (A & D)	Back walls (B & C)
4 panel	34" x 48" x 84"	33 5/16" (2 pcs)	23 7/8" (2 pcs)
4 panel	32" x 60" x 84"	31 5/16" (2 pcs)	29 7/8" (2 pcs)
4 panel	36" x 60" x 84"	35 5/16" (2 pcs)	29 7/8" (2 pcs)
4 panel	36" x 72" x 84"	35 5/16" (2 pcs)	35 13/16" (2 pcs)
3 panel	36" x 36" x 84"	35 5/16" (2 pcs)	35 13/16" (1 pc, B/C)
2 panel	60" x 84"	None	29 7/8" (2 pcs)
2 panel	72" x 84"	None	35 13/16" (2 pcs)

Before installation

Review the complete guide before attempting to install.
Inspect all products on delivery. Report any damage, defects, or missing items to CASTICO Customer Care within 5 days of receiving the order.
Confirm the shower base fits the intended location, including the drain location.
Observe local building and plumbing codes.
Prepare, level, and waterproof the shower area.
Do not begin installation if any component is damaged, has a manufacturing issue, or is missing.
Indoor use only. Do not install in direct sunlight.

Required for installation (not included)

Safety goggles, measuring tape, utility knife, leveling tools, putty knife, 1/4"–1/2" notch trowel, rubber mallet, construction adhesive (polyurethane) or polymer-modified thinset mortar, bath silicone sealant, hole saws, #1 Phillips drill bit, power tools (drill, tile saw or circular saw), suction cups, painter's tape, and cargo bars or 2x4s for bracing.

Warning: Standard (unmodified) thinset mortar is not suitable for this product. Use only adhesives approved for non-porous stone surfaces, such as polyurethane construction adhesive or polymer-modified thinset. Follow the adhesive manufacturer's instructions for substrate prep, application, coverage, open time, working time, and curing. Failure to do so can cause poor bond strength, loss of adhesion, or the panel uncoupling from the wall, and may void the warranty.

See Recommended Installation Products & Accessories for approved products.

Step 1: Shower space preparation

Install additional stud supports for accessories such as grab bars, shower seats, and shower doors.
Substrate: moisture-resistant backer board or moisture-resistant drywall must be installed and level, with all seams sealed with waterproof membrane.
Shower floor: the CASTICO base or other shower floor must be fully installed and all adhesives fully cured before starting the walls.
Cover the base or shower floor with thick cardboard before starting.

Step 2: Wall orientation and pattern alignment

Identify each panel and its direction. Panel letters and directional arrows are on the back of each panel.
Lay each panel decor side up on a flat, level surface and arrange them alphabetically to check the pattern.
Pattern: patterns flow continuously left to right across all panels. Installing panels out of order or upside down breaks the pattern.
Pattern alignment: may vary up to 1/16" vertically and horizontally and may need minor shimming. If misalignment exceeds 1/16", contact Customer Care before installing.
Panel flex: panels may flex up to 1/8" when laid flat. Bracing (Step 8) ensures full contact with the substrate. If flex exceeds 1/8", contact Customer Care before installing.
Wall installation is a continuous process. Make sure you have enough time and materials to finish all panels in one session so the pattern stays aligned.

Step 3: Trimming guidelines

Rest each panel decor side up on a cutting table or flat surface that fully supports the whole panel.
Use a wet saw or circular saw with a diamond tile blade, or a circular saw with a fine-tooth carbide blade.
Apply painter's tape over the cut line, decor side up, to prevent chipping.
To minimize pattern interruption, trim only interior corner edges that will not be exposed.
Safety equipment is strongly recommended.

Step 4: Back wall prep and dry fit

Measure the back wall area and the back panels (B and C, or B/C) to confirm the total width fits.
If trimming is needed, trim only the outer edges that will sit in the corners (the edge of B toward the left wall and the edge of C toward the right wall).
Dry-fit the back panels. Repeat measuring and trimming if needed.

Step 5: Back wall installation

Clean the wall area and panels of dust and debris.
Apply adhesive to panel B (or B/C) and to the left side of the back wall, only where the panel will go. Do not apply adhesive or thinset to the waterproofing flange.
- Construction adhesive: continuous 3/4" diameter beads in straight lines, 4" apart. The first and last beads must be 1" from the panel edges.
- Thinset: trowel onto the wall area and the back of the panel.
With arrows pointing up, press panel B against the wall with even pressure. Check level across the panel and edges and adjust with a rubber mallet. If the kit has only one back wall (B/C), go to Step 6.
Apply adhesive to panel C and to the right side of the back wall.
With arrows pointing up, press panel C into place. Slide and shim B or C as needed to align the pattern, then check level and adjust with the mallet. If the kit has only back walls (B and C), go to Step 8.
Clean excess adhesive from all panels before it dries.

Step 6: Side wall prep and dry fit

Measure each side wall area (A and D), starting from the face of the back wall panels.
If trimming is needed, trim only the edges that will face the interior corners.
Mark and cut the shower head and valve openings on the correct panel. Fully support the panel during drilling, use a hole saw, apply painter's tape over the area, and cut decor side up. Account for wall thickness when measuring hole locations.
Dry-fit the side panels. Repeat if more trimming is needed.

Step 7: Side wall installation

Clean the wall area and panels. Apply adhesive to panel A and the left side wall, using the same bead or trowel pattern as Step 5. Do not apply adhesive to the waterproofing flange.
With arrows pointing up, press panel A against the wall, installing it against panel B. Slide and shim to align the pattern, check level, and adjust with the mallet.
Repeat for panel D on the right side wall, installing it against panel C.
Clean excess adhesive from all panels before it dries.

Step 8: Bracing and finishing

Use cargo bars or 2x4 lumber to press each panel against the wall while the adhesive cures. Brace the back wall and each side wall against the adjacent wall. Leave braces in place for the full curing time of the adhesive. Removing them early can cause panels to shift or loosen.
Do not over-brace. Excessive pressure can deform or damage the room walls or the panels. Check with a level and use only enough pressure to hold the panels in place.
Apply 100% bath silicone to all wall seams: panel joints, inside corners, and where the walls meet the base. Painter's tape 1/8" from the edge helps keep the bead clean.
Install the shower head, valve, and accessories. All accessories must be anchored to studs. Seal any perforations in the panels with silicone.
Do not use the shower until the silicone has fully cured per the manufacturer's instructions. Water can prevent silicone from curing.

Care and maintenance

Clean with neutral soap, a foaming shower and tile cleaner, or a calcium, lime and rust remover, using a cotton knit rag or plastic fiber scrub brush. A water-based impregnator sealer is recommended for long-term care. Do not use solvents, abrasive products, direct household bleach, or scouring tools.

Support

For questions or to report an issue, contact CASTICO Customer Care at (844) 364-2502 or contact@castico-tx.com. Installation videos are available at castico-tx.com/support.