What primer or sealer goes on drywall before acrylic shower walls?

Before an Ella acrylic or SMC wall kit goes up, the wall behind it should be moisture-resistant drywall, marine-grade plywood or cement board, sealed with a water-based or oil-based primer and sealer. Use two coats on plaster, on concrete, or on a wall that has just had wallpaper removed. The sealer prepares the surface, and the panels themselves are then set with 100 percent silicone, which is the one product every Ella wall family shares, as explained in Which Adhesive or Caulk Do Ella Acrylic Wall Panel Kits Require?.

Why the Wall Is Sealed Before a Glued Panel

Every Ella wall kit is glued to the wall rather than screwed or nailed, so the wall itself is part of the system. The acrylic 3-panel kit is glued only, dry-fitted first and then braced or taped for 24 hours while the silicone cures. The SMC 12-piece kit is set on a continuous perimeter bead of 100 percent silicone with vertical beads every 8 to 12 inches. Both methods depend on a surface that is sound, clean, dry and sealed, because an unsealed spot is where water can get behind the panel if a seam ever opens. That is why a completely waterproof substrate is recommended in a wet area, and why a panel must never be installed over a damaged wall.

Two other conditions apply to the wall before any sealer or silicone goes on. The walls need to be plumb and square within 1/8 inch, and the panels should go up with the room above 65 degrees. The SMC installation steps repeat the first point: the back-to-side corner has to be plumb and square before the bottom row is dry-fitted. Local building codes for shower and tub enclosures still govern the job, so your contractor should confirm the wall build-up for your jurisdiction.

Approved Substrates and What Goes on Each

• Moisture-resistant drywall, marine-grade plywood or cement board. These are the substrates named for an Ella wall kit. Seal them with a water-based or oil-based primer and sealer before the panels go up.
• Plaster or concrete. Two coats of primer and sealer.
• A wall that had wallpaper. Remove the paper, then apply two coats of primer and sealer.
• Existing walls under the SMC kit. The SMC installation steps allow drywall, cement board or an existing wall, cleaned, dried and patched, with the corner checked for plumb and square.
• Cultured marble surrounds. These glue over drywall, plaster, painted walls, Durock or existing tile, the widest substrate list of any Ella wall product.
• Tongue and groove PVC tiles. These go over a clean new or existing surface that qualifies as an approved substrate, after the cartons have acclimated in the bathroom for 24 hours.

No brand of primer, sealer or silicone is named in Ella's published documents, so the answer is a type rather than a product. If you are unsure whether your wall qualifies, describe it to the team at (800) 480-6850 before the panels are cut rather than after.

Preparing the Wall, Step by Step

1. Strip any wallpaper, patch holes, and let the wall dry. Replace any damaged section rather than paneling over it.
2. Check that the back-to-side corner is plumb and square within 1/8 inch, and correct it before sealing.
3. Apply the water-based or oil-based primer and sealer, with two coats on plaster, concrete or a stripped wall, and let it dry before dry-fitting.
4. If your tub uses the glue-up tile flange, position it now. The strip is about 5 inches tall and overlaps the tub edge by about 2 inches, the tub edge is cleaned with the alcohol tissues in the kit, and 100 percent silicone bonds it. The flange video on this page shows the strip position being marked on the walls with the tub temporarily in its working position, so the lines are drawn before anything is bonded.
5. For the SMC kit, mark the 96 inch height and confirm panel sizes. For the acrylic 3-panel kit, store the panels flat and dry-fit before any silicone.
6. Bring the room above 65 degrees and keep it there while the silicone cures.

The full sequence for each wall family, including the row-by-row order for the SMC kit, is in Installing the SMC 12-Piece Wall Kit, Acrylic Tub Surrounds, the 3-Panel Kit, Tongue-and-Groove Wall Tiles and Palisade Vinyl Tiles.

Finishing the Inside Corners

The inside corner is handled differently by each kit, and this is where most questions about Ella wall panels end up.

• SMC 12-piece kit. The side panel overlaps the back panel's flange at the inside corner, so the corner is built into the panels. Once all four rows are up, finish the inside corners with white caulk, fill the perimeter and top-row gaps, inspect every seam and allow the recommended cure before the first shower.
• Acrylic 3-panel kit. The 60 inch back panel and two 40 inch side panels are cut to fit, and the edges are finished with molding, which is not included, or with caulk. After the 24 hour brace, every joint in the wet area is sealed with silicone.
• Tongue and groove PVC tiles. A thin bead of silicone goes at every joint before the tile snaps into the one before it, and every seam in a wet area is sealed.

Where each bead goes and how the tub edge is sealed is covered in What should I use to seal shower walls and caulk the tub edge?, and the PVC tile method on its own is in How do you install and seal tongue and groove PVC shower wall tiles?.

Which Silicone or Adhesive to Put on the List

For the acrylic and SMC kits, the shopping list is 100 percent silicone plus clamps, braces or painter's tape to hold the panels still while it cures. Screws, nails and a separate panel adhesive do not belong on an Ella acrylic or SMC wall. The PVC tiles are the exception, taking adhesive on the back of each tile plus the silicone bead at the joint, and the cultured marble surrounds are glued with an adhesive whose type is not listed. Both the SMC panels and the PVC tiles use a tongue and groove interlock, so name the exact product when you call, or the answer may describe the wrong one. The adhesive and silicone rules for every family are in one table in Which Silicone or Adhesive Do Ella SMC and Acrylic Wall Kits Use?.

Watch: Installing a Glue-Up Tile Flange: Step-by-Step | Ella’s Bubbles with chapters and a full transcript.

Related Guides

• Acrylic 6-Piece Wall Panel Kit: Size, Shelves, Thickness and How It Compares to the 3-Piece Surround and SMC Panels
• How do you install a shower wall panel kit from Ella's Bubbles?
• Wall Panels and Surrounds for Walk-In Tubs: Acrylic 3-Panel Kits, Cultured Marble, and PVC Tiles

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