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Installing Multi-Piece Gel Coat Showers: Barrier-Free Roll-In (BF) and Low-Threshold (SH) Units

Updated September 2026

Installing a multi-piece gel coat shower from Ella's Bubbles follows one of two manuals. Barrier-free roll-in (BF) units need a framing pocket 1/4 inch larger than the shower, a floor within 1/8 inch of level, a 6 inch drain core with a 10 x 10 x 1/2 inch recess, and two installers. Low-threshold (SH) units rest on wood support wedges that are mandatory, are joined with silicone at every seam, fastened with 6d galvanized screws every 8 inches on center, and leak-tested before the wallboard goes on. Receiving, the dam and the general base overview are covered in installing shower bases, the flexible dam and shower walls; the three-piece molded-seat shower and the one-piece AcrylX stall are covered separately.

Which Units These Manuals Cover

Numbered diagram of a five-piece Ella shower kit showing four wall panels and the seated base
A five-piece kit: four wall panels indexed to the base by the slot-and-pin system.

Barrier-free roll-in: 3838 BF 4P, 4836 BF 4P, 5050 BF 4P, 5430 BF 4P, 6030 BF 5P, 6033 BF 5P, 6036 BF 5P, 6048 BF 5P, 6060 BF 3P and 5P, 6232 BF 5P and 6238 BF 5P, with center or right/left drains. The framing table in the manual gives width, drain offset and depth for each; for example the center-drain 6033 frames at 60 1/4 inches wide by 33 5/8 inches deep, and the center-drain 6036 at 60 1/4 by 37 1/4.

Low-threshold gel coat: 3648 SH 1S 3P, 4836 SH 4P, 6030 SH 5P, 6032 SH 1S 3P and 6033 SH 5P, in three, four and five-piece configurations.

Handling Rules for Every Gel Coat Unit

  • The back of a fiberglass unit is not waterproof. Store it so water drains off; a soaked back can bulge the gel coat.
  • Most damage comes from impact to the back. Never drag or drop the unit, not even an inch, or stress cracks follow. Carry it with two people or a two-wheel dolly.
  • Keep cardboard or a drop cloth on the floor and seat while you work, and never clean gel coat with metal tools or razor blades.
  • Inspect on delivery and report damage within 48 hours following the freight damage steps; a damaged unit must never be installed.

Barrier-Free Roll-In Units

This tutorial follows a barrier-free five-piece unit from receiving inspection through the finished stall: checking the pocket for square, plumb and level, inspecting the subfloor, dry fitting and marking the threshold line, setting the drain, bedding the pan in adhesive, bracing it while the adhesive cures, and hanging the wall panels from the front on the pin-and-slot system. Pair it with these manual points:

  1. Frame the pocket to the diagram, which is 1/4 inch over the shower size for maneuvering; closer is allowed if 1/4 inch is unreasonable. Doubling the front studs adds strength. The design allows a 1/8 inch gap at the seams.
  2. The floor must be flat and level; anything over 1/8 inch out of level will prevent a successful installation. Float it with leveling compound and let it cure before proceeding.
  3. Provide a 6 inch core for the drain pipe and a 10 x 10 x 1/2 inch deep recess in the subfloor around it to assure drainage; the core is blocked when the area is filled with thin-set.
  4. Plan the control valve: on a two-piece back wall keep the valve clear of the seam and mounting flange.
  5. Do a full dry fit (minimal screws, no silicone or adhesive) through the wall steps first. Check every section against a straight edge; shipping can bow a panel slightly and it must be pressed back straight.
  6. Bed the pan: trowel solid wood flooring adhesive or 100 percent silicone over the entire pan contact area with a 1/2 inch notched trowel, fill the drain box with non-shrink thin-set (not above the floor line), rotate the pan into place, walk it into the adhesive and screw the flange to the studs with pan-head screws, snug but not tight. Adhesive working life is roughly an hour, so continue straight through the remaining steps.
  7. Before the adhesive cures, confirm the ledges are level and that the floor slopes to the drain in every direction with no humps or dips.
  8. Set the back wall first, then the side walls, indexed by the slot-and-pin system and pushed tight before fastening. Complete the valve and supply connections while the valve wall is still off; this is the last access to the plumbing. Two persons are required.
  9. The collapsible dam that ships with roll-in bases has its own instructions in the shower base and dam article.

Low-Threshold (SH) Units

The tutorial opens with receiving and inspection, then shows the dry assembly in a clean open space (correct panels, correct drain location, no damage, panels align), the pocket checked with a plumb bob, the base slid in on PVC rails, temporarily leveled and screwed at a center stud, a threshold line marked, the 2 inch no-caulk drain set in putty, and the base set permanently on silicone beads with the drain aligned. The manual steps for the low-threshold units:

  1. Locate the provided wood shims under the back edge of the base. It is mandatory that these wedges are in place and in proper contact with both the unit and the subfloor; they give the base its structural support.
  2. Install the drain with a bead of 100 percent silicone around the opening. Measure, mark and cut the valve and shower head holes with 1/4 inch pilot holes and a hole saw.
  3. Silicone every joint. Set the base, level it in two directions on the apron and the top of the wall, fill any gap under the apron with solid material, and fasten to each stud with 6d galvanized screws through the flanges.
  4. Run a continuous bead of silicone along the base between the edge and the fastener holes and up the vertical seams. Set the walls on the pins: on three-piece units the left wall then the right; on four-piece units the back wall first, then the left and right, with the wet wall last. Press the seams tight and wipe excess before it cures.
  5. Fasten the wall assembly every 8 inches on center along the vertical flanges and to each stud along the top.
  6. Connect supply and drain lines, strap them, install trim, and check for leaks before installing wallboard and closing off plumbing access.

Warranty Notes

The barrier-free manual prints a 30 year limited warranty against manufacturing defects, with supplied component parts covered for one year, voided if the unit is moved from its first installation or installed contrary to the instructions. The low-threshold gel coat manual prints a three year term for its gel coat units. Confirm the term for your specific unit with the team when you register it, and see warranty coverage for Ella shower bases for the 10-day claim window. Care after installation is in caring for Ella showers.

Common Questions

How much bigger than the shower is the pocket?
On the barrier-free roll-in units, the framing pocket is 1/4 inch larger than the shower to give maneuvering room, and the manual allows framing closer if 1/4 inch is unreasonable. Doubling the front studs adds strength, and the design allows a 1/8 inch gap at the seams. The low-threshold manual's framing page gives its own dimensions for each SH unit, so frame to that page for those models.
How flat does the floor need to be?
A roll-in base needs a floor that is flat and within 1/8 inch of level; anything more out of level will prevent a successful installation. Float the floor with leveling compound and let it cure before you proceed. Because the pan is bedded in adhesive over its entire contact area, any voids or humps left in the floor show up later as drainage problems.
Why are the wedges mandatory?
The provided wood wedges sit under the back edge of a low-threshold base and give it its structural support. The manual requires that they be in place and in proper contact with both the unit and the subfloor. Without that contact the base can flex under load, and a flexing base pulls the caulked seams apart.
How many installers?
Two. The barrier-free manual states that two persons are required, both to carry the unit safely and to set the indexed wall panels on the slot-and-pin system. Gel coat units are easily damaged by impact to the back, so never drag or drop one; carry it with two people or a two-wheel dolly.
When is the leak test?
Check for leaks after the supply and drain lines are connected and strapped and the trim is installed, but before the wallboard goes on and closes off plumbing access. On the roll-in units the valve wall is the last access to the supply connections, so complete and test the valve connections while that wall is still off. Once the wallboard is up, reaching a leak means opening the wall.
In what order do the wall panels go on?
Roll-in units: set the back wall first, then the side walls, indexed by the slot-and-pin system and pushed tight before fastening. Low-threshold three-piece units: the left wall, then the right. Low-threshold four-piece units: the back wall first, then the left and right walls, with the wet wall last so the valve and supply connections stay accessible as long as possible.
Can I set the base in mortar instead of adhesive?
The roll-in manual calls for solid wood flooring adhesive or 100 percent silicone troweled over the entire pan contact area with a 1/2 inch notched trowel, with non-shrink thin-set used only to fill the drain box and never above the floor line. The adhesive has a working life of roughly an hour, so the remaining steps follow straight through. Follow the manual's method rather than substituting mortar, because the warranty is voided if a unit is installed contrary to the instructions.
Where do the grab bars and seat go?
Surface-mount accessories such as grab bars and a seat are added after the seams have cured, so the silicone joints are not disturbed. Involve the person who will use the shower in the placement so the bars land where they are actually needed for support. If you are unsure about placement for your unit, your Ella dealer or the team at (800) 480-6850 can advise.

For anything specific to your unit or configuration, open a ticket at ellasbubbles.com/support or call (800) 480-6850 and the team will walk your installer through it.

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