What Is a Bathtub Flange and What Does It Do?

A bathtub flange is the lip or strip along the edge of a tub where it meets the wall. The tile or wall panel overlaps it, so water running down the wall is carried back into the tub instead of behind it. On a conventional bathtub that lip is molded into the rim. Ella walk-in tubs have a flat deck edge with no built-in lip, so the flange is a thin waterproof strip that your installer bonds to the tub edge with silicone during installation, as described in What Is a Tile Flange on a Walk-In Tub?.

Three Parts of a Walk-In Tub That Get Called a Flange

The word comes up in three different places on an Ella tub, and only the first is what people mean by a bathtub flange.

• The tile flange at the wall. Also called a tiling flange, a glue-up flange or a flange band. This is the water barrier between the tub edge and the wall finish, and the rest of this page is about it.
• The flange of a deck-mounted fitting. A push control, switch or aromatherapy canister has a rim that sits over the edge of the hole cut for it. That rim hides the fine surface lines that can appear around a freshly cut hole, which Hairline Lines Around a Hole Cut in the Tub Deck explains are a surface effect of the cut that Ella's technical support has never seen extend.
• The swivel tray's mounting flange. The plastic fitting near the door that the tray's 2 inch pin slides into. It is a replaceable accessory part, covered in What Are My Options If My Swivel Tray Broke or Does Not Fit?.

Why an Ella Tub Has No Molded Lip

Installers who have set conventional bathtubs sometimes look for the molded flange on an Ella tub and worry when they cannot find one. The flat deck is by design, and no Ella walk-in tub ships with a tile flange in the crate. Instead, the installation manual calls for a rustproof, waterproof strip about 5 inches tall, glued to the tub edge with 100 percent silicone so it overlaps the edge by about 2 inches. Any 1/8 inch or 3/16 inch rust-proof, waterproof material will do the job, whether acrylic, thin stainless steel or fiberglass, and the tile or wall panels then overlap the flange and the deck with every joint siliconed.

The current Ella part for this role is the flexible glue-up tile flange kit, listed as FlangeBand and recorded by support under the part code EB-FLANGE. The reason a flexible strip is used instead of a rigid plastic lip is movement. The membrane bonds with the silicone to form a solid water barrier that stays flexible through floor contraction, expansion and joint movement, which a rigid flange cannot follow. My Tub Has No Tile Lip. Which Flange Do I Use? covers what to do when the walls were planned around a molded lip that is not there.

What Is in the Kit and Which Length You Need

The standard kit contains one roll of flexible 4 inch wide waterproof membrane with an integrated 1 1/4 inch siliconized adhesive strip, a spreading spatula, a cardboard alignment guide and two alcohol surface-cleaning tissues. The pink portion is the membrane; the rest of the strip is a cloth-like material that gets tiled over. The strip is reversible, with a pink side and a red side, and which side faces out depends on whether the fixture already has an integral flange. The installation video on this page shows the kit contents and how the alignment card is used to mark the strip position on the walls before the tub goes in.

The strip runs along every side of the tub that meets a wall, so the length depends on your alcove:

• 124 inch kit: most Ella walk-in tubs in a standard 60 inch three-wall alcove
• 132 inch: Big4One or TransferXXL, and the right pick for a 60 by 36 shower base
• 136 inch: LayDown72
• 144 inch: Escape or ShaK
• 152 inch: Big4Two
• Bulk box: a single 164 foot roll for contractors, enough for sixteen projects at 124 inches each, without the spatula, guide or tissues

If you are between sizes, the bigger strip is fine when you want extra material for corners. Measure the wall perimeter at deck height and ask your Ella dealer or the team at (800) 480-6850 if you are unsure. The Glue-Up Tile Flange Kit goes through the box, the lengths and the orientation in full.

How the Flange Goes on, and When

1. Level the tub with every leg bearing on the floor and complete the pre-installation water test before any wall is finished. Fixing a leak behind finished tile is far more disruptive than fixing it now.
2. Measure the total run of tub edge that meets a wall, back plus each end, at deck height, and match it to a kit length.
3. Clean the tub edge with the alcohol tissues in the kit.
4. Bond the flange with 100 percent silicone so it overlaps the tub edge, with the correct colored side facing out.
5. Run the tile or wall panel down over the flange and onto the deck.
6. Silicone every joint, including where an extension panel meets the tub and where an end panel meets the wall.

Because the strip is flexible, it can go on during or after the tub is installed, and the same approach applies to a shower base, where the strip can be added after the base is set. Existing wall tile that is sound and properly sealed can stay, with your installer confirming its condition. Two things to know before delivery day: the flange ships separately by parcel carrier rather than in the crate with the tub, so do not report it missing when the tub arrives, and the ShaK is not designed to be tiled in directly, so talk with technical support before planning tile around one. When you request a flange through where you purchased the tub or the team at (800) 480-6850, include your tub model so the right length ships. Once the walls are finished, keep the caulk line between the tub and the wall in good condition and re-caulk if it cracks or pulls away.

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

Related Guides

• How Do You Install a Tile Flange on a Tub or Shower Base?
• Tile Flange, Caulking, and Finishing the Walls Around Your Walk-In Tub
• What Is a Shower Flange and What Does It Do?

Common Questions