Questions & Answers

Just joined so not sure what all the etiquette rules are, so apologizing upfront if do something wrong... This is long so appreciate reading through all of it. Thanks!

I am an experienced DIYer whose projects are usually permitted and have the following questions regarding my planned 2nd-floor shower-to-tub conversion. Refer to the visual below for the details and scope of work. Note that I have already checked for proper joist support with a live and dead load calculation. Plan to use a freestanding tub if cannot find an alcove tub due to the sizing.

1) Is there any requirement in the California Residential or Plumbing Code which requires an alcove bathtub to have a vertical lip along the upper edge (which ends up behind wall tiling to prevent leakage at the tile-to-tub gap)?

If so, which section(s)?

Why: I plan to pull permits, and freestanding bathtubs don't have the edge lips/flanges...

Note that I can mechanically secure all three hidden sides of the tub outer skins to the wall framing since have access from the other framing side (using blind & reinforced fasteners using holes through the outer tub skin).

2) If no code requirement, then want advice for sealing the vertical gap between the tub backerboard plus tile: use a 100% silicone or a grout/silicone hybrid to fill the gap during installation?

Or use both: backerboard-to-tub gets the hybrid for backup protection and tile-to-tub gets the silicone?

3) Or is it best to bond a strip of acrylic to the three tub upper/alcove edges to form a 0.5"-tall lip along the top of the tub so have another layer of protection to prevent leakage to the floor behind the caulking?

For example, using strips cut from this: Clear Scratch- and UV-Resistant Cast Acrylic Sheet, 24" x 48" x 1/16" | McMaster-Carr which are bonded to the outer upper edge of the tub...

I would float this new lip behind the tiling so not mechanically attached to the framing (would use only one silicone caulk seal then)...

Has anyone ever added a lip or flange to a freestanding tube before?

Worth it or just rely on double caulk seals?

4) Anyone have experience using a freestanding bathtub in an alcove installation?

Tips?

5) Looking for a manufacturer of an acrylic tub with my required dimensions AND a center drain so can you pass along suggestions for a <=50" length, <=36" wide white tub?

Also, can be a drop-in tub if I can also seal the vertical gap between the tile and tub flange.

Right now, only supplier might be PENGHANG WORLDWIDE, but not sure if they sell one unit only. Anyone know?

If I remodel a little more, then I can fit a 51" like these which seem to be all the same OEM part:

HHK HOME 51'' x 0'' Freestanding Soaking Acrylic Bathtub | Wayfair

VR SUPPLIERS 51.18'' x Freestanding Soaking Acrylic Bathtub | Wayfair

Topcraft 51" L X 28" W Freestanding Soaking Acrylic Bathtub | Wayfair

PENGFANG WORLDWIDE LLC 51.25'' x 27.5'' Freestanding Soaking Acrylic Bathtub | Wayfair

Thank you in advance!