So I set and level my tub in a morter bed and attached the flange to the studs. At the bottom one third or so of the front flange is not touching but the tub feels solidly in place without noticeable flexing. Its off by about 1/4" at the corner between the tub and subfloor

Should I still shim this gap with composite shims or just caulk(kerdfix) it? I'm worried the shimming could lead to eventual squeeking at the lip edge some have mentioned. Outside of the tub will be getting ditra and tile so I could pack the gap with thinset as well but that may crack over time

1 Answer 1


If its not exposed much for appearance, cheap architectural, sub-floor adhesive prevents squeaks on 2x8 sub-floors and sticks to everything. High VOC types dryfast but are obsolete so the LePages PL * Polyurethane bond in a large tube may take a day get firm and few days to harden like ABS.

  • apply with a caulking gun.
  • extremely durable to everything and consider it permanent unlike Silicone.
  • usually light tan color.
    • this my best adhesive and not brittle like epoxy.
  • Tony are you saying apply subfloor adhesive alone or to glue the shims in with the subfloor adhesive? Is there strength in the adhesive to bridge the gap?
    – redlude97
    Sep 13, 2020 at 20:39
  • Yes plenty of strength, stronger than anything else. Use anywhere. But takes time to harden Sep 13, 2020 at 22:16

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