I noticed about 5 or 6 hard bumps/lumps in the shower floor today while cleaning. The last time I got down on the floor and deep cleaned was about 3 months ago and did not notice them at the time. We use a bath mat that covers the area.

They are hard to the touch. I think our shower is acrylic material. House was bought new build about a year and 5 months ago. Warranty only covers the first year.

Does anyone know what these are and possible fixes?

The shower is one big piece. Only thing out of the ordinary I can think of is that the shower floor started creaking about a year after we moved in. No signs of leaks around the shower or adjacent rooms.

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1 Answer 1


There are really only two things it can be--delamination of the surface layer or bulges from pressure on the underside.

Press on them to see if they flex like bubbles. If so, that would indicate a failure of the unit's structure.

Otherwise, maybe an inappropriately rough substrate was used under the pan, such as aggregate concrete, and the stones are pressing sharply against the pan under weight.

In either case, replacement is probably the only long-term solution, though that's not necessarily warranted until leaks develop due to full depth cracks.

  • Maybe the installer used a mortar bed that had "chunks" in it, and the shower base has flexed off the bed, and some of the chunks are loose and got between the bed and base?
    – Huesmann
    Commented Feb 19 at 15:27

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