Is there any reason to NOT use these in a bathroom or kitchen?

You can use our 8mm Strong Rubber Tiles in a bathroom or kitchen. In bathrooms, you will want to seal the edges like you would a vinyl floor to create a water-tight floor that won't allow water to flow to the subfloor. In a kitchen, the only thing you will need to worry about will be oils. Oils over time can break down the binder in our rubber flooring, so it is imperative that you clean up any spilled oils as quickly as possible. Other than that, these rubber tiles are very slip-resistant and more so when wet and are very easy to clean and maintain. Since these tiles are semi-porous, we would recommend that you seal the floor with our Rubber Floor Finish and Sealer in both installations.