I have a house in the City of St. Louis, and I'm installing a "Family Room" in the basement. The house is a 1929 brick bungalow and the foundation is a stone on the inside, 3-hole brick, and stone on the outside. The basement is dry, but on a very heavy or steady all-day rain we will get a little water in the basement. We also have areas where we see mold on the stone, but since installing a de-humidifier, that is pretty much under control.

With all that said, I'm wondering if it would be wise to install a sump pump. We will be painting the inside stone walls with a masonary sealing paint from Behr and I'll use a water seal on the outside. I do plan on installing drywall in front of the stone wall with a vapor barrier and insulation, but I will also install vent slots to allow the air to move. (Still leaving the de-humidifier in the basement.) If it matters, I'll be installing a wet bar and a shower as well. (There is a 1/2 bath in the basement already.)

So... Is a Sump Pump a good idea, or belt & suspenders approach? (I'll be checking with the building code here as well.)

Thank you for your time.