damp basement will also increase your heating and air-conditioning bills, Damp Proofing or Waterproofing Foundation Walls, In the summer, the humidity in the air condenses on the basement walls, Pressure in the soil forces it through the foundation walls into the basement. If a cellar floor got wet during the spring thaw, Wide roof overhangs to keep rain away from the foundation, Gutters at the roof eaves these gutters should, The humidity in your basement may be coming from the soil water can leak through.