Signs & Causes of Basement Water Intrusion

How Can I Tell If My Basement Has Water Seepage?

With obvious signs like standing puddles of water or flooding during heavy rains, it can sometimes be easy to tell when your basement needs water direction installations.

Six Common Places Water Can Enter A Basement:


  1. Floor wall joints
  2. Floor cracks
  3. Wall cracks
  4. Basement window
  5. Bulkhead door
  6. Sill plate

6 areas where water can enter your home.Here are some less noticeable symptoms that basement water seepage is occurring:

  • Leaky cracks in walls or floors
  • Sagging insulation
  • Structural damage, sagging floor joists
  • Efflorescence / Powdery substance on wood beams
  • Damp, musty odors
  • Increased allergies

What Causes Basement and Foundation Leaks?

A flooded basement.

Did You Know?

Experts agree that the most common water entry points are joints where the basement floor and wall meet.

Expanding soils around your basement floor joints (footer) twist and separate the concrete joints, allowing water to pass through.

St. Louis Clay Soil Expansion

Cracked and leaking basement walls are extremely common in St. Louis County and the surrounding areas, due to our predominantly clay soil.

Clay is an unforgiving soil type. When the soils surrounding your basement walls expand, they apply lateral pressure on the wall.

Soils with excess moisture expand and exert horizontal pressure on foundation walls, while drought causes contraction that relieves the pressure. The on-going cycle of expansion and contraction causes cracking, bowing and buckling of basement walls and floors. Cracked and damaged walls and floors allow water to seep into the interiror of your home.

Your wall is primarily designed for vertical support. Hydraulic lateral pressure is strong enough to push the basement wall materials inward toward the center of your home.

Usually cracks are most noticeable in the weakest part of your wall: the middle section of the foundation wall, furthest from the edges.

Your wall is strong, and built to withstand incredible forces. But the force of water can’t be matched.

Improper Drainage Around Your House

Water pressure on the outside wall of your foundation can build up due to poor drainage. This incredible hydraulic force pushes up against the side of your basement walls creating cracks and inward bowing in your basement walls.

Plumbing leaks, heavy rains, floods or drainage from gutter downspouts cause excessive water to surround your home.

Poorly designed slopes in your landscaping may channel water towards your home’s foundation.

Structure Settlement

Every home shifts and settles into its supporting soil over time. This happens weight of the house combines with variations in soil compaction, permeability, swelling, and viscosity. Every foundation settles differently — many times unevenly. Uneven settling usually causes leaky cracks in your foundation and basement.

In most St. Louis homes, the basement walls and floor are constructed separately. Because they’re poured as separate pieces, there is an entry point for water and moisture where the basement walls meet the basement floor or slab.

Other Causes

  • Poorly Sealed Basement Windows & Pipes
  • Tree root damage to foundation wall
  • Un-dealt with pests