Basement Waterproofing

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Basement Waterproofing

Basement waterproofing involves techniques and materials used to prevent water from penetrating the basement of a house or a building. Waterproofing a basement that is below ground level can require the application of sealant materials, the installation of drains and sump pumps, and more. 

Waterproofing is usually required by building codes for structures that are built at or below ground level. Waterproofing and drainage considerations are especially important in cases where ground water is likely to build up in the soil or where there is a high water table. 

Water in the soil causes hydrostatic pressure to be exerted underneath basement floors and walls. This hydrostatic pressure can force water in through cracks, which can cause major structural damage as well as mold, decay, and other moisture-related problems.

Causes of water seepage and leaks

Water seepage in basement and crawl spaces usually occurs over long periods of time and can be caused by numerous factors. 

  • Concrete is one of the most commonly used materials in home construction. When pockets of air are not removed, or the mixture is not allowed to cure properly, the concrete can crack, which allows water to force its way through the wall.
  • Foundations (footings) are horizontal pads that define the perimeter of foundation walls. When footings are too narrow or are not laid deep enough, they are susceptible to movement caused by soil erosion.
  • Gutters and downspouts are used to catch rain water as it falls and to discharge it away from houses and buildings. When gutters are clogged or downspouts are broken, rainwater is absorbed by the soil near the foundation, increasing hydrostatic pressure.
  • Weeping tile is a porous plastic drain pipe installed around the perimeter of the house. The main purpose of external weeping tile is preventing water from getting into a basement. However, these pipes can become clogged or damaged, which causes excess water to put pressure on internal walls and basement floors.
  • Water build up inside window wells, after heavy rain or snow, can lead to leaks through basement window seams. Window well covers can be used to prevent water from accumulating in the window well.
  • Ground saturation is another common form of basement leaks. When the footing drain fails the ground around the basement can contain too much water and when the saturation point is met flooding can occur

Warning signs of water damage

Signs that water is seeping into a basement or crawlspace often take years to develop and may not be easily visible. Over time, multiple signs of damage may become evident and could lead to structural failure. 

  • Cracked walls: Cracks may be horizontal, vertical, diagonal or stair-stepped. Severe pressure or structural damage is evident by widening cracks.
  • Buckling walls: Usually caused by hydrostatic pressure. Walls appear to be bowed inward.
  • Peeling paint: Water seeping through walls may lead to bubbling or peeling paint along basement walls.
  • Efflorescence: White, powdery residue found on basement walls near the floor.
  • Mold: Fungi that usually grow in damp, dark areas and can cause respiratory problems after prolonged exposure

Waterproofing methods

Basement can be waterproofed by following methods:

1.Dense monolithic concrete


The main objective is to form a watertight basement using dense high quality reinforced or prestressed concrete by a combination of good material, good workmanship attention to design detail and on site construction method. 
Otherwise, it is called Integral system - It provides protection against water penetration based on the use of admixtures with waterproofing properties in the concrete mix to form concrete with surfaces that are repellent to water, and/or to fill the capillary pores hence reduces the permeability of the concrete.

2.Mastic Asphalt Tanking

The objective of tanking is to provide a continuous waterproof membrane which is applied to the base slab and walls with complete continuity between the two applicat ions. The tanking can be applied externally or internally according to the circumstances prevailing on site. 


3.Cavity / drainage system

A cavity system allows water to enter the structure, contain and direct it to sumps from where it is removed by drainage or pumping. Cavity system is suitable for cases where the use of tanking system (i.e. physically stopping the water), could result in higher water table and/or unacceptable.



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