How to waterproof your basement?


 

Leakage in basement is common and it is important to understand causes & appropriate measures to be taken for prevention. Lots of basements are not even being used due to dampness. Damp basement is not only uncomfortable to use but can lead to hazardous health problems. Basement waterproofing is very crucial due to all these factors.

Understanding the source:

To provide a perfect waterproof solution in your basement, identifying and understanding of problem and water source are very necessary. There are lots of possible reasons for water leakages and there are waterproofing solutions accordingly.

Sources of dampness and water:

  • Rain and ground water through retaining walls or slab
  • Leakage through underground public drain system
  • Leakage through drainage
  • Construction joints in retaining walls or structural cracks
  • Humid air that comes in basement and condenses on cooler surfaces
  • Interior moisture such as bathroom, kitchen etc

Basement waterproofing solutions:

Building materials like concrete, mortar, bricks etc. have pores which absorb water from surrounding soil or from any leak drainage point. Capillaries and hydrostatic pressure create dampness and water leakage in basement. We discussed in our previous post how these capillaries are formed in structures.

How to waterproof your basement:

Waterproofing treatments and measures taken in basement should be opted according to problem or level of hydrostatic pressure. As mentioned above there are various sources of water and dampness in basement. There are different levels of hydrostatic pressure in different basement sites. For damp surfaces in basement, any cementitous coating with high tensile strength and flexibility can work well.

However, if there is higher water pressure or water is leaking in basement, a normal coating with protective plaster on it will not work. Since water pressure is high, coating will be cracked and damaged with plaster. In such cases, stones or marbles with high comprehensive strength and adhesive mortar are recommended to protect coatings.

Basement waterproofing Methods:

Method-1: Basement Waterproofing treatment for damp basement (If there is not water leakage)

Causes: Rain or Ground water, leakage through drainage etc.

Step-1: Surface preparation:

First, we should remove plaster from damp areas and clean the brick or RCC surface with brooms, brushes and detergents etc. to remove all dirt, dust. No waterproof coating should be applied on damaged plaster since coatings would be cracked and damaged with plaster.

Step-2

After removing plaster and cleaning the surface, all joints, cracks should be filled with polymer formulated system. Repairing and grouting should also be done if required. Gola should be formed at the joints of retaining walls and slab.

Surface preparation-1

Removing Plaster

Surface preparation-2

Cleaning the surface with wire brush

 

 

 

 

 

 

Step-3

Applying two coats of cementitious coating with proper formulation as recommended by chemical manufactures. Chemical should have quality to make cementitious coating flexible enough to bear contraction & expansion movements, earthquakes etc. If coating does not have high tensile strength and flexibility any movement can develop cracks in it which provide water way to make your basement damp again.

Step-4

Provide protective plaster to coatings. Protective plaster is required to provide comprehensive strength to coating so that coating can bear negative water pressure without being damaged.

Seal all holes, brick’s joints & all gaps

Seal all holes, brick’s joints & all gaps

Applying Cementitious Coating

 

 

 

 

 

 

 

Method-2: Basement Waterproofing treatment for damp basement (If there is not water leakage)

Causes:

  • Humid air that comes in basement and condenses on cooler surfaces
  • Interior moisture such as bathroom, kitchen etc

If basement is damp due to above mentioned causes, plaster (in step-4) should have silicone based chemical that can protect plaster from water presented in humid or environment.

Method-3: Basement Waterproofing treatment for water leaking basement

Basement waterproofing

Causes:

  • high water pressure due to Rain or Ground water, excessive leakage through drainage etc.
  • Construction joints in retaining walls or slab

Lots of basements get water flooded during rainy seasons due to water leakage though walls or slab. Construction joints are main reasons for such cases. More often, due to inadequate drain systems, rain water creates water logging in public drainage which sometime backfill building’s drainage and thus stored water seeps through weaker area of building. In such cases, concrete also get damaged and become more porous.

Though, it would always be better if we can get the source repaired but in most of the cases, it is very difficult to get outer surface of retaining walls. In such cases we should use Injection grouting systems for basement waterproofing

Step-1 Injection Grouting

Injection grouting with cement slurries of different viscosities & expansive plasticizing agent. So that concrete can be repaired and can get required strength.

Step-2

After injection grouting surface preparation, joint filling and cementitious coating should be applied (discussed above)

Step-3

In such cases protective layer needs additional comprehensive strength that a normal plaster can not provide. Hence, stones or marble should be fixed over the coatings with slurry (cement+chemical) with greater adhesive strength.

Injection Grouting

Fixing and sealing the Nozzles

Injection Grouting2

Injection Grouting