Waterproofing refers to the process of making a structure water-resistant so that it remains relatively unaffected by water or resists the ingress of water under specific conditions. In building construction, waterproofing is a critical element to prevent water from penetrating through walls, roofs, basements, and other structural elements. It ensures the durability and longevity of the structure by preventing water-related damage such as dampness, corrosion, mold formation, and structural weakening.

Basements are particularly prone to water seepage due to their location below ground level. Groundwater, rainwater, and capillary action from the soil can lead to water entering the basement through walls, floor slabs, and joints. Therefore, waterproofing of basements is a vital step during building construction to protect interior spaces from water damage.

### Importance of Basement Waterproofing

1. Prevents Water Seepage: Protects the basement from rainwater, groundwater, or plumbing leaks.
2. Improves Structural Integrity: Reduces the risk of corrosion of reinforcement bars and other structural elements.
3. Enhances Indoor Air Quality: Prevents mold and mildew formation due to dampness.
4. Increases Property Value: A dry and well-maintained basement adds to the value of the building.
5. Prevents Electrical Hazards: Water intrusion in basements with electrical installations can be dangerous.

### Sources of Basement Water Seepage

* Hydrostatic pressure from underground water table
* Capillary action of water through soil and concrete
* Rainwater accumulation around foundation
* Plumbing leaks and poor drainage
* Cracks in basement walls or floor slab

### Procedure of Waterproofing of Basement

Waterproofing of basements can be broadly categorized into pre-construction and post-construction methods. The procedure involves multiple steps including surface preparation, crack treatment, selection of materials, application techniques, and final protection layers. Waterproofing can be done using various systems such as membrane waterproofing, crystalline waterproofing, chemical coatings, cementitious systems, etc.

#### 1. Site Preparation and Surface Cleaning

Before starting the waterproofing procedure, it is essential to prepare the surface:

* Remove all dirt, debris, oil, grease, and loose particles from the surface.
* Ensure that the surface is structurally sound and free from laitance.
* If waterproofing is being done post-construction, identify and mark all existing cracks and leakage points.
* Remove honeycombs, and fill voids or gaps with appropriate repair mortar.

#### 2. Repair of Cracks and Joints

* Cracks in concrete should be opened into a ‘V’ shape and cleaned.
* Inject non-shrink epoxy grout or polyurethane-based injection grout into deep cracks.
* Surface cracks are treated using cement-based polymer-modified repair mortar.
* Cold joints between wall and floor slab are treated with hydrophilic PVC water stops or swelling water bars.

#### 3. Application of Primer or Slurry Coat

* A primer is applied on the clean and repaired surface to improve the bonding of waterproofing membranes.
* In the case of cementitious coatings, a slurry coat may be applied to provide an even surface and initial protection.

#### 4. Waterproofing of Raft/Foundation Slab

a) Membrane Waterproofing (Torch-on or