14/05/2026
A waterbar is important in a foundation because it helps stop water from passing through construction joints, expansion joints, or cracks in concrete. It acts like a waterproof seal inside the concrete.
Why it is important:
Prevents water leakage into basements, underground tanks, lift pits, toilets, retaining walls, and foundations.
Protects steel reinforcement from rust caused by moisture.
Increases durability of the structure by reducing water damage.
Prevents dampness and seepage on walls and floors.
Helps avoid cracking and weakening of concrete over time.
Where it is used:
Usually installed at:
Raft foundations
Retaining walls
Water tanks
Basement joints
Slab-to-wall joints
Expansion/construction joints
Common types:
PVC waterbar
Rubber waterbar
Bentonite waterbar (swells when wet)
Simple example:
When concrete is poured in two stages, a joint forms between old and new concrete. Water can pass through this joint. A waterbar is placed in the middle of the joint to block the water path.
