Waterproofing Guide: Terrace, Bathroom and Basement

Waterproofing is cheap to do correctly and brutally expensive to fix later. In Nagpur, the monsoon exposes every shortcut taken during construction.

Terrace waterproofing

The correct sequence is surface preparation, crack filling, a cementitious or polyurethane membrane, protective screed with proper slope, and finally the tile or China mosaic finish. Slope must be at least 1 in 100 towards the outlet.

Where terraces fail

• No coving at the wall junction — water finds the 90-degree corner
• Membrane not carried 300mm up the parapet
• Rainwater outlet not recessed and sealed with a puddle flange

Bathroom and sunken slab

Sunken portions should be tested by ponding for 48 hours before filling. Use lightweight filling, not construction debris, and apply a second membrane coat over the filled level.

Basement and retaining walls

Where the water table is high, external tanking plus a drainage layer is essential. Internal negative-side treatment alone is a temporary measure.

Warranty expectations

A serious contractor gives a written waterproofing warranty with a defined duration and a named system. Ask which product, which coats, and what DFT.

Simple checks you can run

• Ponding test on every terrace and bathroom before flooring
• Photograph coving and membrane upturns before the screed is laid
• Verify outlet levels are the lowest point on the slab