Sunken Slab Waterproofing
Fix bathroom and kitchen slab leaks without full demolition — our crystalline treatment and lightweight screed system resolves leaks from above, sparing the ceiling of the flat below.
Get Free InspectionUnderstanding the Problem
What is Sunken Slab Waterproofing?
In Indian apartment construction, bathrooms and kitchens are typically built with a sunken slab — the RCC floor is cast 300–450 mm below the finished floor level to accommodate plumbing pipes. The void between the structural slab and the tile finish is filled with broken brick (brick-bat coba) and sand, creating a hidden cavity that is constantly exposed to water from drain pipes and wet surfaces above.
Over time — especially in Kanpur's older apartment buildings in areas like Kidwai Nagar, Arya Nagar, and Govind Nagar — this fill becomes saturated, pipes corrode or crack, and water seeps through the structural slab into the flat below. Traditional repair means breaking the entire floor, which is disruptive and expensive.
Our system uses targeted core drilling to access and remove the old fill, crystalline waterproofing slurry applied to the bare slab surface, and lightweight aggregate refill — all without demolishing the floor or disturbing the neighbour's ceiling below.
Signs Your Sunken Slab is Failing
- ✓Wet or damp patches on the ceiling of the flat directly below your bathroom
- ✓Persistent musty smell in the bathroom even after cleaning
- ✓Bubbling, hollow, or cracked floor tiles in bathroom or kitchen
- ✓Yellow or brown water staining on the ceiling below
- ✓Mould growing in the lower flat's ceiling corner
- ✓Higher-than-expected water bills suggesting hidden pipe leaks
Our Process
Our 5-Step Approach
A precise, minimally invasive process that fixes the problem at source without requiring full demolition.
Core Drilling
Strategic 50 mm core holes drilled through the floor slab to access the sunken fill material and establish leak pathways — without breaking the entire floor or disturbing the ceiling below.
Leak Tracing
Drain pipes and water supply lines inside the sunken void are pressure-tested and visually inspected via bore scope camera. Exact leak sources — pipe joints, cracks, or failed seals — are identified and documented.
Old Fill Removal
Saturated, bacteria-laden old fill material (typically broken brick or sand) is removed through the core holes using suction and hand tools. The void is cleaned, dried, and prepared for the new waterproof system.
Crystalline Slurry Base
Two coats of crystalline cementitious slurry applied to the bare concrete slab surface and around all pipe penetrations. Crystals penetrate the concrete and permanently seal hairline cracks even under hydrostatic pressure.
Lightweight Screed & Tile
Void refilled with lightweight aggregate concrete (600 kg/m³) topped with polymer-modified waterproof screed. Existing tiles re-laid on C2TE flexible adhesive with epoxy grout at all joints.
Specified Materials
Products We Use
EpoxyFill LV
Low-viscosity epoxy injection resin for sealing structural cracks in the RCC slab and filling voids at pipe entry points. Sets rigid under wet conditions — suitable for injection even when the substrate is still damp.
- Compressive strength: 50 MPa
- Viscosity: 200 cPs (low)
- Pot life: 25 min at 30°C
LWA Screed
Lightweight aggregate concrete mix for refilling the sunken void. Significantly lighter than traditional brick-bat coba fill, reducing dead load on the slab while providing a stable, level base for the waterproof screed.
- Dry density: 600 kg/m³
- Compressive strength: 15 MPa
- Thermal insulation: better than brick bat
PolyShield Waterproof Screed
Polymer-modified, fibre-reinforced waterproof screed applied as the final layer over the LWA refill. Provides a fully waterproof, tile-ready surface and can be laid to precise slopes for drainage.
- Application rate: 3 kg/m² at 10 mm
- Water impermeability: 100%
- Minimum tile-laying time: 48 hrs
Why Choose Katiyar Ventures?
10-Yr
Warranty on Materials
500+
Projects Completed
Free
On-Site Inspection
100%
Waterproof Systems
Common Questions
Frequently Asked Questions
Do you have to break all the floor tiles to do this work?+
How long does the complete sunken slab treatment take?+
Can you fix the sunken slab without breaking the ceiling of the flat below?+
Does the waterproofing treatment affect existing water supply or drain pipes?+
Bathroom Leaking Into the Flat Below?
Book a free sunken slab inspection in Kanpur today. We'll trace the leak source with a bore-scope camera and give you a clear, no-obligation repair plan.
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