Aparna Constructions Residential Tower Terrace

Project Overview

Scale: 65,000 sq ft across the podium deck and rooftop terraces of a multi-tower residential development by Aparna Constructions in Hyderabad.

Aparna required a waterproofing contractor who could deliver consistent, inspectable work across a large contiguous substrate with multiple penetrations — plumbing risers, drainage outlets, expansion joints, and utility conduit crossings — while coordinating with civil finishing teams on a live construction timeline.

Victoria Waterproofing was appointed after a site visit and system specification review. Method selected: SBR-modified cementitious membrane. Application sequence: substrate preparation → crack repair and penetration sealing → primer coat → two-coat SBR system → protection screed.

Handover: March 2023. Eighteen months without a single leak complaint as of October 2024.

Substrate Condition at Intake

The podium slab presented the typical challenges of large-scale cast-in-situ concrete: variable surface porosity, multiple construction joints, and 11 plumbing risers requiring individual collar treatment.

Existing surface treatment on the rooftop terrace was a crystalline slurry from the original construction phase — partially delaminated, with active moisture migration visible at two corners and one drainage outlet. This layer was stripped entirely before the new system was applied. Patching over a failing membrane is how most re-waterproofing jobs fail inside three years. We do not do that.

Crack mapping on the podium deck identified 17 hairline cracks. All were treated with cementitious crack filler before primer application. Drainage slopes were surveyed and corrected at three points where standing water had been reported after rain.

Method Selection Rationale

SBR-modified cementitious was selected over torch-on bituminous membrane and polyurethane coating for three reasons specific to this project.

First, the tile overlay. The developer's finish specification called for full-bed tile over the podium deck. Torch-on membrane systems are not ideal as a tile bedding substrate — the surface remains hydrophobic, reducing tile adhesion. Cementitious systems accept tile bed mortar directly without a screed intermediate layer.

Second, application speed at this scale. A 28-member crew can apply cementitious system across large open areas with consistent wet film thickness and without the fire-safety protocols that torch-on requires on an occupied construction site. The phased zone approach — three zones, with civil finishing teams continuing work in completed zones while waterproofing was still in progress elsewhere — kept the overall project timeline on schedule.

Third, substrate compatibility. The podium slab had minor active seepage at one expansion joint during application. Cementitious systems can be applied to damp substrates. Polyurethane requires a fully dry substrate — a condition difficult to guarantee on a large podium with active water in the ground beam system.

Execution Highlights

The expansion joint treatment was the most technically demanding aspect of the project. Fourteen expansion joints crossed the podium deck at irregular intervals, each requiring a flexible sealant backing rod, polyurethane sealant infill, and a bond-breaker membrane bridge detail before the main waterproofing coats were applied. This is the detail that most contractors skip, treat with filler, or price out of scope. These joints are where the building moves. Any waterproofing system that bonds rigidly across a movement joint will crack at the joint and fail. Every joint on this project received the full flexible detail.

Penetration sealing at 11 plumbing risers was done with pre-formed flashing collars, set in SBR slurry and integrated into the main membrane. Each collar was tested with standing water for 24 hours before the protection screed was poured.

Drainage outlet sumps were deepened and re-formed at four locations where the original outlet geometry had created standing water pockets.

Post-Handover

The 5-year written warranty was issued on company letterhead, project-specific, covering the full 65,000 sq ft system. Warranty terms: repair or re-application at no charge for any leak attributable to system failure within the warranty period.

Post-monsoon site visits were completed in September 2023 and October 2024. Zero leak complaints. No warranty claims. The system is performing as specified.

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Site inspection and technical specification by Subhash Chander, Victoria Waterproofing.