Terrace waterproofing at an apartment building in Panjim, Goa
A residential apartment building in Altinho, Panjim developed active terrace leakage through the ceilings of its top-floor apartment during the 2024 monsoon.
The exposed terrace had a movement-related crack, a blocked rainwater outlet and failed parapet details. These defects allowed standing rainwater to enter the terrace construction and spread into the drawing room and adjoining bedroom below.
The terrace was repaired and waterproofed using an APP-modified bituminous membrane system, with accompanying drainage, screed, crack, parapet and coping repairs.
Project overview
Location: Altinho, Panjim, North Goa
Property: Mid-rise residential apartment building
Building configuration: Ground floor plus three upper floors; six apartments
Property age: Approximately 14 years
Project completed: August 2024
Terrace area: Approximately 1,400 sq. ft.
Affected ceiling area: Approximately 280 sq. ft. across two rooms
Project duration: Nine working days
Treatment: Drainage correction, crack and screed repair, APP membrane waterproofing and parapet repairs
Testing: 48-hour ponding test
Warranty: Five-year workmanship warranty on the specified membrane and junction repairs
The problem
The owners of the top-floor apartment first noticed expanding dark stains on their drawing-room ceiling during the early weeks of the 2024 monsoon.
Within approximately ten days, the staining spread to an adjoining bedroom. Following a period of heavy overnight rain, water began dripping from a ceiling light fitting.
The apartment had experienced intermittent ceiling dampness during the previous two monsoons, but the marks had been attributed to condensation.
The incident near the electrical fitting led the building’s housing society to arrange a complete terrace inspection.
What the terrace inspection found
The inspection covered the full terrace surface, parapet junctions, coping, drainage outlets and service penetrations.
Three principal failure zones were identified.
A movement-related terrace crack
A hairline crack approximately 12 metres long extended across the terrace. It had passed through the existing waterproof coating and into the screed below.
The original coating had become brittle after years of exposure to sunlight, heat and seasonal movement. A previous local repair had involved applying another coating over the visible crack without opening, filling or reinforcing it.
Movement subsequently reopened the crack beneath the repair.
A blocked rainwater outlet
A rainwater outlet at the southern end of the terrace was completely blocked by accumulated debris.
Water collected around this low-lying area after heavy rain instead of draining from the terrace. Prolonged standing water increased the amount of moisture entering through the crack and adjacent junctions.
Failed parapet coping and junctions
Several joints in the parapet coping had cracked. Rainwater was entering through the top of the parapet and tracking down towards the terrace-wall junction.
The perimeter detail was therefore contributing to leakage independently of the main terrace crack.
Confirming the entry points
A controlled water test was conducted during the diagnosis.
Water penetration corresponded with the damp areas visible on the ceilings below, confirming that the terrace crack, standing-water zone and parapet junctions were contributing to the leakage.
This allowed the repair to address the complete terrace system rather than treating only the most visible crack.
Why the earlier repair failed
A previous contractor had applied a waterproof coating over the visible terrace crack approximately two years earlier.
The treatment provided partial relief during its first monsoon but failed again because:
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The crack had not been opened and prepared.
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No flexible crack treatment or reinforcement was installed.
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The drainage blockage remained unresolved.
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The parapet coping and perimeter junctions were not repaired.
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Movement continued beneath the new surface coating.
The project therefore required drainage and civil repairs in addition to a new waterproofing layer.
Terrace repair and waterproofing
Restoring the drainage
The blocked rainwater outlet was cleared and rodded. Silt, moss and organic debris were removed from the terrace.
A larger outlet collar was installed to improve drainage and reduce the likelihood of future obstruction by leaves and monsoon debris.
Removing failed material
The deteriorated waterproof coating was removed around the principal failure zones to expose a sound substrate.
Hollow and delaminated screed sections were identified and broken out. Areas damaged by standing water were allowed to dry before being rebuilt.
Repairing the crack and screed
The long terrace crack was opened, cleaned and filled with a compatible repair material.
Damaged screed was replaced, and falls were corrected around the low-lying area so that water would move towards the drainage outlet.
Installing the waterproofing membrane
Following surface preparation and priming, an APP-modified bituminous membrane system was installed across the terrace.
The installation included detailing at:
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Sheet overlaps.
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Corners.
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Rainwater outlets.
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Parapet junctions.
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Service penetrations.
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Changes in level.
Repairing the parapet
Failed coping sections were removed and reinstated where required.
Coping joints and the parapet-to-terrace junction were resealed with a flexible weather-resistant sealant to prevent water entering from the perimeter.
Working during the Goa monsoon
The building remained occupied throughout the nine-day project.
Because the work took place during the monsoon, each stage was planned around available dry-weather windows. Surface moisture was checked before primer and membrane application.
Residents of the top-floor apartment temporarily vacated during the heat-applied membrane work as a precaution against fumes entering the apartment.
Access to the terrace was through the building’s internal staircase and a restricted roof hatch, requiring materials and equipment to be transported in smaller sections.
Testing and result
A 48-hour ponding test was completed after installation.
The terrace was held under controlled water exposure while the ceilings of the apartment below were monitored. No seepage was observed during the test.
A further inspection was carried out following the first significant rainfall after completion. No fresh stains, dripping or dampness appeared in either of the previously affected rooms.
The ceiling leakage did not return during the remainder of the 2024 monsoon.
A five-year workmanship warranty was provided for the terrace membrane installation, parapet-junction sealing and coping repairs. The warranty requires the rainwater outlet to be cleared before each monsoon and excludes damage caused by later structural alterations or unapproved construction over the treated surface.
What this project demonstrates
Terrace waterproofing cannot be separated from drainage and perimeter detailing.
In this project:
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The surface crack was only one entry point.
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A blocked outlet kept water standing over the damaged area.
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Failed parapet coping introduced water from the terrace perimeter.
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The earlier coating failed because the underlying crack and drainage problems remained untreated.
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The complete repair required crack treatment, screed correction, drainage restoration, membrane installation and parapet repairs.
Project documentation
Terrace inspection: Crack, parapet and drainage defects documented before work began.
Surface preparation: Failed coating and damaged screed removed before waterproofing.
Membrane installation: APP-modified bituminous membrane installed across the prepared terrace.
Need terrace waterproofing in Panjim?
If your terrace has standing water, recurring cracks or leakage into the rooms below, the drainage outlets, parapets and complete roof surface should be inspected before another coating is applied.
Goa Waterproofing Service provides terrace waterproofing for homes, apartment buildings and commercial properties in Panjim and across North Goa.