The most coveted space in any building — until rain arrives and filtration appears in the apartment below. Specialized waterproofing for accessible terraces and walkable rooftops in high-rise buildings.
Accessible terraces and walkable rooftops in high-rise buildings are exposed to weather, foot traffic, and thermal expansion cycles that gradually degrade any waterproofing system. When the membrane fails, water finds its way into the building structure — often appearing as stains, humidity, or visible leaks in the apartment directly below.
Identifying the exact source of infiltration requires more than a visual inspection. A failed membrane may be intact in appearance while water travels horizontally through the slab before emerging elsewhere. This is why a controlled flood test is the starting point of any reliable diagnosis.
Controlled flood test to precisely locate infiltration paths
Complete removal of the failed waterproofing system
New membrane applied with corrected drainage slopes
Final filmed test as documentary proof for the building consortium
Each intervention follows a defined sequence. Understanding each stage helps building administrators and consortiums make informed decisions about the scope and timeline of the work.
The diagnostic phase begins with a site visit to assess the overall condition of the terrace surface, drainage points, and existing membrane. A controlled flood test is then performed — water is retained on the surface for a defined period while the ceiling of the apartment below is monitored for signs of infiltration. This process maps the exact path water follows through the slab and identifies all failure points before any work begins.
Partial repairs applied over a degraded membrane rarely resolve the underlying problem. The standard approach involves complete removal of the existing waterproofing layer — including any protective screed, tiles, or pavers sitting above it — down to the structural slab. This allows a proper inspection of the substrate and ensures the new system bonds correctly to a sound surface.
One of the most common causes of premature membrane failure is inadequate drainage slope. Water that pools on a flat or incorrectly graded surface exerts continuous hydrostatic pressure on the membrane, accelerating deterioration. Before the new membrane is applied, mortar is used to establish proper drainage gradients directing water toward the designated drainage points. This step is essential for the long-term performance of any waterproofing system.
The new waterproofing membrane is applied over the prepared substrate following the manufacturer's specifications and applicable technical standards. Coverage extends to all perimeter edges, drainage collars, pipe penetrations, and any structural joints — the areas where failures most commonly originate. The type of membrane selected depends on the specific conditions of the terrace: traffic load, sun exposure, thermal range, and compatibility with the existing structure.
Once the membrane has cured, a final controlled flood test is conducted under the same conditions as the initial diagnostic. The test and its results are recorded on video, providing the building consortium with documentary evidence that the work was completed correctly and that the terrace is watertight. This filmed record serves as a reference document for future maintenance planning and for any administrative proceedings within the consortium.
Following completion of the work, a written technical report is prepared documenting the initial condition found, the interventions carried out, the materials used, and the results of the final test. This document is intended for the building's administrative records and can be referenced in future maintenance decisions or in the event of any disputes between consortium members regarding the condition of the terrace.
Each phase of the intervention builds on the previous one. Skipping or shortcutting any step compromises the integrity of the final result.
Water is retained on the terrace surface for a measured period. The ceiling below is monitored in real time. This reveals not just where the membrane has failed, but how water travels through the slab structure before it becomes visible as a leak.
The existing membrane, protective layers, and any failed screed are removed entirely. The bare slab is inspected for structural damage, cracks, or deteriorated concrete that must be addressed before waterproofing can begin.
Drainage gradients are established with precision mortar work. The new membrane is then applied in full, covering all edges, penetrations, and joints. The system is designed to direct water away from the slab rather than allowing it to pool.
A second flood test confirms the effectiveness of the new system. The entire test is recorded on video. The building consortium receives this footage as part of the technical documentation package — a permanent record of the completed work.
Different terrace conditions call for different waterproofing approaches. Here is an overview of the main methods used in accessible terrace and walkable rooftop applications.
Modified bitumen membranes applied with a torch are among the most widely used systems for accessible terraces in Argentina. The heat-bonding process creates a continuous, seamless layer that adheres directly to the substrate. This approach requires experienced application to ensure consistent coverage at all overlaps, edges, and penetrations.
Torch-applied membranes are available in different thicknesses and with various surface finishes — including mineral granule or aluminum foil — that provide additional UV protection. They perform well under foot traffic when a protective layer is installed above them.
Liquid waterproofing systems are applied by brush, roller, or spray and cure to form a seamless, flexible membrane. They are particularly useful in areas with complex geometry — around pipes, drainage collars, parapet bases, and expansion joints — where sheet membranes are difficult to apply without creating vulnerable seams.
These systems are commonly used as a complement to sheet membranes at detail areas, or as a standalone solution on terraces with extensive geometric complexity. Cure time and the number of coats required depend on the specific product and ambient conditions.
Self-adhesive membranes eliminate the need for open flame during application, making them suitable for occupied buildings or areas where fire risk is a concern. They are applied cold, with a peel-and-stick backing that bonds to the prepared substrate. Proper surface preparation — including priming — is critical to achieving reliable adhesion.
These systems are available in various formulations for both below-grade and above-grade applications. On accessible terraces, they are typically protected by a screed or paver system to prevent damage from foot traffic and UV exposure.
An effective waterproofing system depends on proper drainage. Water that cannot drain efficiently exerts hydrostatic pressure on the membrane and accelerates its deterioration. Slope correction — establishing minimum drainage gradients toward the terrace's drainage points — is a fundamental part of any membrane replacement project.
In some cases, a drainage mat or layer is installed above the membrane to facilitate water movement even when the surface above is covered with pavers or tiles. This protects the membrane from direct traffic load while allowing water to reach the drains efficiently.
A controlled flood test is the starting point for understanding what is happening beneath the surface. Contact us to discuss the condition of your terrace.