Balcony Waterproofing for a Double Storey Landed House in Seri Kembangan
Water leakage from an exposed balcony can eventually affect the rooms or spaces directly below it. At this double-storey landed house in Seri Kembangan, Selangor, the homeowner was experiencing water leakage at the car porch ceiling, with visible water stains appearing during rainy days.
ARCHTECH inspected the approximately 300 sq ft balcony above the affected car porch and found several conditions that could contribute to recurring water ingress:
- the existing liquid waterproofing membrane had deteriorated
- hairline cracks were present on the balcony slab
- water marks indicated areas where rainwater had repeatedly remained on the balcony surface
Rather than applying another layer over the deteriorated waterproofing, ARCHTECH removed the existing membrane before installing a new primer and torch-on membrane waterproofing system.
The waterproofing works also included a 300 mm membrane upturn at the perimeter to strengthen protection at the balcony to wall junctions. After installation, a water flow test was carried out to check that rainwater could drain properly toward the outlet instead of remaining on the balcony surface.
The balcony waterproofing works resolved the leakage affecting the car porch below and are backed by a 10-year warranty.
Project Overview
Project Type: Double-storey landed house
Location: Seri Kembangan, Selangor
Waterproofing Area: Balcony
Area Covered: Approximately 300 sq ft
Existing Waterproofing: Deteriorated liquid membrane
Leakage Symptom: Water stains and leakage at the car porch ceiling during rainfall
Site Conditions: Hairline slab cracks and signs of recurring water retention
New Waterproofing System: Primer + Torch-On Membrane
Perimeter Detailing: 300 mm membrane upturn
Post-Installation Check: Water flow test toward drainage outlet
Warranty: 10 years
Application By: ARCHTECH Waterproofing Specialist
What ARCHTECH Found During the Balcony Inspection
Before recommending a new waterproofing system, ARCHTECH inspected the balcony and the affected car porch area below to understand the conditions associated with the recurring leakage.
Several issues were identified.
1. Deteriorated Existing Liquid Waterproofing Membrane
The balcony had previously been waterproofed using a liquid membrane system. During inspection, the existing waterproofing layer showed signs of deterioration and was no longer providing reliable protection against rainwater penetration.
Instead of applying another waterproofing layer directly over the deteriorated membrane, ARCHTECH recommended removing the existing waterproofing before installing the new system.
2. Hairline Cracks on the Balcony Slab
Hairline cracks were also found on the balcony slab.
Although small cracks may appear minor, they can become potential pathways for water when the balcony is repeatedly exposed to rainfall, especially when the existing waterproofing layer has already deteriorated.
3. Signs of Recurring Water Retention
Water marks were visible on parts of the balcony slab after rainfall, indicating that rainwater had been remaining on the surface instead of draining away quickly.
Recurring water retention increases the amount of time the waterproofing system is exposed to standing water and can place additional stress on already deteriorated waterproofing.
4. Leakage Was Already Affecting the Car Porch Below
The waterproofing problem had progressed beyond the balcony surface.
During rainy days, water leakage and visible water stains appeared on the car porch ceiling directly below the balcony, which was the main symptom that prompted the homeowner to seek waterproofing rectification.
ARCHTECH’s Assessment
Based on the site inspection, ARCHTECH identified a combination of conditions that needed to be addressed rather than relying on another surface-level repair:
- deteriorated existing liquid waterproofing
- hairline cracks on the balcony slab
- recurring water retention after rainfall
- active leakage affecting the car porch ceiling below
Because the existing waterproofing had already deteriorated and leakage was occurring, ARCHTECH recommended removing the old waterproofing layer and installing a new waterproofing system rather than simply adding another coating over the existing surface.
Why ARCHTECH Selected a Torch-On Membrane System
After assessing the balcony condition, ARCHTECH selected a primer and torch-on membrane system for the rectification works.
The decision was based on the actual site condition rather than a preference for one particular waterproofing method.
In this project, the existing liquid waterproofing membrane had already deteriorated, hairline cracks were present on the slab, and signs of recurring water retention were visible after rainfall. Leakage had also begun affecting the car porch ceiling below.
Instead of applying another coating over the deteriorated waterproofing, the existing membrane was removed so that a new waterproofing system could be installed on a properly prepared substrate.
Why Torch-On Membrane Was Suitable for This Balcony
For this particular balcony, a torch-on membrane system provided several advantages:
- suitable for an exposed external balcony subjected to regular rainfall and sunlight
- creates a durable waterproofing layer with properly sealed membrane overlaps
- allows waterproofing continuity from the horizontal balcony surface into perimeter upturns
- provides a robust replacement system after removal of the deteriorated existing membrane
- suitable for a rectification project where active leakage was already occurring
A 300 mm membrane upturn was also incorporated along the relevant perimeter areas to strengthen waterproofing protection at the balcony-to-wall junctions.
Why ARCHTECH Does Not Recommend the Same Waterproofing Method for Every Project
The fact that the previous waterproofing system was a liquid membrane does not mean liquid membrane is unsuitable for all balconies.
Different waterproofing methods — including torch-on membrane, liquid membrane, cementitious membrane, PU coating, clear coating, TPO membrane and PU injection — are suited to different building conditions and waterproofing problems.
Before recommending a system, ARCHTECH considers factors such as:
- existing substrate and waterproofing condition
- type and location of leakage
- cracks and movement
- water drainage and ponding conditions
- weather and UV exposure
- detailing at walls, edges, outlets and penetrations
- whether the project involves new construction or rectification
For this Seri Kembangan balcony, the site conditions led ARCHTECH to recommend removal of the deteriorated existing waterproofing and replacement with a primer and torch-on membrane system.
How ARCHTECH Carried Out the Balcony Waterproofing Rectification
Because the existing waterproofing had already deteriorated and leakage was affecting the car porch below, ARCHTECH carried out a full waterproofing rectification rather than applying another layer over the existing membrane.
Step 1: Remove the Deteriorated Existing Waterproofing
The existing liquid waterproofing membrane was removed to expose the underlying balcony substrate.
Removing the deteriorated layer allowed ARCHTECH to assess and prepare the slab properly before installing the new waterproofing system.
Because the existing waterproofing had already deteriorated and leakage was affecting the car porch below, ARCHTECH carried out a full waterproofing rectification rather than applying another layer over the existing membrane.
Step 2: Prepare and Inspect the Balcony Substrate
After removal of the old waterproofing, the balcony surface was cleaned and prepared for the new system.
The exposed slab was also checked for defects, including the hairline cracks identified during the site inspection. Proper substrate preparation is important because the performance of a new waterproofing membrane depends heavily on the condition of the surface beneath it.
Step 3: Apply the Waterproofing Primer
A compatible waterproofing primer was applied to the prepared balcony substrate before installation of the torch-on membrane.
The primer helps promote proper adhesion between the substrate and the new waterproofing membrane.
Step 4: Install the Torch-On Membrane
The torch-on membrane was installed across the approximately 300 sq ft balcony using controlled heat application.
During installation, attention was given to:
- consistent bonding to the prepared substrate
- properly sealed membrane overlaps
- continuity of the waterproofing layer
- detailing around edges and transition areas
Correct installation of membrane overlaps and junctions is important because these areas can become potential water-entry points if they are not properly sealed.
Step 5: Form a 300 mm Waterproofing Upturn
The torch-on membrane was extended approximately 300 mm vertically at the relevant balcony perimeter areas.
This upturn created waterproofing continuity between the horizontal balcony surface and the adjoining wall areas, strengthening protection at the balcony-to-wall junctions where leakage can occur if detailing is inadequate.
Step 6: Check Rainwater Flow Toward the Drain
After the waterproofing installation was completed, ARCHTECH carried out a water-flow test on the balcony.
Water was introduced onto the surface to check whether it could flow toward the drainage outlet instead of remaining unnecessarily on the balcony.
This was particularly relevant because the original inspection had identified water marks indicating recurring water retention after rainfall.
Step 7: Final Inspection and Completion
The completed waterproofing system was inspected before the project was handed over.
The rectification works successfully resolved the rain-related leakage that had been affecting the car porch ceiling below.
The completed balcony waterproofing works are backed by a 10-year warranty.
Project Result: Balcony Leakage Resolved
After completion of the waterproofing rectification works, the balcony was protected with a new primer and torch-on membrane system incorporating 300 mm perimeter upturn detailing.
A water-flow test was carried out to verify that rainwater could move toward the drainage outlet instead of remaining unnecessarily on the balcony surface.
The waterproofing works resolved the rain-related leakage and water staining that had been affecting the car porch ceiling below the balcony.
The completed waterproofing works are backed by a 10-year warranty.
ARCHTECH Expert Takeaway
In this project, the homeowner sought waterproofing rectification only after visible water stains and leakage began appearing on the car porch ceiling during rainy days.
However, the balcony already showed earlier warning signs, including:
- deterioration of the existing liquid waterproofing membrane
- hairline cracks on the balcony slab
- water marks indicating recurring water retention
These conditions show why waterproofing problems are better assessed before visible leakage becomes severe.
For homeowners, warning signs such as deteriorating waterproofing, recurring ponding, cracks, damp patches, or ceiling stains should not be treated only as surface defects. They may indicate that the waterproofing system should be inspected before further water ingress affects surrounding areas.
Frequently Asked Questions About Balcony Waterproofing
1. Why is water leaking through the car porch ceiling below my balcony?
When a balcony sits directly above a car porch, rainwater can penetrate through cracks, deteriorated waterproofing, weak perimeter detailing, or other vulnerable areas in the balcony slab.
In this Seri Kembangan project, the homeowner noticed water stains and leakage on the car porch ceiling during rainy days. ARCHTECH’s inspection found a deteriorated liquid waterproofing membrane, hairline cracks on the balcony slab, and signs of recurring water retention.
2. Can deteriorated balcony waterproofing cause ceiling stains downstairs?
Yes. Once the waterproofing layer loses its effectiveness, rainwater can penetrate through the balcony build-up and eventually appear as damp patches, water stains, or leakage on the ceiling below.
Visible ceiling stains are often a symptom of a waterproofing problem above rather than the source of the problem itself.
3. Should old balcony waterproofing be removed before a new system is installed?
It depends on the condition of the existing waterproofing and substrate.
If the existing membrane is deteriorated, poorly bonded, or unsuitable as a base for the new system, removal may be necessary before installing a replacement waterproofing system.
For this project, ARCHTECH removed the deteriorated existing liquid membrane before preparing the balcony slab and installing the new torch-on membrane system.
4. Why was torch-on membrane selected for this balcony?
ARCHTECH selected a primer and torch-on membrane system after assessing the existing waterproofing condition, hairline cracks, recurring water retention, external weather exposure, and active leakage affecting the car porch below.
The system was chosen for this particular project condition. It does not mean torch-on membrane is the best solution for every balcony.
Different balcony conditions may require different waterproofing methods.
5. Is torch-on membrane suitable for balcony waterproofing?
Torch-on membrane can be suitable for exposed balconies where a durable sheet membrane system is appropriate.
However, the most suitable waterproofing method depends on factors such as the substrate condition, existing waterproofing, drainage, cracks, detailing requirements, weather exposure, and whether the work involves new construction or leakage rectification.
6. What is a 300 mm waterproofing upturn?
A waterproofing upturn extends the waterproofing membrane vertically from the horizontal balcony surface onto the adjoining wall or perimeter area.
For this project, the torch-on membrane was extended approximately 300 mm at the relevant perimeter areas to improve waterproofing continuity at balcony-to-wall junctions.
7. Can ponding water contribute to balcony waterproofing problems?
Recurring water retention can place additional stress on a waterproofing system because the membrane remains exposed to water for longer periods.
During the Seri Kembangan inspection, water marks on the balcony slab indicated that rainwater had been remaining on parts of the surface after rainfall.
After the new waterproofing system was installed, ARCHTECH carried out a water-flow test to check that water could move toward the drainage outlet.
8. What are the early warning signs of balcony waterproofing failure?
Common warning signs include:
- deteriorating or peeling waterproofing
- hairline cracks
- recurring water retention or ponding
- damp patches
- ceiling stains below the balcony
- leakage appearing during or after heavy rainfall
Early inspection can help identify the waterproofing condition before the leakage becomes more severe.
9. Should I repair the ceiling stain first or inspect the balcony above?
If the ceiling stain appears below an exposed balcony and becomes worse during rainy weather, the balcony should be inspected as a possible source of water ingress.
Repairing or repainting the ceiling alone will not solve the problem if water is still entering through the balcony above.
A proper waterproofing assessment should identify the source of the leakage before rectification works are recommended.
10. How long is the warranty for this balcony waterproofing project?
The completed ARCHTECH waterproofing works for this Seri Kembangan balcony are backed by a 10-year warranty.
Balconies are one of the most leak-prone areas in residential properties because they are constantly exposed to rain, sunlight, and surface movement. If balcony waterproofing is not done properly, water can seep through the slab, damage adjacent walls or ceilings, and lead to repeated repair issues over time.
This project highlights why correct system selection and proper workmanship are essential for balconies, especially in landed homes where exposed upper-floor areas are directly subjected to outdoor conditions.
About ARCHTECH Waterproofing Specialist
With over 10 years of expertise, ARCHTECH delivers precise, long-lasting waterproofing solutions for residential, commercial, industrial, and institutional buildings.
By combining accurate site assessment, certified professional-grade materials, and trained in-house specialists, ARCHTECH ensures durable waterproofing performance designed to stand the test of time.
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