Penthouse Balcony Waterproofing - Barkly Street Apartments, Footscray

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Problem

This 18-year-old penthouse apartment on Barkly Street, Footscray, features two balconies that were suffering from severe waterproofing failure. While the new owner was aware of some leaks from an inspection report, the extent of the damage proved to be far more critical than initially anticipated. The original membrane on the upper balcony had failed, causing active leaks into the living room ceiling below, evidenced by visible water stains that had developed over time.

On the lower level, damp carpet in the corner indicated water ingress through a failure point in the balcony above. As we opened up the site, we discovered a major hidden defect: half of the lower-level balcony had never had a waterproofing membrane applied during the original build. Additionally, the sliding door and window sills were also identified as active leak points.

Symptoms identified 

Damp carpet localized in the corner of the lower level
Visible watermarks staining the lower-level ceiling
Efflorescence build-up visible on the tiled surfaces
Evidence of previous “quick fix” attempts with excessive caulking

Urgency factors 

Immediate risk of further damage to internal carpets, ceilings, and other assets
Ongoing liability risk to apartments below due to balcony leaks
Structural integrity concerns regarding deteriorating timber framing and concrete
Negative impact on property value due to visible deterioration and water damage.

Solution

Approaching 20 years of age, the original waterproofing system was either failing or, in some sections, completely non-existent. A thorough visual inspection revealed critical compliance failures, such as the lack of membrane upturns at the door sills. The project also faced design flaws, including internal and external floor levels sitting at the same height, posing a risk of water ingress

Recommended solution

Our strategy involved a complete strip-out: removing tiles, screed, and failing membrane on both the upper lightweight and lower concrete balconies to expose the structural deck. We installed a comprehensive waterproofing system both below and above the screed. This dual-layer approach allowed for the necessary membrane upturn below the screed to accommodate the matching floor levels. We then re-screeded to correct the falls to drains, utilised modern waterproofing products, and sealed all pipe and balustrade penetrations.

Materials and methods

Primer: Gripset E60 epoxy primer for green concrete and Gripset GP primer
Sub-screed Membrane: Gripset BRW-PFN sheet membrane installed below the screed
Sheet membrane overlaps: Gripset 38FC and P39 used to seal sheet membrane overlaps
Top membrane: Gripset Xpress liquid membrane applied above the screed
Bond breaker: Gripset BRW PF tape and caulking
Flashings: Metal equal angle flashings installed at floor-to-wall junctions
Detailing: Comprehensive sealing around all balustrade posts, pipe penetrations, and puddle flanges (turning membrane down into the flange)
Drainage: Falls to drains corrected to no less than 1:100 to prevent water stagnation
Finishing: Epoxy grout used for tiling to provide an extra barrier
Compliance: All works installed to NCC and Australian Waterproofing Standard AS 4654.2-2012, where possible.

Implementation process

Demolition phase: We removed existing tiles and screed from both balconies. We encountered difficult-to-remove “peel and stick” membrane and confirmed the absence of membrane on half the lower balcony.
Substrate preparation: Grinded the substrate with industrial equipment to remove old membrane residue and contaminants.
Waterproofing below screed: We installed Gripset sheet membrane, detailing upturns to doors and balustrade posts with liquid membrane, and securing downturns into puddle flanges.
Metal flashings: To protect the floor-to-wall joints from water ingress after demolition, we installed metal equal angle flashings.
Screeding and top membrane: We re-screeded the balconies to rectify drainage falls. Due to a wet spring, we applied two coats of E60 epoxy vapour barrier before applying the final liquid membrane for superior protection.
Finishing work: The balcony was tiled and finished with epoxy grout for added waterproofing durability.
Caulking: All joints and junctions were professionally caulked.
Quality testing: Post-installation testing was conducted on all balconies to confirm complete coverage and waterproofing effectiveness.

Challenges Overcome

Adverse Weather: A particularly wet Melbourne spring limited the days available for effective curing. We adapted by using Gripset BRW-PFN sheet membrane and Gripset Xpress (fast cure) liquid membrane to keep the project on track.
Hidden Defects: During the works, we discovered the door sill was leaking, with previous owners having caulked over weep holes. We engaged specialists, Mr. Right, to perform a precision injection into the sill to permanently stop this leak.

Results

The penthouse apartment is now completely leak-free. Both the upper and lower balconies are fully sealed, featuring membrane upturns under the door sills to ensure a tanked, watertight finish.

Every junction, from balustrade posts to floor-to-wall substrates, is sealed, with epoxy grout providing an additional layer of protection. The new tiling offers a fresh aesthetic update, and the client is thrilled with the outcome.

Long-term benefits 

Robust protection of the building structure from future water damage
Complete elimination of water ingress into the apartment
Total resident satisfaction and peace of mind
Enhanced property value through quality restoration
Improved apartment aesthetics

Additional value delivered

As part of our commitment to customer satisfaction, we identified and arranged repair of the door sill, and internal ceiling plastering.

Service: Leak detection, balcony waterproofing, screeding, and tiling  

Application: Gripset Xpress liquid membrane, Gripset BRW-PFN sheet membrane  

Solution: Complete waterproofing of approx. 60m² penthouse area, leak detection, drainage correction, screeding, tiling, and caulking

Time to complete: Three months    

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