Waterproof membranes you won't find anywhere else.

Seal It Up Waterproofing was contracted to repair a 1930s leaking Penthouse terrace balcony in 2020.

the balcony was adorned with pot plants that covered roughly 30% of the space.

 Root systems had penetrated through the terrace membrane and into the segmented platform.

 whenever the plants were watered or in torrential rain downpour it rained in the apartments below.

Problematic leaks could not be isolated by patching membrane on.

We came up with an ambitious solution to rectify the true nature of the leaks!


We moved around 60 tonnes of concrete surface pavers and pot plants to get to the membrane.

roughly 52 tonnes of sandstone paver, tile glue, cement topping and failed membrane were removed and disposed of.

paths had formed through the underlying sheet membrane and sandstone paver system.

the slabs had never been waterproofed, witch is typical in buildings of this era.

the external wall and connecting floor around the balcony had various signs of cracking that equated to, 

movement created by the water damage.

 segments of concrete slab and expansion joint that formed the platform under the penthouse where revealed.

several of the segments formed under the penthouse apartment were lapped with lead flashing.

 this  allowed for pooling water to penetrate into the slab joins that where concealed and out of reach, 

directly below the penthouse apartments internal suspended timber floor boards.,

Pooling water remained undetected.

the slab surface of the balcony was repaired with our signature fibreglass reinforced sheet membrane.

New balustrade was approved to add safety to the terrace.

the engineered balustrade pedestals were sealed with chem set and reinforced with membrane.

the internal and external balcony walls were re-waterproofed.

we replaced the existing concrete pavers and pot plants.

the project was finalized within our clients budget.

the apartment directly below the penthouse experienced a leak that was identified to be coming from one of the penthouse chimneys.

we flood tested the terrace balcony and provided evidence that the source of the leak was from under the penthouse.

 A roof chimney flashing was installed by a roofing contractor at the end of our contract.

 The roof flashing was turned under instead of over right before christmas.

Torrential downpour tracked and pooled into the segmented slabs underneath the penthouse floor boards and into the ceiling of the apartment below. 

The flashings and damages where repaired by the roofing contractor.

now in 2024 the owners have gained confidence and are assured by having waterproofed the slab level, while the large array of pot plants on the terrace that are watered daily or torrential rain do not affect the rest of the building.