ROOFTOP WATERPROOF MEMBRANE REFURBISHMENT

ROOFTOP MEMBRANE RENEWAL – INSTALLATION OF NEW UV-RESISTANT ACRYLIC MEMBRANE

Singapore Waterproofing was recently contracted to perform remedial repairs to the existing rooftop waterproofing membrane of a costal multilevel apartment property in Singapore. There were several weak points in the existing membrane. Cracks, poor adhesion points and reduced thickness in the existing membrane were allowing water to seep through to the substrate. In some areas, the membrane was peeling off or was missing.

Concrete is known to be inherently weak in tensile strength. Cracks and voids can also form due to thermal expansion, contraction, concrete shrinkage and building movement and water will seep through these voids.

Roofs are constantly exposed to direct sunlight and rain, making them vulnerable to tremendous environmental stresses that can affect their physical properties and performance. Selecting the correct waterproofing system is imperative to keeping the roof water-tight so to ensure the structural integrity and to protect the homes and assets of the residents.

For a flat roof to function properly and not leak, the surface water needs to be discharged quickly without ponding or stagnation. Water ponding on a flat roof is one of the main causes of waterproofing membrane deterioration because most membranes such as acrylic membranes are not designed to withstand pooling water. That being said, long-term contact with moisture is bad for any roofing material. Dust, plant matter, pollution and other items from the environment mix in with the pooling water, turning it into a muddy consistency that attacks the membrane. When the water dries out, the crust cracks and puts the membrane under stress. Over time, this often causes the membrane to blister, crack and peel – allowing water to leak through to the substrate.

Proper design of falls is an essential consideration in the overall drainage of a flat roof. Falls create flow paths to direct the drainage of rainwater away from the roof to suitable discharge points. To be effective, it is essential to clear surface water as rapidly as possible from the flat roof to avoid ponding or stagnation of water on the roof itself.

The key to successful remedial waterproofing is thorough surface preparation and vigilant detailing of all penetrations and junctions, married up with high-quality materials.

• We opened and cleaned out weep holes and exposed flashing to improve the drainage of rainwater by directing the water to hit the flashing and escape.

• Decay and voids had formed in the joints between the bricks, allowing the entrance of water. We repointed the brick wall by renewing the pointing (the external parts of mortar joints) bringing back the physical appearance and integrity of the brickwork.

• When repointing was completed and dried, our proprietary Hi-Tech non-visible penetrative sealant was applied to impregnate the brick wall, creating a long-lasting water barrier against water penetrating the brickwork.

• The top of the brick poles, anchor points, and some cracks were joint sealed with mastic.

• Acrylic UV resistant membrane was applied on top of brick poles providing an added protection against the elements.

• On the surface-prepared rooftop, we installed a heavy-duty, UV resistant modified acrylic membrane in multiple layers on to a moisture barrier primer system.

• The primer system helps prevent bubbling or blistering, which often occurs if not included in remedial waterproofing applications.

• We applied a mastic joint sealant to floor/wall joints and wall/roof joints before installing a moisture barrier primer system, followed by a UV-resistant Acrylic membrane to the compressed fibre cement cladded walls (FC sheet cladding).