Rooftop Waterproofing: Why It Fails and How We Fix It Properly

Rooftop and podium membranes protect the structural slab and every space below it. Once a membrane fails, water travels through shrinkage cracks, cold joints and penetrations, so where a leak shows up inside is rarely where the water is getting in.

Ongoing water entry corrodes the reinforcement, which cracks and spalls the concrete and can reduce the slab’s structural capacity. Hitech Remedial Builders delivers remedial waterproofing to the scope documented by the Design Practitioner, with full quality controls.

Common failure mechanisms

The rooftop failures we rectify typically trace back to one or more of the following:

• Membrane Failure. UV exposure, adhesion failure, leading to cracking, embrittlement.
• Inadequate substrate preparation. Contaminants, excess moisture content or an incorrect surface profile prevent the primer and membrane from achieving full bond.
• Insufficient falls. Ponding keeps the membrane under sustained hydrostatic and UV load and concentrates deposits at low points.
• Poor detailing at terminations. Upturns, hobs, internal corners without bond breakers, penetrations and outlets without puddle flanges are the most frequent points of entry.
• Movement joints not carried through. Where structural or control joints are bridged rigidly, the membrane tears as the slab moves.
• System incompatibility or under-application. Mixed systems, missing primers and insufficient dry film thickness all shorten service life.
• Lack of protection. Pavers, ballast and plant installed without a protection or separation layer damage the membrane mechanically.

Typical defect indicators

Indicators that usually prompt an investigation include:

• Water ingress, staining or mould on soffits and ceilings of the level below
• Ponding that persists 24 to 48 hours after rainfall
• Blistering, splitting, debonding or crazing of the membrane, particularly at upturns and terminations
• Efflorescence and calcite deposits along cracks and cold joints
• Rust staining, delamination or spalling indicating reinforcement corrosion

These are assessed by a Building or Waterproofing Consultant, whose investigation and documentation define the remedial scope we deliver.

How we deliver the scope

We work to the Design Practitioner’s Regulated Design and specification. Every stage, from documentation review and pre-start planning through to remedial works and membrane installation, is carried out to the documented details, the manufacturer’s specification and current Australian Standards.

Completed works are tested by independent, NATA-accredited testing technicians before finishes are reinstated.

Quality assurance and records

Every hold point is inspected, signed off and photographed before work proceeds to the next stage. At Practical Completion the Superintendent receives a complete record of ITPs, test results, product data and warranties.

Tendering a rooftop waterproofing package?

The team at Hitech Remedial Builders has over 25 years’ experience applying waterproofing on Strata and Commercial buildings. We work alongside Engineers, Consultants and Superintendents to deliver documented scopes on programme. Send us your drawings and specification, and let’s deliver your waterproofing solution together.

Potts Point

Bankstown